System for authenticating users and devices in on-line transaction networks

Abstract

A method for efficiently protecting transactions and providing authentication of users and devices in on-line systems that transfer funds electronically, dispense cash, or provide a good or permit a service to be utilized is provided. The transaction may be initiated by a magnetic-striped plastic card at an attended or unattended terminal (10, 11, 12) and requires the entry of a preassigned Personal Identification Number through a keyboard (20). The Personal Identification Number is encrypted (23) more than once at the terminal and other means are used in order to prevent the utilization of certain tapped-line data. The data required to validate and authorize the transaction is transmitted securely to a centralized computer (14) which accesses from its stored data base (15) the data that is required to decrypt and validate the transaction, including the encrypted Personal Identification Number corresponding to the received transaction data. A secret Terminal Master Key must be maintained securely at each terminal and may differ at each terminal. A list of such Terminal Master Keys and other secret data must be securely maintained at the centralized computer. Means for multiple-encryptions and decryptions in a predetermined way must also be maintained at each terminal and at the centralized computer. Means (34) are provided for securely returning a response to the terminal at which the transaction was initiated to authorize or reject the requested transaction. These functions are accomplished in a way that permits efficient utilization of data communications lines and reduces or eliminate perpetration of fraud by any of various means.

Claims

I claim:

1. In a system for authenticating users and devices in on-line transaction networks comprising a plurality of remote terminals in communication with a central processing unit including a data base containing encrypted data used in the authentication of the users and devices, said data being encrypted with a master key and including terminal master keys for each of said remote terminals and identification numbers for each of said users all of which are secret, said data further including terminal identification numbers for each of said remote terminals and account numbers for each of said users, wherein each of said remote terminals is provided with means for entering an account number and an identification number of a user initiating a transaction as well as the nature of the transaction, the improvement in a method for protecting the transaction comprising the steps of:

generating at a terminal a transaction request message based on the information entered at the terminal by a user initiating a transaction,

using the identification number and the account number entered by the user and the terminal identification number and the terminal master key, and employing such variants as to generate a working key unique to each transaction,

encrypting the transaction request message using the working key,

transmitting the encrypted transaction request message,

deriving the working key at the central processing unit using information derived from the transmitted message and the data base including the account number, the terminal master key and the terminal identification number,

decrypting the message received at the central processing unit using the working key,

comparing the user identification number and account number obtained by decrypting corresponding data in the data base with the data in the transaction request message to validate the transaction request message,

generating a transaction request response and encrypting the transaction request response with the working key,

transmitting the encrypted transaction request response to the terminal where the transaction was initiated, and

decrypting the message received at the terminal using the working key and, if the transaction is approved, providing the requested service.

2. The method of protecting a transaction as recited in claim 1, further comprising the step of appending the account number to the encrypted transaction request message prior to transmitting and wherein the step of deriving the working key is performed by generating the working key using the appended account number, the user identification number, the terminal identification number and the terminal master key.

3. The method of protecting a transaction as recited in claim 1, further comprising the steps of generating a transmitted key using the working key and appending the transmitted key to the encrypted transaction request message prior to transmitting and wherein the step of decrypting the message is performed using the appended transmitted key to obtain the working key, the working key then being decrypted to obtain the user identification number.

4. The method of protecting a transaction as recited in claim 3, further comprising the steps of:

after decrypting the message received at the terminal, generating and transmitting an acknowledgement to the central processing unit, and

destroying the working key at the terminal and the central processing unit after acknowledgement.

5. The method of protecting a transaction as recited in claim 4, wherein said acknowledgement is encrypted using the working key.

6. The method of protecting a transaction as recited in claim 3, wherein the step of generating the working key comprises the steps of:

using the user identification number and account number entered at the terminal, generating a first security parameter,

generating a secondary key by encoding the terminal identification number using the terminal master key, and

using the first security parameter and the secondary key to generate the working key.

7. The method of protecting a transaction as recited in claims 3 or 6, wherein the time of day is also used to generate the working key.

8. The method of protecting a transaction as recited in claim 6, wherein the time of day is used to generate the first security parameter and at the central processing unit, further comprising the step of decrypting the first security parameter using the working key to obtain the time of day, the transaction not being approved if the decrypted time of day varies by more than a predetermined time period from the time of day at the central processing unit.

9. The method of protecting a transaction recited in claim 4, further comprising the step of updating the data base at the central processing unit after acknowledgement.

10. The method of protecting a transaction as recited in claim 3, wherein each of said terminals includes a card reader for reading a user card encoded with the user account number, the card being inserted in the card reader in order to initiate a transaction and the user then entering a user identification number.

11. The method of protecting a transaction as recited in claim 10, wherein the card encoded with the user account number also has an anti-counterfeiting feature, and the step of generating a working key comprises the steps of:

using the user account number and identification number, the anti-counterfeiting feature and the time of day, generating a first security parameter,

generating a secondary key by encoding the terminal identification number using the terminal master key, and

using the first security parameter and the secondary key to generate the working key.

