Communications method and device7020774Abstract The present invention relates to a communication method that includes an operation of receiving a succession of pages originating from a first site of a computer network. That method further includes an operation of memory storage of information representative of the succession of pages, outside the first site and an operation of associating a certificate of integrity with the memory-stored information representative of the succession of pages. The certificate of integrity is stored in memory in association with the information representative of the succession of pages. The certificate of integrity makes it possible to detect any alteration to the memory-stored information representative of the succession of pages, subsequent to its being stored in memory. Claims The invention claimed is: Description BACKGROUND OF THE INVENTION
According to particular features of the method according to the fourth aspect of the present invention, this method includes an operation of authenticating the user. According to particular features of the method according to the fourth aspect of the present invention, this authentication operation includes an operation of recognizing an identifier of a permanent-use means of payment. According to particular features of the method according to the fourth aspect of the present invention, the single-use means-of-payment identifier is a payment-card identifier, for example with 20 figures lying between 0 and 9. According to particular features of the method according to the fourth aspect of the present invention, the operation of opening the second session precedes the operation of opening the first session. According to particular features of the method according to the fourth aspect of the present invention, the payment operation includes an operation of verifying an identifier of the second site. According to a fifth aspect, the present invention envisages a communications method characterized in that it includes: an operation of opening a first communications session between a terminal and a site of a communications network, an operation of selecting a date, an operation of storing the said date in memory and, at the said date, an operation of automatic opening of a second communications session between the said terminal and the said site. According to particular features of the method according to the fifth aspect of the present invention, this method includes an operation of interrogating a user of the said terminal and the said second session depends on at least one response given by the said user. According to a sixth aspect, the present invention envisages a method of storing communications in memory characterized in that it includes an operation of memory storage of contents of pages accessible via a communications network and an operation of re-reading the memory-stored contents including an operation of selecting re-read speed and, when a slow re-read speed is selected, a first operation of displaying memory-stored content for a first duration and, when a high re-read speed is selected, a second operation of displaying memory-stored content for a second duration less than the first duration. According to particular features of the method according to the sixth aspect of the present invention, when a slow re-read function is selected, in the course of the first display operation, a first portion of memory-stored content is displayed and, in the course of the second display operation, a second portion of memory-stored content is displayed, the second portion being different from the first portion. According to particular features of the method according to the sixth aspect of the present invention, the second portion includes at least one page address accessible on the communications network. According to particular features of the method according to the sixth aspect of the present invention, the second portion includes at least one memory-storage date. According to particular features of the method according to the sixth aspect of the present invention, the second portion includes a page header content accessible on the communications network. According to particular features of the method according to the sixth aspect of the present invention, the method includes an operation of displaying parts of accessible pages and the first portion includes an operation of re-displaying parts of pages already displayed, in the order of their first display in the course of the display operation. According to particular features of the method according to the sixth aspect of the present invention, in the course of the memory-storage operation, the user selects the pages to be stored in memory. According to particular features of the method according to the sixth aspect of the present invention, the method includes an operation of authenticating the user, before the re-reading operation. According to particular features of the method according to the sixth aspect of the present invention, the first portion includes the second portion. According to particular features of the method according to the sixth aspect of the present invention, the first re-read operation is automatic, each element of the information stored in memory and displayed not remaining displayed for more than a predetermined duration. According to particular features of the method according to the sixth aspect of the present invention, the method includes an operation of selecting keys displayed in a tool bar on the visual-display screen where the content portions are displayed. According to particular features of the method according to the sixth aspect of the present invention, the method includes an operation of stopping re-reading and, following the operation of stopping re-reading, an operation of displaying the whole of the content stored in memory relating to the page being displayed at the moment when stopping re-reading was selected. According to particular features of the method according to the sixth aspect of the present invention, the method includes an operation of selecting re-read order, in the course of which the user selects a page-scrolling order identical to the memory-storage order or a page-scrolling order which is the reverse of the memory-storage order. According to a seventh aspect, the present invention envisages a communications memory-storage method characterized in that it includes an operation of receiving pages originating from a communications network, an operation of displaying received pages, an operation of selecting a group of pages, an operation of storing in memory the content of the said pages relating to the group selected, an operation of selecting a group of pages and an operation of re-displaying memory-stored pages relating to the selected group. According to an eighth aspect, the present invention envisages a method of transmitting a page on a communications network characterized in that it includes: a first operation of requesting transmission of a first content of the said page corresponding to a first quantity of information to be transmitted and, in the event of failure of the transmission due to a predetermined transmission duration being exceeded, an operation of automatically determining a second content of the said page, the second content corresponding to a quantity of information to be transmitted less than the first quantity and an operation of requesting transmission of the said second content of the said page. According to particular features of the method according to the eighth aspect of the present invention, the second content is a part of the first content. According to particular features of the method according to the eighth aspect of the present invention, the second content corresponds to text files. According to particular features of the method according to the eighth aspect of the present invention, the first content corresponds to files representing images and/or sounds. It will be observed that the method can be implemented at any point of the communications network, and, in particular, in the computer terminal or in a computer system of a provider of access to the said network. It will be observed that the security-protection means may also be located on the communications network, at any point and, in particular, in the computer terminal or in a computer system of a provider of access to the said network. The present invention also envisages a data site, a server, a computer, characterized in that they implement the method briefly set out above. The present invention also envisages an information medium, such as a diskette, a hard disk, a compact disc or a computer memory, which holds program instructions for: opening a communications session between a computer terminal and a data site, via a communications network, automatically detecting a preparation for payment by transmission, in the course of the said session, via the said terminal, of a means-of-payment identifier, and when payment preparation is detected, automatically security-protecting the said payment outside the said data site, at least by backing up the amount of the payment outside the said data site. The present invention envisages, according to a ninth aspect, a communications method characterized in that it includes: an operation of receiving a succession of pages originating from a first site of a computer network, an operation of memory storage of information representative of the said succession of pages, outside the said first site, and an operation of associating a certificate of integrity with the memory-stored information representative of the said succession of pages, the said certificate of integrity being stored in memory in association with the information representative of the said succession of pages, the said certificate of integrity making it possible to detect any alteration to the memory-stored information representative of the said succession of pages, subsequent to its being stored in memory. According to particular features, the method according to the ninth aspect of the present invention includes a time-stamping operation attributing a date to at least one of the reception and memory-storage operations; the said date is stored in memory in association with the information representative of the said succession of pages and the certificate of integrity makes it possible to detect an alteration to the said date subsequent to its being stored in memory. According to particular features, the method according to the ninth aspect of the present invention includes an operation of determining an address of the said first site on the said network, the said address being stored in memory in association with the information representative of the said succession of pages, and the certificate of integrity makes it possible to detect an alteration to the said address subsequent to its being stored in memory. According to particular features, the method according to the ninth aspect of the present invention includes an operation of determining a display duration for each page of the said succession, the said duration being stored in memory in association with the information representative of the said succession of pages, and the certificate of integrity makes it possible to detect an alteration to the said duration subsequent to its being stored in memory. According to particular features of the method according to the ninth aspect of the present invention, for each site of a plurality of sites of the said network, the method includes an operation of determining addresses of pages of the said site, the said memory-storage operation including memory storage of the said pages, the said pages being stored in memory in association with the information representative of the said succession of pages, and the certificate of integrity makes it possible to detect an alteration to the said pages subsequent to their being stored in memory. According to particular features, the method according to the ninth aspect of the present invention includes an operation of displaying the pages received in the course of the receiving operation, and in the course of the memory-storage operation the parts of the pages received which