12. The method of protecting a transaction as recited in claim 6, wherein the step of generating the working key further comprises the steps of:

using the first security parameter and the secondary key, generating a second security parameter, and

using the second security parameter and the secondary key to generate the working key.

13. The method of protecting a transaction as recited in claim 12, wherein the step of generating the transmitted key comprises the steps of:

generating a third security parameter using the working key and the secondary key, and

generating the transmitted key using the third security parameter and the secondary key.

14. The method of protecting a transaction as recited in claim 13, wherein the step of decrypting the message received at the central processing unit comprises the steps of:

multiply decrypting the transmitted key to first obtain the third security parameter and then the working key, and

decrypting the transaction request message using the decrypted working key.

15. The method of protecting a transaction as recited in claim 10, wherein after the step of comparing the user identification number and account number, if the transaction is not validated, comprising the further step of requesting that the user identification number be re-entered to re-initiate the transaction.

16. The method of protecting a transaction as recited in claim 15, wherein the card is retained in the card reader and not returned to the user if the step of requesting the user identification to be re-entered is repeated a predetermined number of times.

17. The method of protecting a transaction as recited in claim 3, wherein the on-line transaction networks comprise a plurality of central processing units each in communication with other central processing units, each of said central processing units having an identification number which is used to obtain a secret interchange master key and a secret password, further comprising the steps in an interchange transaction between central processing units of:

using the interchange master key and the password to generate an interchange working key,

encrypting the terminal identification number and the terminal master key using the interchange working key to generate an interchange transmitted key and appending the interchange transmitted key to the encrypted transaction request message, and

transmitting the encrypted transaction request message with the appended interchange transmitted key to a second central processing unit.

Description

BACKGROUND OF INVENTION

1. Field of the Invention

This invention relates to the secure generation and transmission of Transaction Request Messages and Responses in on-line Electronic Funds Transfer and other types of networks consisting of remote terminals in communication with a central data base containing encrypted data used in the validation or authentication process or similar networks used to transfer funds and that provide for, in addition to transferring funds, dispensing cash, paying bills, making deposits, dispensing a good or permitting utilization of a service.

2. History of the Prior Art

Both on-line and off-line computer networks and systems have been developed for executing user initiated or requested financial transactions for reasons of public convenience and economy. One example is a cash dispensing machine. Such a machine may be activated by use of an appropriately coded check or other negotiable instrument, or a plastic credit, debit or identification card, and dispenses the requested amount of cash if the request seems valid to the authenticating means in the cash dispensing device.

One type of on-line system stores account information in a central data base to which the remote terminals are connected by data communication lines. In response to submission of specified information from a remote terminal, such as account number, amount of sale or amount requested, merchant identification if a sale, and secret information related to the cardholder, the system searches the account files to obtain data that may indicate that the transaction should be approved or denied. Such information may include date of last use, amount of credit if a credit transaction, balance in account, whether a card has been lost, stolen or has expired. If the transaction is approved, the system adjusts the account information appropriately after the transaction is completed. As the art progressed, terminals with increased functions were provided that permitted more functions to be performed than dispensing cash or effecting a purchase. For instance, financial institutions, to reduce peak loads and to extend their services during times of business closure, permit the transfer of funds between accounts, accept payments for utilities or for loan balances, accept deposits, and provide for advances to be charged to valid credit cards. These devices typically include a plastic card reading mechanism, a keyboard, a display, document entry and exit apertures and may be connected to a data base or operate as a stand-alone device. Due to the increased functions permitted, the exposure to fraud increased, so that secret numbers (Personal Identification Numbers) were issued to cardholders to reduce the exposure. The Personal Identification Number entered on the keyboard by the cardholder must either compare directly with the number encoded on the magnetic stripe of the plastic card or some correspondence, that may depend on encryption, must exist between the Personal Identification Number and the number encoded on the magnetic stripe. Otherwise, the transaction is not enabled on the presumption that the card was either lost or stolen. This method may be used by stand-alone devices or devices connected to a central data base.

The use of a Personal Identification Number improved the security of such systems but still left some means available for fraud and had other disadvantages. The problem of secure issue of Personal Identification Numbers arose. The use of on-line files with lists of Personal Identification Numbers may permit unauthorized access to the files by employes for purpose of obtaining what is supposed to be secret information. With such information, duplicate or counterfeit cards can easily be manufactured to perpetrate fraud. Several different approaches were taken to overcome the disadvantages. One approach, to avoid the use of on-line files and to overcome the supposed cost and complexity of on-line systems, was to try to improve the security of stand-alone use. As a result, special plastic cards with material laminated into the card, pasted onto the card, holes punched into or onto the card as a security measure, were devised, none of which was effective by itself.

Another approach was to encrypt the Personal Identification Number stored in the account records, which is effective, provided appropriate additional security measures are instituted. Encryption may not be effective with stand-alone devices because of access required by maintenance personnel and for replenishing the cash supply or other servicing, thereby exposing the encryption key to simple means of compromise. Encrypting only the secret information in the central account records is not effective since the secret information must also be entered at a remote terminal to initiate a transaction and be transmitted, usually by means of utility communication lines, to the centralized computer, thereby becoming subject to monitoring by person or persons unknown. The transmission therefore must also be encrypted, which is effective but may still permit someone who can break the code access to the list of correspondence between account information and Personal Indentification Numbers by monitoring these transmissions. An additional shortcoming is the generation, by a sophisticated penetrator, of spurious transactions to fraudulently transfer funds within data base accounts. As a result, the previous methods of validating the secret number at a centralized data processor provide protection against casual fraud but may not provide adequate protection against a penetrator having knowledge of, and perhaps, access to, current data processing equipment or systems. Alternatively, those methods that seem to provide an adequate level of security also seem quite costly due to the need for utilizing high-cost data communication lines for multiple transmissions for validation of each transaction and for transmission in a secure way of the required enciphering keys, rather than relying on a single Transaction Request Message, a single Response and an acknowledgement or some minimum number of transmissions per transactions.

There has evolved within the same time frame networks other than the proprietary networks that a single financial institution may deploy to service its customers. Financial Institutions may decide to share networks or to interchange transactions in order to provide better service. There are national networks developed by Bank Cards to service many financial institutions that may aggregate millions of accounts and millions of transactions per day. Although each transaction may be small, the aggregate dollar volume transferred per day is substantial. In addition, there are the semi-official clearing house systems and the networks used by Federal Financial Agencies to transfer billions of dollars of funds daily and that impact the financial structure of the country. The methods used by some of the large financial institution networks to provide security are so simplistic, they may easily be defeated by a knowledgeable person, as occasional newspaper headlines attest.

What has been lacking until now is a procedure, method or system that integrates the validation and authentication of the plastic card, cardholder, terminal or other device used to initiate transactions, render ineffective wiretap data, that does not require unencrypted Personal Identification Numbers to be processed, that efficiently uses costly data communication lines by minimizing transmissions and is adaptable to the requirements of different types of on-line networks.

SUMMARY OF INVENTION

A system in accordance with the present invention consists of a means for multiply-enciphering secret and other data in a predetermined way at a remote terminal or a computer connected by communication lines to a computer, said enciphering to provide authentication of the card, cardholder, terminal or other device, and to provide security against intrusion by wiretapping in a way that maximizes utilization of communication lines. The secret data may be entered on a keyboard by an authorized cardholder together with other data that may be required to complete the transaction. The secret and other data, and data internal to the remote terminal or computer, are multiply-enciphered in a predetermined way using a secret Terminal Master Key stored in the terminal or computer, initially to generate a Working Key that is used only to encipher the Transaction Request Message that is generated within the terminal or computer by suitable means. The Working Key is then additionally multiply-enciphered in a predetermined way using the secret Terminal Master Key to generate a Transmitted Key that is appended to the Transaction Request Message and transmitted by suitable means to the computer at the centralized account data base in a way that prevents intrusion by wire tapping. At the centralized computer, the account data base is searched to find enciphered and other data corresponding to the account of the authorized cardholder and the device from which the message was received, which data is used two ways. Part of the data is used to facilitate the multiple decipherments of the Transmitted Key in order to obtain the Working Key. Other parts of the data are used to validate and authenticate the transaction after it has been deciphered using the Working Key and the Working Key itself has been further multiply-deciphered and in a way that provides that the enciphered data is protected from access by employees of the financial institution such as programmers, systems analysts, operators and also protected from other sophisticated penetrators who may gain unauthorized access to the computer network or system. After the transaction has been validated, additional tests of an accounting nature may be performed by the central computer to determine whether the Transaction Request should be approved, tests depending upon data such as balance in account, date of last use, amount withdrawn and other data. An appropriate response is generated at the centralized computer by suitable means, which response is enciphered in the same Working Key used to encipher the Transaction Request Message. This Transaction Request Response is transmitted by suitable means to the terminal or computer from which the Transaction Request Message was received, where it is deciphered by suitable means using the Working Key that has been securely stored and the requested transaction is completed if approved, or an indication displayed that the transaction is not approved. After completion of the transaction, the terminal or computer may send an acknowledgement to the centralized computer indicating the type of transaction completed, as an added security measure, which acknowledgement may be enciphered using the same Working Key. After the centralized computer receives the acknowledgement, it updates the accounting data base and then the remote terminal or computer and the centralized computer destroy the Working Key securely by resetting the register or location in which the Working Key has been stored to prevent reuse or compromise.

Because the secret data and other data are used to generate the working key required to encipher each Transaction Request Message, each such Message will be enciphered using a different Working Key before being transmitted to the centralized computer, substantially enhancing the strength of the enciphering means and protecting the Terminal Master Key from compromise by statistical cryptanalysis. In the preferred embodiment, there is only 1 chance in 2 to the 56th power that the same Working Key would be generated twice.

BRIEF DESCRIPTION OF DRAWINGS

A better understanding of the invention may be had from a consideration of the following detailed description considered in conjunction with the accompanying drawings in which:

FIG. 1 is a functional block diagram representation of a typical on-line financial network in which the present invention may be implemented.