are displayed in the course of the display operation are stored in memory. According to particular features, the method according to the ninth aspect of the present invention includes an operation of displaying the pages received in the course of the receiving operation, and, in the course of the memory-storage operation, indicators of the parts of the received pages which are displayed in the course of the display operation are stored in memory. According to particular features, the method according to the ninth aspect of the present invention includes an operation of displaying pages received in the course of the receiving operation, and, in the course of the memory-storage operation, the parts of the received pages which are not displayed in the course of the display operation are not stored in memory. According to particular features, in the method according to the ninth aspect of the present invention, the information stored in memory in the course of the memory-storage operation includes the information, in text format, of the said succession of pages. According to particular features, the method according to the ninth aspect of the present invention includes an operation of communicating with a second site of the said network and of transmitting, to the said second site, information dependent on the first site. According to particular features, the method according to the ninth aspect of the present invention includes an operation of communicating with a second site of the said network and of receiving information originating from the said second site, the information stored in memory being representative of the said information originating from the second site. According to particular features, the method according to the ninth aspect of the present invention includes an operation of communicating with a second site of the said network and of transmitting to the said second site information representative of the said pages, the memory-storage operation being carried out by the said second site. According to particular features, the method according to the ninth aspect of the present invention includes an operation of communicating with a second site of the said network, the receiving operation being carried out via the said second site. According to particular features, the method according to the ninth aspect of the present invention includes an operation of detecting information characteristic of a transaction with the said first site, and an operation of deleting the memory-stored information representative of the said succession of pages of the said first site, the said delete operation depending on the said detection. According to particular features, the method according to the ninth aspect of the present invention includes an operation of detecting information characteristic of a transaction with the said first site, the said memory-storage operation depending on the said detection. According to particular features, the method according to the ninth aspect of the present invention includes an operation of detecting information characteristic of a transaction with the said first site, by determining a preparation for communication to the first site of information corresponding to information known as "information to be protected" kept in a memory. The present invention envisages, according to a tenth aspect, a communications method characterized in that it includes: an operation of receiving a succession of pages originating from a first site of a computer network, an operation of displaying parts of pages of the said succession of pages, an operation of memory storage of information representative of the said parts of displayed pages, outside the said first site, the said information being identified in memory as displayed and an operation of memory storage of information of parts of pages not displayed, originating from the said first site, outside the said first site, the said information being identified in memory as not displayed. The tenth aspect of the invention exhibits, according to particular features, all or some of the features of the ninth aspect. The present invention envisages, according to an eleventh aspect, a communications method characterized in that it includes: an operation of receiving, via a computer terminal, a succession of pages originating from a first site of a computer network, an operation of displaying, by the computer terminal, parts of pages of the said succession, and an operation of memory storage, at a second data site independent of the said terminal, of information representative of the said parts of pages displayed. The eleventh aspect of the invention exhibits, according to particular features, all or some of the features of the ninth aspect. The present invention envisages, according to a twelfth aspect, a communications method characterized in that it includes: an operation of receiving, by a computer terminal, a succession of pages originating from a first data site, an automatic operation of receiving, by the computer terminal, originating from a second information site, contextual information depending on an identifier of the said first site, a triggering operation, and an operation of displaying the said contextual information. The present invention envisages, according to a thirteenth aspect, a communications method characterized in that it includes: an operation of receiving, via a computer terminal, a succession of pages originating from a first site, an operation of detecting an electronic signature, an operation of memory storage of information representative of at least one page of the said succession of pages, outside the said first site, depending on the said detection. According to particular features of the method according to the thirteenth aspect of the present invention, in the course of the memory-storage operation, the information stored in memory is representative of a plurality of pages of the said succession. According to particular features of the method according to the thirteenth aspect of the present invention, in the course of the memory-storage operation, the information stored in memory is representative of at least one page at which the said electronic signature is requested. According to particular features of the method according to the thirteenth aspect of the present invention, in the course of the memory-storage operation, information stored in memory is representative of each page of the said succession. According to particular features, the method according to the thirteenth aspect of the present invention includes an operation of determining a start of a contractual document and an operation of determining the end of a contractual document, and, in the course of the memory-storage operation, the information stored in memory is representative of each page accessed between the start of document and the end of document. According to particular features, the method according to the thirteenth aspect of the present invention includes an operation of associating a certificate of integrity with the memory-stored information representative of the said succession of pages, the said certificate of integrity being stored in memory in association with the information representative of at least one page of the said succession of pages, the said certificate of integrity making it possible to detect any alteration to the information stored in memory, subsequent to its being stored in memory. According to particular features, the said signature includes a certificate of integrity stored in memory in association with the information representative of at least one page of the said succession of pages, the said certificate of integrity making it possible to detect any alteration to the information stored in memory, subsequent to its being stored in memory. According to a fourteenth aspect, the present invention envisages a communications method characterized in that it includes: an operation of receiving, via a computer terminal, a succession of pages originating from a first site, an operation of detecting an electronic signature, an operation of editing a plurality of pages of the said succession, the said electronic signature depending on the said plurality of pages. According to particular features, the method according to the fourteenth aspect of the present invention includes an operation of conjoint displaying of information representative of the said plurality of pages. According to particular features, the method according to the fourteenth aspect of the present invention includes an operation of transmitting information representative of the said memory-storage operation in association with an electronic-signature transmission operation. According to a fifteenth aspect, the present invention envisages a memory-management method characterized in that it includes: an operation of determining at least one item of data called "data to be protected", at least two operations of communicating via a communications network, and, for each communications operation: an operation of determining a preparation for transmission of data to be protected in the course of the said communications operation, an operation of memory storage of data received in the course of said communications operation, and of an indicator for determination or not determination of preparation for transmission of data to be protected, an operation of determining the necessity to delete certain memory-stored data, and when it is necessary to delete memory-stored data, a delete operation in the course of which the memory-stored data is treated differently on the basis of the memory-storage date and of the value of the said indicator. According to a sixteenth aspect, the present invention envisages a memory-management method characterized in that it includes: an operation of determining at least two levels of protection for data called "data to be protected", at least two operations of communicating via a communications network, and, for each communications operation: an operation of determining the preparation for transmission of data to be protected in the course of the said communications operation, an operation of memory storage of data received in the course of said communications operation, and of an indicator of a level of protection of data to be protected, preparation for transmission of which has been determined, an operation of determining the necessity to delete certain memory-stored data, and when it is necessary to delete memory-stored data, a delete operation in the course of which the memory-stored data is treated differently on the basis of the memory-storage date and of the value of the said indicator. According to particular features of the method according to the sixteenth aspect of the present invention, the necessity-determining operation includes an operation of comparing a memory space with a predetermined memory-space value. According to a seventeenth aspect, the present invention envisages a memory-management method characterized in that it includes: an operation of determining at least one item of data called "data to be protected", at least two operations of communicating via a communications network, and, for each communications operation: an operation of determining the preparation for transmission of data to be protected in the course of the said communications operation, an operation of memory storage of data received in the course of said communications operation, the said memory-storage operation depending on the said determination or non-determination of preparation for transmission of data to be protected. According to particular features of the method according to the seventeenth aspect of the present invention, the memory-storage operation includes an operation of encrypting memory-stored data. According to an eighteenth aspect, the present invention envisages a memory-management method characterized in that it includes: an operation of determining at least one item of data called "data to be protected", at least two operations of communicating via a communications network, and, for each communications operation: an operation of determining a transmission of data to be protected in the course of the said communications operation, an operation of memory storage of data representative of data received in the course of said communications operation, the said memory-storage operation depending on the said determination or non-determination of transmission of data to be protected, and an operation of transmitting, to the said network, information representative of the said memory-storage operation. According to particular features of the method according to the eighteenth aspect of the present invention, the said operation of transmitting information representative of the said operation is carried out by electronic mail. According to a nineteenth aspect, the present invention envisages a memory-management method characterized in that it includes: an operation of determining at least two levels of protection of data known as "data to be protected", at least two operations of communicating, via a communications network, and, for each communications operation:
According to particular features of the method according to the nineteenth aspect of the present invention, the memory-storage operation employs different data formats, in connection with the result of the said determination operation. A twentieth aspect of the present invention envisages a data-protection method characterized in that it includes: an operation of selecting software context for protection of data called "data to be protected", in the course of which a user determines in which case, among at least two of the following cases, data to be protected have to be protected; outside communications on an international communications network, for electronic-mail communications on an international communications network, and/or for Internet web site visits; an operation of detection of use, by a user, of data to be protected, in one of the selected software contexts; and an operation of memory storage of information representative of the said use. A twenty-first aspect of the present invention envisages a data-storage method characterized in that it includes: an operation of communicating, via a communications network, in the course of which data is exchanged between a terminal and the said network, an operation of memory storage of data originating from the said communications network in the course of the said communications operation, in the course of the said memory-storage operation, an operation of determining the necessity to keep the said memory-stored data, on the basis of the data sent on the said network by the said terminal in the course of the said communications operation, and an operation of keeping the said memory-stored data depending on the result of the said operation for determining the necessity to keep the said memory-stored data. A twenty-second aspect of the present invention envisages a method for contextual information characterized in that it includes: a first communications operation, via a communications network, in the course of which first data is exchanged between a terminal and a first remote server, a second communications operation, via the said communications network, in the course of which second data depending on the first remote server is exchanged with a second remote server, in the course of the said communications operation, an operation of determining the necessity to display the said second data, on the basis of the first data sent by the terminal in the course of the said first communications operation, and an operation of displaying the said second data depending on the result of the said operation for determining the necessity to display the said second data. According to particular features of the method according to the twenty-second aspect of the present invention, the said second data is representative of pages supplied by the said first remote server. According to particular features, the method according to the twenty-second aspect of the present invention includes an operation of memory storage of all or part of the said first data and of all or part of the said second data. A twenty-third aspect of the present invention envisages a method of keeping data remotely characterized in that it includes: a first communications operation, via a communications network, in the course of which first data is exchanged between a terminal and a first remote server, a second communications operation, via the said communications network, in the course of which second data depending on the first data is received by a second remote server, in the course of the said first communications operation, an operation of determining the necessity to keep the said second data, on the basis of the first data sent by the terminal in the course of the said first communications operation, and an operation of keeping the said second data depending on the result of the said operation for determining the necessity to keep the said second data. According to particular features of the method according to the twenty-third aspect of the present invention, the said second data is page addresses supplied by the said first server and, in the course of the keeping operation, at least one type of data, for example the text data, situated at the said addresses is kept. According to particular features of the method according to the twenty-third aspect of the present invention, the said second data includes an identifier of the first remote server, of the terminal, of the date of the first communications operation. According to particular features of the method according to the twenty-third aspect of the present invention, the said second data is representative of the first data which is displayed on the said terminal. A twenty-fourth aspect of the present invention envisages a method of keeping data remotely characterized in that it includes: a first communications operation, via a communications network, in the course of which first data is exchanged between a terminal and a first remote server, a second communications operation, via the said communications network, in the course of which second data depending on the first data is received by a second remote server, in the course of the said first memory-storage operation, an operation of determining the necessity to keep the said first and second data, on the basis of the first data sent by the terminal in the course of the said first communications operation, and an operation of keeping the said first data by the said terminal and the said second data by the said second server, depending on the result of the said operation for determining the necessity to keep the said first and second data According to particular features of the method according to the twenty-fourth aspect of the present invention, the said first data and the said second data are not kept in the same formats. According to a twenty-fifth aspect, the present invention envisages a method of recording data exchanged between a terminal and a remote site, characterized in that it includes the displaying of a witness on the said terminal, the said witness varying between at least two visible states when a recording is in progress and at least one of the two visible states not being displayed when the recording is not in progress. According to a twenty-sixth aspect, the present invention envisages a method of keeping data relating to a communication on a communications network, characterized in that it includes: an operation of placing the said data in memory, associated with a date when it was placed in memory, an operation of determining the necessity to compress the said data, depending on the date when it was placed in memory, and when the said determination operation indicates that it is necessary to compress the said data, an operation of compressing the said data and of memory storage of secondary data representative of the said primary data. According to particular features of the method according to the twenty-sixth aspect of the present invention, the said compression operation includes an operation of optical character recognition. According to particular features of the method according to the twenty-sixth aspect of the present invention, the said compression operation includes the selection of data formats and the elimination of data which does not have a selected format. According to particular features, the said compression operation includes the selection of at most two images per page of data received from an Internet web site. According to a twenty-seventh aspect, the present invention envisages a communications method characterized in that it includes an operation of communicating information between at least two persons and an operation of adding information to the said communications, on the basis of at least one of the following criteria: the identity of one of the said persons, and/or the content of the said information communicated. According to particular features of the method according to the twenty-seventh aspect of the present invention, the said added information includes a limitation of the legal scope of the said communication. BRIEF DESCRIPTION OF THE DRAWINGS Other advantages, aims and features of the present invention will emerge from the description which will follow, given for explanatory and not in any way limiting purposes, with regard to the attached drawings in which: FIG. 1 represents an embodiment of a device suitable for implementing the method envisaged by the present invention, FIG. 2 represents a flowchart of a first implementation of the first aspect of the method envisaged by the present invention, FIG. 3 represents a flowchart of a second implementation of the first aspect of the method envisaged by the present invention, FIG. 4 represents a flowchart of an implementation of the second and eighth aspect of the method envisaged by the present invention, FIGS. 5A and 5B represent a flowchart of an implementation of the sixth aspect of the method envisaged by the present invention, FIG. 6 represents a visual-display screen in the course of a re-reading operation of the flowchart illustrated in FIG. 5, FIG. 7 represents a flowchart of an implementation of the third aspect of the method envisaged by the present invention, FIG. 8 represents functions implemented in various computer systems linked to a communications network in the course of a first example of a succession of operations implemented in accordance with the fourth aspect of the method envisaged by the present invention, FIG. 9 represents functions implemented in various computer systems linked to a communications network in the course of a second example of a succession of operations implemented in accordance with the fourth aspect of the method envisaged by the present invention, FIG. 10 represents a visual-display screen in the course of the implementation of another embodiment of the method which is the subject of the present invention, FIG. 11 represents a flowchart of the operation of the device illustrated in FIG. 1, according to the embodiment of the method which is the subject of the present invention illustrated in FIG. 10, FIG. 12 represents a flowchart of the operation of the device illustrated in FIG. 1, according to another embodiment of the method which is the subject of the present invention, FIG. 13 represents a visual-display screen in the course of a re-reading operation of the flowchart illustrated in FIG. 12, FIG. 14 represents a flowchart of the operation of each of the embodiments illustrated in FIGS. 11 and 12, FIG. 15 represents a flowchart of the operation of a particular aspect of the present invention, FIG. 16 represents a flowchart of the operation of the device illustrated in FIG. 1, in an implementation of the fifth aspect of the present invention, FIG. 17 represents functions implemented in various computer systems linked to a communications network in the course of a third example of a succession of operations implemented in accordance with the fourth aspect of the method envisaged by the present invention, FIG. 18 represents another embodiment of the present invention, in connection with the device embodiment illustrated in FIG. 1, FIG. 19 represents another embodiment of the present invention, suitable, in particular, for the case of mobile terminals, and FIG. 20 represents another