FIG. 2 is an operational block diagram that provides an overview of the system description of the present invention.

FIG. 3 is a representation of one method of forming Security Parameter 1 at a terminal or computer to initiate the process of the present invention.

FIGS. 4, 5, 6 are alternative methods of forming Security Parameter 1 to suit the needs or characteristics of different types of financial, on-line networks.

FIGS. 7A, 7B and 7C are a detailed, operational block diagram of the overall method or process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Terminal: A device such as a Cash Dispenser, Automatic Teller Machine, Point-of-Sale device, or any of various types of computers that may be used to initiate a financial transaction.

Terminal Identification (TID): A designation of 8--8 binary digit numbers, letters or a mixture of numbers and letters that identifies a specific terminal and is embodied as an integral characteristic of the terminal.

Primary Account Number (PAN): A designation that identifies an account holder in an accounting data base.

Personal Identification Number (PIN): A variable number of digits, letters or a mixture of digits and letters known only to an authorized account holder and used in the initiation and validation of on-line financial transactions. In the preferred embodiment, at least 4 characters are used as the Personal Identification Number. The binary designation chosen for these and other parameters may be any of those commonly used in computer processing or data communications without affecting the scope of the invention.

Card anti-counterfeiting features (CS): A designation or identification for a magnetic-striped, plastic, size "A" card that cannot be changed without destroying the card.

Encryption or Decryption Keys: Some embodiments of the Data Encryption Standard require a secret 56 binary digit key to particularize or control the operation of the algorithm, some embodiments require that 64 secret binary digits be entered into the key register even though only 56 enter into the operation of the algorithm and the remaining 8 are odd parity binary digits, one for each 7 binary digits of the key and each parity binary digit located to the right of each 7 binary key digits. Either of these is within the scope of the invention, as are other cryptographic systems which require or permit a secret encryption key to control or particularize the operation of the cryptographic algorithm.

Master Key (KMO if at a centralized computer, KMT if at a terminal): A key used primarily or solely to encrypt and decrypt other keys.

Master Key Variants (KM1 and KM2 if at a centralized computer, KMT1 and KMT2 if at a terminal): A Master Key with certain specified binary digits inverted to provide a defense against specific types of penetration by an intruder. In the 56 binary digit representation, KM1 and KMT1, called the first variants, are equal to the respective Master Keys with binary digits 2, 9, 16, 23, 30, 37, 44, 51, counting left to right, inverted. Then, KM2 and KMT2, called the second variants, are formed from the respective Master Keys by having binary digits 5, 12, 19, 26, 33, 40, 47, 54 inverted.

Working Key (WK): A key used to encrypt or decrypt a Transaction Request Message. In this invention, it differs for each transaction to provide an enhanced degree of security.

Transmitted Key: A key transmitted with a transaction and used to provide a defense against wire tap and used to facilitate decryption.

Encrypt data Y using key X: E[X](Y)

Decrypt data Y using key X: D[X](Y)

Encrypt under Master Key:

E[KMO] (Key) at centralized computer;

E[KMT] (Key) at terminal.

Decrypt under Master Key:

D[KMO] (Key) at a centralized computer;

D[KMT] (Key) at a terminal.

Reencrypt from Master Key (RFMK(X,Y)): Defined as; E[D[KM1](X)](D[KMO](Y)).

Reencrypt to Master Key (RTMK(X,Y)): Defined as: E[KMO](D[D[KM2](X)](Y)).

Inverse Reencrypt from Master Key (RFMK.sup.-1 (X,Z)): Defined as; E[KMO](D[D[KM1](X)](Z)).

Inverse Reencrypt to Master Key (RTMK.sup.-1 (X,W)): Defined as; E[D[KM2](X)](D[KMO](W)).

Concatenation, specified by ".parallel." (Double Bar): Joining of subfields together to form a field by juxtaposing the subfields, for instance AB.parallel.CD=ABCD.

Description of the Preferred Embodiment

Referring now to the drawings, and more particularly to FIGS. 1 and 2, the invention will be described in terms of a preferred embodiment. This embodiment comprises a network having cash dispensing machines, automatic teller machines or the like such as would be used by a bank or similar financial institution. It is to be expressly understood, however, that the invention has broad and general applications including, but not limited to, transferring funds, dispensing a good or permitting the utilization of a service.

A cardholder enters his magnetic striped size "A" plastic card into an attended or unattended financial terminal 10, 11, 12, enters his Personal Identification Number and amount requested or amount of transaction on a keyboard at 20. The terminal reads the magnetic stripe and extracts the Bank Identification Number, the Primary Account Number and adds the Terminal Identification at 21. The terminal generates the Transaction Request Message at 22 and uses the Primary Account Number, the Personal Identification Number, the card anti-counterfeiting feature number and the Time field to generate Security Parameter 1, which is used with the Terminal Identification and the Terminal Master Key within the encryption means to generate the Working Key at 23 in a manner to be explained with reference to FIGS. 7A to 7C. The Working Key is used to encrypt the Transaction Request Message at 24 already generated. The Working Key, the terminal Identification and the Terminal Master Key are used to generate the Transmitted Key at 25 in a manner to be explained with reference to FIGS. 7A to 7C. The Transmitted Key is appended to the Transaction Request Message in addition to transit, routing and other control information that may be required such as an Initialization Vector required to initialize the DES in some usages, and the complete message is transmitted to the centralized computer 14 at 26 by transmission means.