embodiment of the present invention, in connection with the implementation of an electronic signature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS For certain aspects of the present invention, the method is preferably implemented as a background task in order not to disturb the operation to which the user is accustomed, until a trigger event occurs, either deliberately on the part of the user, or by detection of confidential information to be protected. For each of the aspects of the present invention, at least one part of a software suite which implements it preferably resides in the user's terminal or in a server of a provider of access to the network in question. Each of the aspects of the present invention participates in the definition of a method and of a device for assistance to a user of a communications network. In the remainder of the description, the term "assistance software" makes reference to a particular example of implementation of certain aspects of the method and of the device envisaged by the present invention. In FIG. 1 are represented a computer terminal 100 connected, via a network 120, a server of an access provider 130 and a network 140, to a remote data site 150. In the first embodiment illustrated in FIG. 1, the terminal 100 includes, linked together by an address and data bus 109, an interface for communication on a network 101, a non-volatile backup unit 102, a pointing device 103, a visual-display screen 104, a keyboard 105, a central processing unit 106, a non-volatile central memory 107 and a random-access memory 108. The network 120 is, for example, the switched telephone network. The server of the access provider 130 is, for example, the server of the provider of access to the Internet network known by the name of AOL (trademark) or WANADOO (trademark). The network 140 is, for example, the data communications network known by the name of Internet. The remote data site 150 is implemented by a data server or a computer programmed for this purpose according to known techniques. In the first embodiment illustrated in FIG. 1, the terminal 100 is a personal computer known by the name of PC (acronym for Personal Computer), or a network computer, known by the name of NC (acronym for Network Computer). The interface for communication on a network 101 is, in the first embodiment described and represented, a modulator/demodulator or MODEM. The non-volatile backup unit 102 is, for example, in the first embodiment described and represented, a hard disk or a compact disc reader/recorder. The pointing device 103 is, in the first embodiment described and represented, a computer mouse. The visual-display screen 104 is of known type, for example with a cathode-ray tube, and is compatible with the standard known to the person skilled in the art under the name of SVGA. The keyboard 105 includes at least some keys which, alone or in combination, make it possible to select alphanumeric characters. The central processing unit 106 is, in the first embodiment described and represented, a processor, for example of the Intel Pentium trademark. The non-volatile central memory 107 holds the program instructions for the processor 106 which allows it to start up when it starts to be supplied with electricity. The random-access memory 108 is, in the first embodiment described and represented, a cache memory suitable for holding information representative of at least one page received from a site such as the remote data site 150. For implementing certain aspects of the present invention, the terminal 100 is linked, via the network 140, to a third-party site for assistance or protection 170 and/or to a third-party confidence site 180. The third-party protection site 170 and/or the third-party confidence site 180 each possess a server which keeps Internet pages. In a variant, at least one of these sites 170 and 180 is coincident with that of the access provider 130. In a general way, according to the first aspect of the present invention, when the user puts a computer system into operation, the assistance software which implements certain of the aspects of the present invention is initialized and runs as a background task. Next, as long as the user is using this computer system, the assistance software monitors the supply of information to be protected. This information is defined by its form (see, for example, the flowchart illustrated in FIG. 2) or by its particular value (see, for example, the flowchart illustrated in FIG. 3). When information to be protected is detected in the background task, an operation for protecting this information is carried out. FIG. 2 represents a flowchart of a first implementation of the first aspect of the method envisaged by the present invention. Following an operation 200 for starting up the terminal 100, in the course of an operation 201, the assistance software is automatically started. In the course of the use of the terminal 100, and in a known way, the user makes selections by using the mouse 103 or selects symbols using the keyboard 105. In the course of a test 202, the central processing unit 106 determines whether or not an icon specific to the implementation of the first aspect of the method envisaged by the present invention has been selected by the user. This specific icon may be an icon, such as the icon 1070 illustrated in FIG. 10 and represented on the visual-display screen 104, or an icon which represents a memory of personal information, known by the expression of "wallet", in the software (or "browser") for navigation on the Internet. When the result of the test 202 is negative, in the course of an operation 203, the central processing unit 106 determines whether a symbol has been selected by the keyboard 105. When the result of the test 203 is negative, the test 202 is reiterated. When the result of the test 203 is positive, in the course of an operation 204, the symbol selected is placed in memory into a "first in first out" register (known to the person skilled in the art by the acronym FIFO), which possesses dimensions at least equal to the largest of the sequences of symbols distribution of which is protected. In the course of an operation 205, characteristics for recognition of the sequence input are determined. These recognition characteristics are information which characterizes the sequence kept in the first in-first out register and which is intended to be compelled with characteristics for recognition of protected sequences. For example, recognition takes place by comparison of the content of the FIFO memory with sequences of symbols to be protected or segments of these sequences, and the characteristics are then the sequence itself or one or more of its segments. According to another example, if the information protected is a social-security number or a payment-card number, characteristics may consist of the number of figures input consecutively and of the likelihood that certain of these figures represent a month, a year, an indication of sex, information which is redundant with respect to the other figures or any other function, possibly a one-way function, which provides at least one characteristic. For example, a credit-card number possesses 16 figures, which have a relationship to one another, and an expiry date in the form of two figures for the month and two figures for the year, it being impossible for the year to be more than a few years after the date of issue of the credit-card. This supplies several characteristics of a credit-card number, without it being necessary to identify this number. For example, a French social-security number possesses the following characteristics (except for very rare exceptions): it includes 13 figures the first figure is equal either to 1, or to 2, the fourth figure is either 0 or 1, the fifth is 1 or 2 when the fourth figure is 1. In the course of a test 206, the central processing unit 106 determines whether the characteristics determined in the course of operation 205 correspond to characteristics of information to be protected. When the result of the test 206 is negative, test 202 is reiterated. When the result of the test 202 or the result of the test 206 is positive, in the course of an operation 207, the information to be protected, at least one characteristic of which has been recognized, is protected. To that end, in the course of operation 207, the user is interrogated on the data acquisition in progress by the display of a message in the window represented on the visual-display screen 104, "Are you inputting XXX", where XXX is replaced by a protected information name, for example "payment-card number, social-security number, confidential code, etc., and the user has to choose and select either "yes" or "no". Then, when the user has chosen "no", the operation 207 is completed and, when the user has chosen "yes", at least one of the protection operations set out in the implementation of the other aspects of the present invention is implemented (deleting of symbols from the information to be protected, for example by simulation of inputting the delete key "back space", placing in memory the succession of operations carried out since the operation 201, making contact with a third-party protection site 170, authentication of the user as a person authorized to divulge the information to be protected, time stamping, display of legal information, for example). Following the operation 207, test 202 is reiterated and the operations 202 to 206 proceed as background tasks until the terminal is shut down in a known way. FIG. 3 represents a flowchart of a second implementation of the first aspect of the method envisaged by the present invention. This second embodiment includes the same operations as the first embodiment, with the exception of operation 201 which is replaced by operations 301 to 304 and the operation 205 which is replaced by an operation 305. In the course of operation 301, the assistance software is automatically put into operation and causes the display, on the visual-display screen 104, in a dialogue window, of a question for inputting new information to be protected (for example "do you want to input new confidential information to be protected?") and displaying three possible responses which the user can select via the mouse 103, "yes", "no", "do not start monitoring". When "do not start monitoring" is implemented, an authentication operation 302 is carried out. If the user is authenticated, the operation of the assistance software is stopped. If the user is not authenticated, operation 301 is reiterated. When "no" is selected, test 202 is carried out. When "yes" is selected, in the course of an operation 303, the user is invited to input an identifier of the information to be protected (for example by selecting "wallet", "payment card", "social security number", "name", "driving license number", "identity card number", "date of birth", "address", "Internet access code", "bank account access code", "other", etc.), then, a part of the information to be protected, for example the first eight figures of the payment cards to be protected, the first six figures of his social-security number, the day and the month of his birth, the first letters of the street where he lives, the first figures of his postcode, etc. Then, in the course of an operation 304, characteristics for recognizing the information to be protected are determined in the same way as in the course of operation 305, and these characteristics are placed into non-volatile memory 102. Following operation 304, operation 301 is reiterated. It will be observed that these characteristics may consist of the whole of the information to be protected, in particular when the information to be protected is selected as "other". The characteristics may also consist of a predetermined number of first figures of the protected number or of any other function, possibly one-way, which supplies at least one characteristic. The reader may draw on the methods for producing redundancy for transmission-error correction (known by the acronym FEC, standing for Forward Error Correction), for example the verification sums known by the name of "checksum". In the case of the information kept in the "wallet" register, the user