The centralized computer 14 obtains data, some of it encrypted, from the accounting data base 15 using the control information in the message header and other information and sends it all to the Security Module 13 at 27. The Security Module 13 uses the Terminal Identification, the Terminal Master Key and Transmitted Key within the encryption means to obtain the Working Key at 28 in a manner to be described with reference to FIGS. 7A to 7C. The Working Key is used within the Security Module 13 to decrypt the Transaction Request Message at 29. The Security Module 13 uses the Working Key, the Terminal Master Key and the Terminal Identification within the encryption means to obtain Security Parameter 1 in a manner to be explained with reference to FIGS. 7A to 7C in order to obtain access to the Personal Identification Number and card anti-counterfeiting feature number at 30. The Security Module 13 verifies that the Personal Identification Number and card anti-counterfeiting feature number that was generated from the data in the message is the same as those values contained in the accounting data base transferred from the centralized computer by any one of several means at 31, and notifies the centralized computer 14.

The centralized computer 14 executes the remainder of the approval process at 32, generates and transmits to the Security Module 13 the appropriate response at 33. The Security Module 13 encrypts the response using the Working Key at 34, after which the response is transmitted to the terminal 10, 11 or 12 by transmission means. The terminal decrypts the response using the Working Key at 35, provides the service requested at 36, generates an acknowledgement at 37, encrypts the acknowledgement using the Working Key at 38 and transmits it to the centralized computer 14. The centralized computer 14 sends the acknowledgement to the Security Module 13 at 39. The Security Module 13 decrypts the acknowledgement using the Working Key, notifies the centralized computer 14 and destroys the Working Key at 40. The centralized computer 14 updates the account base 15 at 41, the terminal 10, 11 or 12 updates and writes the magnetic stripe on the plastic card if required, destroys the Working Key at 42, completing the transaction at 43. With reference now to FIGS. 7A to 7C, the present invention may be implemented on a financial transaction or transfer network such as that represented in FIG. 1 that contains attended or unattended terminals 10, 11, 12 or a computer 16 with transmission and encryption means and associated Security Module 17 and data base 18 connected by data communication lines to a centralized computer with transmission means 14, encryption means 13, and with access to a centralized accounting data base 15, which may be any one of several media for storing, retrieving and changing data usually by magnetic or electromagnetic means. The accounting data stores information related to each account assigned to authorized account holders of the Financial Institution. The terminals or computer may be connected to the centralized computer by any of various means familiar to those skilled in the art. In order to initiate a transaction on such a network, an authorized cardholder enters his magnetic striped, size "A" plastic card into a card entry means at the terminal 50 as shown in FIG. 7A, the terminal determines whether the cardholder has been requested to enter his Personal Identification Number more than a fixed number of times at 51, in the preferred embodiment three times. If the cardholder has entered his Personal Identification Number three times, the terminal retains the card at 52, indicates that the cardholder must visit his Financial Institution at 53 and terminates the transaction at 54.

If the cardholder has not entered his Personal Identification Number three times, the terminal requests the cardholder to enter his Personal Identification Number on the keyboard at 55, which the cardholder does at 56, the terminal reads the magnetic stripe at 57, the terminal forms Security Parameter 1 at 58 by using part of the Primary Account Number, part of the Personal Identification Number, part of the card anti-counterfeiting number and part of the Time field as shown in FIG. 6 or alternatively as shown in FIGS. 3, 4, 5. The terminal requests the cardholder to enter the type of transaction and the amount at 59, which the cardholder does at 60, the terminal generates the Transaction Request Message at 61. The terminal generates a Secondary Key by decrypting the terminal identification using the Terminal Master Key at 62:

SK=D[KMT](TID). (1)

The terminal generates Security Parameter 2 using function Reencrypt from Master Key and operands Secondary Key and Security Parameter 1 at 63 as specified below:

RFMK(SK,SP1)=E[D[KMT1](SK)](D[KMT](SP1))=SP2, (2)

one implementation of which is shown in Table 1.