supplies the name of the browser which he is using, or runs it and selects "wallet", in such a way that the memory address to be protected or the means of accessing it are determined automatically by the assistance software. In the course of operation 305, characteristics for recognizing the sequence of symbols in memory are determined in the same way as in the course of operation 304. It will be observed here that only two data-input means are employed in FIGS. 2 and 3. However, other data-input means, such as a microphone associated with speech-recognition software, a scanner associated with optical character recognition software, or a camera, can be employed in accordance with the first aspect of the present invention. It will also be observed that the information to be protected may take forms other than a sequence of symbols, such as an image of the back of the eye, a voice signature, a signature input by using the mouse, a printout read by an optical or thermal sensor, etc. In a variant, not represented, operations 201 to 207 are implemented automatically only when communication is implemented. Hence, when children access a data site, for example via the Internet, confidential information is protected. In general, according to the second aspect of the present invention, contents of data files received on a communications network are placed in memory and this memory space is managed in such a way as to warn that it is saturating the total memory space available for the other applications. Memory storage and deleting of the content received on the network is organized hierarchically. In general, according to the eighth aspect of the present invention, when the transmission of a set of information fails because of a limitation in the available pass band or of the maximum transmission duration authorized for a set, a request for transmission of a subset of the said set strictly including less information than the set, is automatically sent. The set preferably corresponds to several files and the subset includes one or more of the said files. FIG. 4 represents a flowchart for implementation of the second aspect of the method envisaged by the present invention, in which a memory space is managed. In the course of an operation 400, the user causes a communications session to be opened between the terminal 100 and the access provider 130, via the network 120, in a known way. In the course of an operation 401, the assistance software causes the display of a selection window and of a menu including one or more subjects which the user has already chosen and/or an option of defining a new subject. The user chooses one of the subjects displayed and/or identifies a new subject. For example, these subjects may be "stock market", "sport", "motor cars", "audio-visual equipment", "others" etc. As soon as the user has selected a subject, the selection window is deleted from the visual display screen 104. Then, in the course of an operation 402, the user, in a known way or starting from one of the pages already related to the subject which he has selected (to this end, when the user has chosen a subject, he may select and see displayed a list of the last pages visited in connection with the chosen subject, in the same way as the browser software offers a list of sites known as "favorites". The user can then click on a displayed address), selects an Internet page which he wishes to view and a request is transmitted, via the access provider 130, to a site which holds the information relating to the selected page. The site in question transmits this information to the terminal 100, via the network 120. In general, transmission is carried out with a pass band limited as a function of the traffic present on the network. It then happens that the access provider stops the transmission when the predetermined duration is exceeded. For example, when, at the end of a period of 20 seconds, the information relating to the structure of the page has not been transmitted, the access provider transmits a transmission-failure message. In the course of the test 403, the central processing unit 106 determines whether such a message has been received. When the result of the test 403 is positive, that is to say in the case of a failure to transmit the page, in the course of an operation 404, the transmission of a part of the content of the page is de-activated, the request for transmission of the page is re-transmitted and the test 403 is reiterated. For example, if, for the same page, several transmission failures occur in succession, the following contents are successively de-activated: animated image files (for example MPEG files), static image files (for example JPEG files), sound files (for example WAVE files), graphics files. According to another example, with the content of the page being described to the MPEG-7 format, the de-activated files are graded as a function of their content. According to a third example, at each iteration of operation 404, the de-activated files include the file of largest dimensions, with the exception of the file which gives the structure of the page and/or of the text file. When the result of the test 403 is negative, in the course of operation 405, at least a part of the content of the selected page is received and the de-activations carried out in the course of operation 404 are cancelled for the next page to be received. In the course of the test 406, the central processing unit 106 determines whether the page received is different from all the pages held in memory of the terminal 100. To that end, the central processing unit 106 compares the address of the page as well as the dimensions of each file at this page with the address of all the pages held in memory and the dimensions of the memory-stored files which are relative to the said address, if it is recognized. When the page is not recognized as being stored in memory, the result of the test 407 is positive and, in the course of an operation 407, the central processing unit 106 causes memory storage of all the files associated with the received page, relating to the address of the page, on the hard disk 102. When the result of the test 406 is negative, that is to say if the page received is recognized as already being stored in memory, or as a result of operation 407, in the course of an operation 408, the central processing unit 106 stores in memory, relating to the said memory-stored page, the date, the subject selected in the course of operation 401, as well as a link with the page previously selected in the course of the same communications session with the site which holds the information relating to the selected page, if the operation 408 is not being carried out for the first time in the course of this session. In the course of an operation 409, at least a part of the received page is displayed, according to known techniques, and the user can shift this page, put an end to the communications session, and more generally use all the functions of his browser software. In the course of a test 410, the central processing unit 106 determines whether or not another page is being selected by the user. When the result of the test 410 is positive, a transmission request is sent to the site which holds the information relating to the new page selected, with validation of the transmission of all the files attached to the said page, and test 403 is carried out. When the result of the test 410 is negative, in the course of a test 411, the central processing unit 106 determines whether or not the memory allocated by the user for holding the content of pages received via the communications network 120 has been exceeded. It will be observed here that, in the course of the installation of the assistance software, the user allocates a memory space on the hard disk 102 for memory storage of page contents. When the result of the test 411 is negative, operation 409 is reiterated. When the result of the test 411 is positive, in the course of operation 412, the oldest files kept in the memory space allocated to holding the pages received are sorted on the basis of predetermined criteria and certain files which do not meet the said criteria are deleted. By way of example, the user can attribute to certain pages an automatic deletion prohibition (see, for example, operation 519, in FIG. 5B), and the files which are endowed with this prohibition are not automatically deleted. In the event that all the files stored in memory are endowed with this prohibition, the user is warned that he has to: either allocate supplementary memory space to the function of memory storage of pages received via the communications network 120 (he can then carry out operation 412 again), or choose to delete files relating to memory-stored pages (he is then invited to carry out manual deletion) (see, for example, operation 517, FIG. 5B), or authorize compression of the said files with a compression ratio greater than that which is used for the memory-stored files (in this latter case, in the course of operation 412, the image files and/or the sound files, of the first pages stored in memory are decompressed then recompressed with a higher compression ratio, until the allotted memory space is complied with). By way of a second example, not exclusive of the first example, the files are deleted on the basis of the type, the animated image files, fixed image files, then sound, then graphics, then text files being deleted after different periods. For example, the animated image files are kept for half as long as the fixed image files which are kept for half as long as the sound files, which are kept for half as long as the graphics files which are kept for half as long as the text files which are kept for half as long as the links between the pages which are kept for half as long as the page addresses. By way of a third example, not exclusive of the first two, the information relating to the pages stored in memory for the longest time is deleted first. By way of a fourth example, not exclusive of the first three, the information relating to the various subjects is kept for different durations. By way of a fifth example, not exclusive of the first four, the information relating to the pages of a site where a transaction has been carried out is kept longer than the others, and, for example, for least a period equal to a legal guarantee plus a maximum delivery period (for example, if the guarantee period is 12 months, the information will be kept for a duration of at least 15 months). Following operation 412, operation 409 is reiterated. FIGS. 5A and 5B represent a flowchart for implementation of the sixth aspect of the present invention. Following the assistance software being put into operation, either automatically upon the terminal 100 being put into operation, or by selection of a specific icon (not represented) in the course of operation 500, in the course of operation 501 the user can select a function of rereading of pages received in the course of communications on a communications network and stored in memory on the hard disk 102. In the course of an operation 502, the user selects a function related to the re-reading, for example by using icons illustrated in FIG. 6. In the course of the test 503, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of arranging the pages stored in memory by subject. When the result of the test 503 is positive, in the course of an operation 504, the central processing unit 106 displays a list of the existing subjects and, when the user has chosen a subject, organizes the information held in memory in connection with the subject selected, date by date, in reverse chronological order. Following operation 504, operation 502 is reiterated. When test 503 is negative, in the course of a test 505, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of sequencing the pages stored in memory by date. When the result of the test 505 is positive, in the course of an operation 506, the central processing unit 106 organizes the information kept in memory, data by date, in inverse chronological order. Following operation 506, operation 502 is reiterated. When the test 505 is negative, in the course of a test 507, the central processing unit 106 whether or