                                      TABLE 1
    __________________________________________________________________________
    FUNCTION: REENCRYPT FROM MASTER KEY, RFMX (X, Y)
                    KEY      PLAIN TEXT
                                      CIPHER TEXT
    OPERATION
            OPERAND REGISTER-KR
                             REGISTER-PTR
                                      REGISTER-CTR
    __________________________________________________________________________
    LOAD    KM0 into KR
                    KM0
    LOAD    Y into PTR       Y
    DECRYPT                           D[KM0] (Y)
    STORE   CTR
    GENERATE
            KM1 in KR
                    KM1
    LOAD    X into PTR       X
    DECRYPT                           D[KM1] (X)
    GENERATE
    ODD PARITY
            CTR
    TRANSFER
            CTR to KR
                    D[KM1] (X)
    LOAD    PTR              D[KM0] (Y)
    ENCRYPT                           E[D[KM1] (X)] (D[KM0] (Y))
    CLEAR   KR      0
    __________________________________________________________________________

                                      TABLE 2
    __________________________________________________________________________
    FUNCTION: REENCRYPT TO MASTER KEY, RTMX (X, Y)
                    KEY      PLAIN TEXT
                                       CIPHER TEXT
    OPERATION
            OPERAND REGISTER-KR
                             REGISTER-PTR
                                       REGISTER-CTR
    __________________________________________________________________________
    LOAD    KM0 into KR
                    KM0
    GENERATE
            KM2 to KR
                    KM2
    LOAD    X into PTR       X
    DECRYPT                            D[KM2](X)
    GENERATE
    ODD PARITY
            CTR
    TRANSFER
            CTR to KR
                    D[KM2](X)
    LOAD    Y into PTR       Y
    DECRYPT                            D[D[KM2](X)](Y)
    LOAD    KM0 into KR
                    KM0
    TRANSFER
            CTR to PTR       D[D[KM2](X)](Y)
    ENCRYPT                            E[KM0](D[D[KM2](X)](Y))
    CLEAR   KR      0
    __________________________________________________________________________

                  TABLE 3
    ______________________________________
                        TERMINAL MASTER
    TERMINAL IDENTIFICATION
                        KEY (ENCRYPTED)
    ______________________________________
    TID 1               KMT 1
    TID 2               KMT 2
    TID 3               KMT 3
    TID 4               KMT 4
    0                   0
    0                   0
    0                   0
    TID n               KMT n
    0                   0
    0                   0
    0                   0
    ______________________________________

                                      TABLE 4
    __________________________________________________________________________
    FUNCTION: INVERSE REENCRYPT TO MASTER KEY, RTMK.sup.-1 (X, W)
                    KEY      PLAIN TEXT
                                      CIPHER TEXT
    OPERATION
            OPERAND REGISTER-KR
                             REGISTOR-PTR
                                      REGISTER-CTR
    __________________________________________________________________________
    LOAD    KM0 into KR
                    KM0
    LOAD    W into PTR       W
    DECRYPT                           D[KM0] (W)
    STORE   CTR
    GENERATE
            KM2 in KR
                    KM2
    LOAD    X into PTR       X
    DECRYPT                           D[ KM2] (X)
    GENERATE
    ODD PARITY
            CTR
    TRANSFER
            CTR to KR
                    D[KM2] (X)
    LOAD    PTR              D[KM0] (W)
    ENCRYPT                           E[D[KM2] (X)] (D[KM0] (W))
    CLEAR   KR      0
    __________________________________________________________________________

                                      TABLE 5
    __________________________________________________________________________
    FUNCTION: INVERSE REENCRYPT FROM MASTER KEY, RFMX.sup.-1 (X,Y)
                    KEY      PLAIN TEXT
                                       CIPHER TEXT
    OPERATION
            OPERAND REGISTER-KR
                             REGISTER-PTR
                                       REGISTER-CTR
    __________________________________________________________________________
    LOAD    KM0 into KR
                    KM0
    GENERATE
            KM1 to KR
                    KM1
    LOAD    X into PTR       X
    DECRYPT                            D[KM1](X)
    GENERATE
    ODD PARITY
            CTR
    TRANSFER
            CTR to KR
                    D[KM1](X)
    LOAD    Z into PTR       Z
    DECRYPT                            D[D[KM1](X)](Z)
    LOAD    KM0 into KR
                    KM0
    TRANSFER
            CTR to PTR       D[D[KM1](X)](Z)
    ENCRYPT                            E[KM0](D[D[KM1](X)](Z))
    CLEAR   KR      0
    __________________________________________________________________________

                  TABLE 6
    ______________________________________
    PRIMARY   PERSONAL
    ACCOUNT   INDENTIFICATION   CARD
    NUMBER    NUMBER (ENCRYPTED)
                                SIGNATURE
    ______________________________________
    PAN 1     PIN 1             CS 1
    PAN 2     PIN 2             CS 2
    PAN 3     PIN 3             CS 3
    0         0                 0
    0         0                 0
    0         0                 0
    PAN n     PIN n             CS n
    0         0                 0
    0         0                 0
    0         0                 0
    ______________________________________

                  TABLE 7
    ______________________________________
    BANK                               COM-
    IDEN-   SITE MASTER                PUTER
    TIFICA- INTERCHANGE                IDEN-
    TION    KEY           PASSWORD     TIFICA-
    NUMBER  (ENCRYPTED)   (ENCRYPTED)  TION
    ______________________________________
    BIN 1   SMIK 1        PW 1         CID 1
    BIN 2   SMIK 2        PW 2         CID 2
    BIN 3   SMIK 3        PW 3         CID 3
    0       0             0            0
    0       0             0            0
    0       0             0            0
    BIN n   SMIK n        PW n         CID n
    0       0             0            0
    0       0             0            0
    0       0             0            0
    ______________________________________