not the function selected in the course of operation 502 is that of carrying out rapid re-reading of the pages stored in memory. When the result of the test 507 is positive, in the course of an operation 508, the central processing unit 106 displays first page portions, and each page during a first predetermined period, in the order defined by the sequencing, or, by default, date by date, in chronological order. The first page portions preferably include at least the address of the page and, preferably, the top part of the page including at least the texts of this upper part of the page. When the operation 506 is launched, operation 502 can be reiterated. When test 507 is negative, in the course of a test 509, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of carrying out slow re-reading of the pages stored in memory. When the result of the test 509 is positive, in the course of an operation 510, the central processing unit 106 displays second page portions, and each page for a second predetermined duration longer than the first predetermined duration, in the order defined by the sequencing, or, by default, the files endowed with automatic delete prohibition (see operation 519) before the others and, in each group, date by date, in chronological order. The second page portions preferably include at least the first portions. The second portions may include the texts from the whole page, with the page scrolling, from top to bottom, in order to display these texts. They may also include the graphics, the static images, the sounds and the animated images. When operation 510 is launched, operation 502 can be reiterated. When the test 509 is negative, in the course of a test 511, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of stopping re-reading. When the result of test 511 is positive, in the course of an operation 512, the central processing unit 106 stops the scrolling on the current page and causes display and distribution of the content of each file associated with the said page, including the sound and animated-image files. Following operation 512, operation 502 is reiterated. When test 511 is negative, in the course of a test 513, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of carrying out slow re-reading in the reverse direction. When the result of test 513 is positive, the same operations as in the course of operation 510 are carried out, but in reverse order. When the operation 514 is launched, operation 502 can be reiterated. When the test 513 is negative, in the course of a test 515, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of carrying out rapid re-reading in the reverse direction. When the result of the test 515 is positive, the same operations as in the course of operation 508 are carried out but in the reverse direction. When operation 516 is launched, operation 502 can be reiterated. When test 515 is negative, in the course of a test 517, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of deleting information. When the result of the test 517 is positive, the page being displayed remains displayed throughout the operation 518. A list of the files attached to the page being displayed is displayed in a window superimposed on the page being displayed and the user selects the files which he wishes to delete. These files are then deleted from the hard disk 102. When the delete operation is carried out, the function previously selected before that of deletion is repeated and operation 502 can be reiterated. When test 517 is negative, in the course of a test 519, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of giving the page being displayed automatic delete prohibition. When the result of the test 519 is positive, in the course of an operation 520, the address of the page being displayed is associated with a flag which indicates that the files relating to this page cannot be deleted automatically, for example in the course of an automatic memory-management operation. When operation 520 is carried out, operation 502 can be reiterated. When test 519 is negative, in the course of a test 521, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of changing the reference subject of the page being displayed. When the result of the test 521 is positive, in the course of an operation 522, the page being displayed remains displayed throughout the duration of operation 522 and, in a window superimposed on the page being displayed, the various subjects referenced as well as an option of creating a new subject are offered to the user. The user then selects the new subject to which the page being displayed has to be related and the subject associated with the page is altered in memory on the hard disk 102. When operation 522 is carried out, operation 502 can be reiterated. When the test 521 is negative, in the course of a test 523, the central processing unit 106 determines whether or not the function selected in the course of operation 502 is that of exiting from the re-read function. When the result of the test 523 is positive, the re-read function is stopped and the dialogue window displayed on the visual-display screen 104 allows the user to select other functions. When the result of the test 523 is negative, the operation being carried out, if it is one of operations 508, 510, 514 or 516, and operation 502 can be reiterated. FIG. 6 represents a visual display screen 600 in the course of a re-reading operation of the flowchart illustrated in FIG. 5. This screen 600 corresponds, for example, to what is displayed by the visual-display screen 104 in the course of one of operations 508, 510, 514 and 516, when operation 502 can be reiterated. On the screen 600, a main area 620 represents a part of a page re-read from memory on the hard disk 102. A graphics area 610 represents pages held in memory on the hard disk 102 and their links. Here the pages received on the date Nov. 6, 1999, in the course of a communications session opened at 11 hours and 5 minutes are represented in the upper part of the graphics area 610, and the first pages received on Nov. 6, 1999, in the course of a communications session opened at 17 hours and ten minutes, are represented in the bottom part of the graphics area 610. Each page is represented in the graphics area 610 in the form of a circle, and two circles which touch and the centers of which are linked by a solid straight line correspond to two pages which have been visited successively. For example, a succession of circles 1 to 5 represented as follows ##EQU1## where the circles 1 and 2, 2 and 3, 3 and 4 and 3 and 5 are touching respectively in pairs, and the centers of which are linked by a solid straight line, two by two, indicate that the user has visited pages 1, 2, 3, 4, 3 and 5 successively. If a link is indicated by a straight line between two circles which are not touching, that indicates that the two pages represented possess identical addresses. The black circle indicates the page being displayed. The links drawn out in broken lines relate to the pages which are represented in two different communications sessions, that is to say which were received in the course of two different sessions. When one of these straight lines (solid or broken) includes an arrow, that indicates that the page was received with more information in the course of the occurrence indicated by the point of the arrow than in the course of each other occurrence. The bottom function selection area 630 includes geometric shapes, some of which are well known to users of a video recorder or a tape recorder, and written information. The leftmost rectangle, referenced 641, indicates the subject being re-read, here "photo apparatus". The rectangles 642 and 643 indicate that there are two other subjects which the user may choose. The double triangle turned to left 631 corresponds to the rapid re-reading in reverse direction of the selected sequencing and makes it possible to select operation 516. The triangle turned to left 632 corresponds to the slow re-reading in the reverse direction of the selected sequencing and makes it possible to select operation 514. The square 633 corresponds to the stopping of re-reading and makes it possible to select operation 512. The triangle turned to right 634 corresponds to the slow re-reading in the selected sequencing order and makes it possible to select the operation 510. The double triangle turned to right 635 corresponds to rapid re-reading in the order of the selected sequencing and makes it possible to select operation 508. The word "effac" allows the user to start operation 518. The word "impor" 637 allows the user to start operation 520. The word "out" 638 allows the user to exit from the re-reading function. The word "chang" 639 allows the user to select operation 522. It will be observed that the user can select the next page to be displayed directly from the diagram displayed in area 610, by using the mouse 103. In general, according to the third aspect of the present invention, in the course of a communications session between the terminal 100 and a site 150, a second communications session is opened between the terminal 100 and a protection site 170 and information relating to the site 150 is transmitted automatically to the protection site 170. Information relating to the first communications session is preferably transmitted back automatically to the terminal 100 by the protection site 170. FIG. 7 represents a flowchart for implementing the third aspect of the method envisaged by the present invention. In the course of an operation 702, the site 150 and, in the course of an operation 704, the terminal 100 open a communications session between them. In the course of an operation 706, the site 150 and, in the course of an operation 708, the terminal 100 initiate communication of protected information, and, in the case illustrated in FIG. 7, a transaction necessitating on-line payment by transmitting an identifier of a means of payment. In the course of an operation 710, the terminal 100 and, in the course of an operation 712, the assistance or protection third party 170 open a second communications session. In the course of an operation 714, the terminal 100 transmits, to the protection site 170, an identifier of the site 150, for example in the form of an identifier of the page being displayed, and, more particularly, the address of the said page. In the course of an operation 716, the protection site receives the said identifier. In the course of an operation 718 the protection third party transmits to the terminal 100 information relating to the first session. For example: the country where the site 150 is based, the law applicable to the communication of the protected information, identified by the country of residence of the site 150, the period of legal guarantee of a purchase from the site 150, the degree of risk of a fraudulent transaction with the site 150, evaluated on the basis of statistics available, for example, from a site such as "fraud.org". a degree of satisfaction of other customers of the site 150, evaluated on the basis of information transmitted by the customers or by a site such as "bizrate.com", a level of punctuality of deliveries made, evaluated on the basis of information transmitted by the previous clients or by other "rating" sites, advertising relating to the products promoted by the site 150, an offer to make contact with sites competing with the site 150, an offer of automatic detection of encryption of the first session, the date of establishment of the site 150, obtained from the site "internic.com", an offer of advice relating to the transaction in progress, a certification of information originating from the site 150, a certification of the site 150, for example is performed by the site "verisign.com", possibly supplemented by operations recommended by that site, a certified date of the first session intended to be combined with information to be stored in memory, a substitute means-of-payment identifier in order to protect the user's usual means of payment, are information relating to the first session. The information relating to the first session which is transmitted by the protection site 170 preferably includes information relating to the site 150 and/or to the technical