    __________________________________________________________________________
    LIST OF ERROR HALTS
    Label            Comes
    at       Routine From
    Halt     Name    (Label) Reason
    __________________________________________________________________________
    MHLT1    MROUT   MERR1   Parameter supplied neither
                             4 or 5
    MHLT2    MROUT   MERR2   Parameter supplied neither
                             4 or 5
    MHLT3    MROUT   MERR3   Parameter supplied neither
                             4 or 5
    MWKHT1   MWKLD   MWER1   DSM Status = Busy
    MWKHT2   MWKLD   MWER2   DSM Parity Error
    MWKHT3   MWKLD   MWER3   DSM Timed Out
    EDCP4    EDCPR   EDER1   DSM Status = Busy
    EDCP5    EDCPR   EDER2   DSM Parity Error
    EDCP6    EDCPR   EDER3   DSM Timed Out
    MVE3     MOVE7   MVER1   DSM Parity Error
    MVE4     MOVE7   MVER2   DSM Timed Out
    WKL2     WKLOD   WKER2   DSM Parity Error
    WLK3     WKLOD   WKER3   DSM Timed Out
    WKL4     WKLOD   WKER1   DSM Status = Busy
    CMPR3    COMPR   CMPR2   The 2 fields being compared
                             are not equal
    DBUG4    START   DBER1   DSM Parity Error
    DBUG5    START   DBER2   DSM timed out or not ready
    __________________________________________________________________________
    NAME/LABEL
             OP CODE
                   OPERAND       COMMENTS
    __________________________________________________________________________
                   ; MAIN ROUTINE, CAN BE USED AT
                   ; TERMINAL OR AT HOST PRO-
                   ; CESSING CENTER (HPC). IF
                   ; USED AT TERMINAL, WK & TK
                   ; ARE GENERATED GIVEN SP1, TID,
                   ; AND KMT. ALL INTERMEDIATE
                   ; VALUES ARE GENERATED. WK
                   ; HAS ODD PARITY AFTER COMPLE-
                   ; TION OF THE ROUTINE. AFTER
                   ; COMPLETION, THE OPERATING
                   ; PROGRAM MUST REQUEST ENCI-
                   ; PHERMENT OF THE TRANSAC-
                   ; TION REQUEST MESSAGE USING
                   ; WK BY MAKING 2 CALLS, ONE
                   ; TO LOAD WK INTO ACTIVE REG.
                   ; & ONE TO ENCIPHER N-8 BYTE
                   ; GROUPS, APPEND TK AND TRANS
                   ; MIT THE TRANSACTION RE-
                   ; QUEST MESSAGE (TRM) TO THE
                   ; HPC. WK IS SAVED IN ORDER
                   ; TO DECIPHER RESONSE MESSAGE
                   ; RECEIVED FROM THE HPC.
                   ; REQUIRES MVI A, 5H (ENCIPH.)
                   ;
                   ; IF USED AT HOST PROCESSING
                   ; CENTER (HPC), WK & SP1 ARE
                   ; GENERATED GIVEN TK, TID &
                   ; KMT, ALL REQUIRED INTER
                   ; MEDIATE VALUES ARE GENER-
                   ; ATED. WK HAS ODD RARITY.
                   ; AFTER COMPLETION OF ROUTINE
                   ; THE OPERATING PROGRAM MUST
                   ; REQUEST DECIPHERMENT OF THE
                   ; TRM USING WK BY MAKING 2
                   ; CALLS, ONE TO LOAD WK INTO
                   ; ACTIVE REGISTER & ONE TO
                   ; DECIPHER N-8 BYTE GROUPS
                   ; VALIDATE THE PIN, ETC. IN
                   ; SP1 TO AUTHENTICATE THE
                   ; TRANSACTION, PREPARE A RE-
                   ; SPONSE, USE CALLS TO ENCI-
                   ; PHER RESPONSE USING WK, AND
                   ; TRANSMIT RESPONSE TO THE
                   ; TERMINAL. REQUIRES
                   ; MVI A, 4H (DECIPHER).
                   ; IN ADDITION, IN H & L REG.
                   ; MUST BE THE ADDRESS OF THE
                   ; FIRST OF A LIST OF 5
                   ; ADDRESSES AS FOLLOWS-
                   ; 1.
                       ADDR. OF SP1 LOCATION. IF
                   ;   AT TERMINAL OR INTO
                   ;   WHICH SP1 PLACED IF AT
                   ;   HPC
                   ; 2.
                       ADDR. OF TID LOCATION
                   ; 3.
                       ADDR. OF KMT LOCATION
                   ;   (KMT ENCIPHERED USING
                   ;   KMO IF AT HPC)
                   ; 4.
                       ADDR. OF 8-BYTE AREA
                   ;   INTO WHICH WK WILL BE
                   ;   PLACED
                   ; 5.
                       ADDR. OF 8-BYTE AREA