characteristics of the first session. However, in complement, information such as: an offer to make contact with a search engine for best prices, a questionnaire to be filled in, the responses to which are intended to be kept in memory, advice as to general prudence, for example drawing on that offered by the site "fraud.org", may be transmitted by the protection third party 170. The terminal 100 receives and processes this information in the course of operation 720. In FIG. 7 the case has been represented in which the user chooses to visit another site, called "third party merchant", a competitor of the site 150, for example on the basis of the result of a search carried out by a best-price search engine. In the course of operation 722, the terminal 100 and, in the course of operation 724, the third-party merchant site open a third communications session. In the course of operation 726, the terminal 100 and, in the course of operation 728, the third-party merchant site initiate communication of protected information and, in the case illustrated in FIG. 7, a transaction requiring on-line payment by transmission of a means-of-payment identifier. In the course of an operation 730, the terminal 100 and, in the course of an operation 732, the assistance or protection third party 170, open a fourth communications session. In the course of an operation 734, the terminal 100 transmits, to the protection site 170, an identifier of the third-party merchant site, for example in the form of an identifier of the page being displayed, and, more particularly, the address of the said page. In the course of an operation 736, the protection site receives the said identifier. In the course of an operation 738, the protection third party transmits to the terminal 100 information relating to the third session. In the course of operation 740, the terminal 100 receives and processes the said information relating to the third session. By way of example, in FIG. 7, a large number of exchanges of information have been represented between the terminal 100 and the protection site 170, in the course of operations 738 to 764. However, in accordance with the third aspect of the present invention, at least one item of information relating to the third session is transmitted in the course of operation 738. In the example illustrated in FIG. 7, complementing the transmission of information relating to the third session carried out by the protection site 170 to the terminal 100 in the course of operation 738, in the course of an operation 742 the terminal 100 requires transmission of the degree of risk, of the degree of punctuality and the degree of satisfaction. The protection site 170 receives this request in the course of operation 744 and transmits these degrees in the course of operation 746. The terminal 100 receives these degrees and displays them to the user in the course of an operation 748. As indicated above, each of these degrees can be based on official satisfaction and fraud statistics (for example country by country or state by state, by means of payment used, by type of transaction in progress, by site, etc.) or available on a network such as the Internet network, and/or on information supplied by visitors to the protection site 170 (see FIG. 16). In the course of an operation 750, the terminal 100 requires transmission of a legal questionnaire. The protection site 170 receives this request in the course of operation 752 and transmits this questionnaire in the course of operation 754. The terminal 100 receives this questionnaire and displays it to the user in the course of an operation 756. The questionnaire may include questions to which it is necessary to respond either automatically, by using the assistance software, or manually, by inputting at the keyboard 105 with a view to keeping a legal trace of the traction. For example, this information may include an identifier of the site 170, an identifier of the user, a transaction date, a purpose of the transaction and a transaction amount. The questionnaire may also include questions the responses to which are optional but which serve to make the user aware of the consequences of the transaction or of the lack of knowledge which he has of the third-party merchant site. The terminal 100 transmits the responses to the questionnaire, and, if appropriate, attached pages which originate from the third session, to the protection site 170 with a request for sequestration, in the course of an operation 758. The protection site 170 receives this information in the course of an operation 760 and encrypts it, adding to it a certified date and a certificate of integrity, and sends it back to the terminal 100, in the course of an operation 762. The terminal 100 receives this encrypted information and the certificate of integrity in the course of an operation 764 and places them in memory on the hard disk 102, and, if appropriate, endowing them with automatic-deletion prohibition (see operation 519). In a variant, the protection site 170 stores a duplicate of this information or the certificate of integrity which makes it possible to detect whether the information held in memory is subsequently altered. In the course of operation 766, the terminal 100 transmits a single-use means-of-payment request to a financial site proposed by the protection site 170. The financial site receives this request in the course of an operation 768. The financial site, in the course of an operation 770, supplies the terminal 100 with information intended to participate in determining a single-use means-of-payment identifier. The identifier of a single-use payment card consists, for example, of the first eight figures of a real payment card and of eight figures supplied by the financial site. It will be observed that the date of expiry of the said card may form part of the information supplied by the financial site and correspond to a code. According to another variant, the assistance software installed on the terminal 100 allows coding of the user's payment card number, by means of a key supplied by the financial site, in such a way that the coded number is subsequently decoded by a financial organization, for example the same financial site, and enables a payment to be made. When the user is already referenced within the financial site, that is to say that a permanent account number is attributed to him, the financial site first of all carries out authentication of the user. Then the third-party financial site does not transmit a whole payment-card number, in order to avoid the possibility of this number being pirated, that is to say used by a third party. In contrast, preferably, the financial site supplies a root which makes it possible to determine an identifier of a payment means by the user or the terminal 100 but does not make it possible, with the root alone, to constitute a means-of-payment identifier. This characteristic is the opposite of the method of operation described in the U.S. Pat. No. 5,883,810 which is entirely incorporated here by reference. The root supplied by the financial site and/or the determination of the identifier of the single-use means of payment depend, preferably, on identifiers of the financial transaction, such as its amount, the identifier of its payee and/or the identifier of the financial site. The root supplied by the financial site may be generated as a transaction certificate for the transaction in progress. The terminal 100 receives the information intended to participate in determining a single-use means-of-payment identifier in the course of operation 772. It determines the single-use means-of-payment identifier in the course of operation 774, for example by implementing a one-way calculation function of the assistance software, acting on the information received from the financial site, of a payment-card number, of an identifier of the site 150 and of a transaction amount. If appropriate, a transaction certificate is also used to determine the single-use means-of-payment identifier. In the example illustrated in FIG. 7, in the course of operation 776, the terminal 100 and, in the course of operation 778, a third-party confidence site 180 open a fifth communications session. In the course of an operation 780, the terminal 100 transmits information to be sequestered to the third-party confidence site. This information is legal information relating to the transaction carried out with the third-party merchant site. In the course of an operation 782, the third-party confidence site 180 places this information in memory, possibly encrypted and accompanied by a certificate of integrity. In the example illustrated in FIG. 7, in the course of an operation 784, the protection site 170 transmits a security-protection message to the third-party merchant site in order to confirm that the transaction has been security protected. It will be observed in FIG. 7 that the protection site 170, financial site and third-party confidence site 180 have been represented as independent entities. However, in other embodiments of the method of the present invention, two or three of these sites are combined into a single entity. It will be observed that the site known as financial site can serve only as intermediary between the parties to the transaction (the user and the third-party merchant site) and have the payment made by another financial body, after having supplied it with an identifier of the user or of a real or virtual means of payment. In particular, the site known as financial site can use the root which it has transmitted and, if appropriate, information which it has received on the part of the terminal 100, in order to determine a permanent payment-card number. For example, if the key transmitted is a series of figures which have to be added to the figures of the permanent payment-card number in order to supply, modulo 10, the figures of the single-use means-of-payment identifier, the key kept by the financial site can serve it for determining the permanent payment-card number. It will be observed that all the communications employed in accordance with the present invention are preferably protected by encryption, according to known or future techniques. FIG. 8 represents functions implemented in various computer systems linked to a communications network in the course of a first example of a succession of operations implemented in accordance with the fourth aspect of the method envisaged by the present invention, in the case in which the user is referenced with the financial site. It will be observed in FIG. 8 that, in the course of an operation 800, the terminal 100 is connected to the financial site and that a communications session is in place. In the course of an operation 801, the financial site and the terminal 100 organize the encryption of the communications. Next, in the course of an operation 802, the financial site authenticates the user of the terminal 100 in a known way, for example by asking him for a confidential access code and by checking this code. Next, in the course of an operation 803, the financial site determines the single-use means-of-payment identifier root. This root is preferably related to an identifier of the user and kept with this identifier in a memory (not represented) of the financial site. For example, this root represents the last eight figures of a payment-card number to be supplied to a merchant site such as the merchant site 150 or the third-party merchant site. According to other embodiments, the key is a coding key used by software resident in the terminal 100 in order to generate a means-of-payment identifier. In the course of an operation 804, the root is supplied to the terminal 100. In the course of an operation 805, the root is validated in memory of the financial site, in a list of valid roots. According to one variant, the financial site determines the single-use means-of-payment identifier which the terminal 100 is going to use. For example, the financial site knows the first eight numbers of a payment card and adds to them the last eight numbers which it supplies to the terminal 100 or the coding function and the roots used by the terminal 100. This identifier is then kept in a memory of valid identifiers. The communications session with the terminal 100 is then broken off. When the merchant site wants to be paid, it supplies a means-of-payment identifier to the financial site. In the course of a test 806, the financial site determines whether or not it has received a means-of-payment identifier. When the result of the test 806 is negative, test 806 is reiterated. When the result of test 806 is positive, in the course of a test 807, the financial site determines whether or not the means-of-payment identifier is valid. To that end, for example, the financial site extracts the root which it has supplied and compares it with the roots held in the list of valid roots. According to another example, the financial site compares the identifier which it receives with the elements of a list of valid identifiers which it has determined. When the result of test 807 is positive, in the course of an operation 808, payment is made. When the result of the test 807 is negative or when the payment operation 808 is completed, in the course of an operation 809, the root of the identifier or the identifier itself is invalidated in the memory of the financial site so that this root or this identifier cannot be used for a payment. In a variant, the user, in the course of operation 803, supplies information relating to the transaction, such as the name of the company which is managing the merchant site, for example (supplied by the protection third party 170, for example) or the amount of the transaction and the identifier of the single-use means of payment is determined so as to be representative of this information or to be associated, in the memory of the financial site, with this identifier. In this way the transaction can be authenticated by the financial site, in the course of operation 807, prior to payment, in the course of operation 808. FIG. 9 represents functions implemented in various computer systems linked to a communications network in the course of a second example of a succession of operations implemented in accordance with the fourth aspect of the method envisaged by the present invention, in the case in which the user is not referenced with the financial site. It will be observed in FIG. 9 that the operations 901 to 903, 905 to 909 and 911 correspond respectively to the operations 800 to 807 and 809. Following operation 903 and before operation 905, in the course of an operation 904, the terminal 100 supplies the financial site with a permanent means-of-payment identifier, such as a payment-card number. Following the test 909, when it is positive, in the course of an operation 910, the financial site uses the means-of-payment identifier which it has received from the terminal 100 in the course of an operation 904 in order to obtain payment from the financial body which issued the permanent payment means. This payment is made either for the benefit of the merchant site which has supplied the single-use means-of-payment identifier, or for the benefit of the financial site, which, then, makes payment for the benefit of the merchant site which supplied the single-use means-of-payment identifier. FIG. 17 represents functions implemented in various computer systems linked to a communications network in the course of a third example of a succession of operations implemented in accordance with the fourth aspect of the method envisaged by the present invention, in the case in which the user is not referenced with the financial site. It will be observed in FIG. 17 that the operations 1701, 1702 are identical to operations 901 and 902. Following operation 1702, in the course of operation 1703, the financial site determines a root or a calculation code and, in the course of an operation 1704, the financial site supplies this root or this code to the terminal 100 so that the latter may determine the single-use means-of-payment identifier. This code may be predetermined, being, for example, fixed for a predetermined duration, randomly take a value from among several possible values, or depend on information relating to the transaction, such as the name, the telephone number or the address of the user or the address of the retailing site on the communications network. It will be observed that the code is preferably employed in the terminal 100 in such a way that a permanent means-of-payment identifier can be determined by knowing the root or code and the single-use means-of-payment identifier. Once the session between the financial site and the terminal 100 is completed, the terminal 100 uses the root or code supplied by the financial site in the course of operation 1704 in order to determine a means-of-payment identifier according to known numerical techniques. When, in the course of an operation 1705, the financial site receives a means-of-payment identifier, it also receives information relating to the transaction. The financial site can thus determine the generator code or the root which it has supplied in the course of operation 1704, even if this code depends on information relating to the transaction. In the course of a test 1706, the financial site determines whether this code is valid and whether the permanent-use means-of-payment identifier is valid. If the two are valid, operation 1707 is carried out. Otherwise operation 1708 is carried out. Operations 1707 and 1708 correspond to the operations 910 and 911. According to a variant, not represented, the expiry date relating to the single-use means-of-payment identifier makes it possible to identify a generator code or a root. FIG. 16 represents a flowchart for operation of the device illustrated in FIG. 1, for implementing the fifth aspect of the present invention. This aspect may or may not be combined with certain other aspects of the present invention. In the course of an operation 1601, the user of the terminal 100 determines a date at which he considers he would be satisfied to have been supplied the product or service which he has paid for on the communications network 120. Next, the central processing unit 106, implementing the assistance software, looks out for the arrival of the selected date, in the course of an operation 1602, which may extend, as a background task, over several days. When the date arrives, in the course of an operation 1603, the central processing unit 106 causes a dialogue window to be displayed on the visual-display screen 104, asking whether the product or service has actually been supplied. Whether the response is positive or negative, another question asks the user for the degree of satisfaction or dissatisfaction he feels regarding the supply of the product or service supplied, in the course of an operation 1604. Moreover, when the response is negative, a new date is requested from the user and the process is renewed. The satisfaction information and any new date are placed in memory 102 by the terminal 100, in the course of an operation 1605. When, in the course of an operation 1606, the terminal 100 is connected to the network 120, and whatever the site to which the terminal is connected, a satisfaction message including the identifier of the merchant site and the degree of satisfaction of the user, as well as the delivery timescale, is automatically transmitted to the protection site 170 in the course of an operation 1607. This message may take the form of electronic mail ("e-mail"), or any other form recognized by the protection site 170. By virtue of this message, the protection site 170 can determine the merchant sites which it can recommend to its visitors. FIG. 10 represents what is displayed by the visual-display screen 104 when the user of the terminal 100 has selected a sales offer from the remote data site 150 and when this user is ready to make on-line payment, by supplying information relating to a payment card such as the number and the expiry date of the payment card. In a simplified way, the visual-display screen 104 then displays: a main portion 1000 which represents a portion of a page received originating from the remote data site 150; an upper bar 1010 which displays, and makes it possible to select, scrolling menus or functions; a lower bar 1050 which displays general information and function-selection areas and a side bar 1080 which makes it possible to scroll the page displayed in the main portion 1000. In the example illustrated in FIG. 10, the main portion 1000, in the course of the phase of the transaction which corresponds to the start of an on-line payment, includes: a portion of a received page originating from the remote data site 150 including textual information on a sales offer 1020, possibly graphics or image information (not represented), and is associated with an audio sequence (not represented); information 1030 for selection of at least one other page of the remote data site 150; terms of business 1035; a moveable icon 1090 representing the position selected by the mouse 103 and a central portion for on-line payment 1040. The central portion 1040 includes, for example, boxes 1041 for selecting a type of payment card, an area 1042 for writing a payment-card number, an area 1043 for writing a month of expiry of the duration of validity of the payment card and an area 1044 for confirming the input of the information relating to the electronic on-line payment and the transaction. The upper bar 1010 displays two lateral arrows 1084 which, when one of them is selected by the use of the mouse 103, makes it possible to return to the previously displayed page in the central portion 1000 (arrow pointing to left) or to move forward to the page displayed after the page being displayed in the central portion 1000 (arrow turned to the right) according to the conventions known in the Internet browser software. The upper bar 1010 also displays headers of scrolling menus which are well known in the browser software, such as: "file", in order to create, open, save, print or close a file, "edit", in order to select, cut or paste information, "Internet access", in order to search for an Internet site or to connect to it using its address, "messaging" in order to gain access to his personal messaging service, and "favorite sites", in order to directly access Internet sites previously selected as favorite sites. The use of the mouse 103 makes it possible to select one of the functions or one of the scrolling menus illustrated (sometimes in the form of icons) in the upper bar 1010. The side bar 1080 includes: an upper arrow 1082 turned upwards, selection of which causes scrolling of the page illustrated in the main portion 1000, upwards, so as to display the upper part of it, a lower arrow 1083 turned downwards, selection of which causes scrolling of the page illustrated in the main portion 1000, downwards, in order to display its upper part, a portion 1081 which, in combination with a portion 1085, represents the proportion of the page illustrated in the main portion 1000 which is displayed and a portion 1085 which, with the same proportionality factor as the portion 1081, represents the lower part of the page illustrated in the main part 1000 which is not visible. The bottom strip 1050 displays general information, such as the name of the access provider, the duration of the connection to the access provider already expired, the browser used (for example one of the trademarks Netscape, Microsoft or AOL), and the function-selection areas. Here, two function-selection areas 1060 and 1070 trigger backing-up of at least one item of content information of at least the portions of the pages of the remote data site 150 which have been received from the remote data site 150 and displayed on the visual-display screen 104. The area 1060 displays the back-up function, in clear, in the form of two words: "business back-up". The area 1070 displays the back-up function, in the form of an icon representing scales, the symbol of justice. According to some variants of the present invention: only the portions which have been displayed, only content or context information, such as the name of the provider and the date of the transaction, only certain words present in or representative of these portions or the sound file received and distributed, only the texts present in these pages, the texts and the images, | ||||||