                   ;   INTO WHICH TK WILL BE
                   ;   PLACED IF AT TERMINAL
                   ;   OR ADDR. OF TK LOC.
                   ;   IF AT HPC.
                   ;
                   ; MVI A,5H IF TERMINAL OR
                   ; MVI A,4H IF HPC
                   ; LXI H, ADDRESS
                   ; CALL MROUT
                   ;
             NAME  SENDRO
    MROUT:   PUSH  PSW
             PUSH  B
             PUSH  D
             STA   MRPAR         ; STORE EN/DE PAR
                                 ; AMETER
             LXI   B, 2H         ; CONSTANT TO B
                                 ; FOR ADDR. MODIF-
                                 ; ICATION
             SHLD  IADSP1        ; STORE INDIR. SP1
             DAD   B             ; INCR. ADDR.
             SHLD  IADTID        ; STORE INDIR. TID
             DAD   B             ; INCR. ADDR.
             SHLD  IADKMT        ; STORE INDIR. KMT
             DAD   B             ; INCR. ADDR.
             SHLD  IADWK         ; STORE INDIR. WK
             DAD   B             ; INCR. ADDR.
             SHLD  IADTK         STORE INDIR. TK
             LDA   MRPAR         ; LOAD EN/DE PARAM.
             CPI   5H            ; COMPARE- IF TERM.
             JZ    MRT1          ; IF TERMINAL, SKIP
                                 ; DECIPHERING KMT
             CPI   4H            ; COMPARE IF HPC
    MERR1:   JNZ   MHLT1         ; JUMP TO ERROR
                                 ; HALT-NOT HPC
             MVI   A, 3H         ; PARAMETER TO LHLD
             LXI   H, KMO        ; LOAD MASTER KEY
                                 ; AS ACTIVE KEY
             CALL  MWKLD         ; CALL ROUTINE
             LHLD  IADKMT        ; INDIR. KMT ADDR
                                 ; TO H REG.
             SHLD  $ + 1         ; STORE IN INSTR.
             LHLD  OOH           ; KMT ADDR TO H
             MVI   A, 4H         ; PARAM. TO A
             LXI   D, KMT        ; LOCATION INTO
                                 ; WHICH KMT WILL
                                 ; BE PUT AFTER IT
                                 ; IS DECIPHERED
                                 ; USING KMO
             CALL  EDCPR         ; DECIPHER KMT
             LXI   H, KMT        ; KMT (DECIPHERED)
                                 ; ADDRESS TO H
             CALL  MKODD         ; MAKE ODD PARITY
    MRT1:    MVI   A,01000001B   ; VARIANT 1 PARAM
                                 ; TO A REG.
             LXI   D, KMT1       ; KMT1 ADDR TO D
             LXI   H, KMT        ; KMT ADDR TO H
             CALL  GNMKV         ; MAKE VARIANT 1
             MVI   A,00001001B   ; VARIANT 2 PARAM
             LXI   D, KMT2       ; KMT2 ADDR TO D
             LXI   H, KMT        ; KMT ADDR TO H
             CALL  GNMKV         ; MAKE VARIANT 2
             LHLD  IADKMT        ; INDIR KMT ADDR
                                 ; TO H REG
             SHLD  $ + 1         ; STORE IN INSTR.
             LHLD  OOH           ; KMT ADDR TO H
             MVI   A, 3H         ; PARAM. TO A
             CALL  MWKLD         ; LOAD KMT AS
                                 ; ACTIVE KEY
             LHLD  IADTID        ; INDIR TID ADDR
                                 ; TO H REG
             SHLD  $ + 1         ; STORE IN INSTR.
             LHLD  OOH           ; TID ADDR TO H
             LXI   D, SK         ; ADDR SK TO H
             MVI   A, 4H         ; DECIPHER PARAM
                                 ; TO A REG.
             CALL  EDCPR         ; GENERATE SK =
                                 ; D/KMT/(TID)
             LXI   H, KMT1       ; KMT1 ADDR TO A
             MVI   A, 3H         ; PARAM TO H
             CALL  MWKLD         ; LOAD KMT1 AS
                                 ; ACTIVE KEY
             MVI   A, 4H         ; DECIPH. PAR. A
             LXI   H, SK         ; SK ADDR TO H
             LXI   D, DT1SK      ; ADDR TO D
             CALL  EDCPR         ; GENERATE
                                 ; D/KMT1/(SK)
             LXI   H, DT1SK      ; ADDR TO H
             CALL  MKODD         ; MAKE ODD PARITY
             MVI   A, 3H         ; PARAM TO A
             LXI   H, KMT2       ; KMT2 ADDR TO H
             CALL  MWKLD         ; LOAD KMT2 AS
                                 ; ACTIVE KEY
             MVI   A, 4H         ; DECIPHER PARAM
                                 ; TO A REG
             LXI   H, SK         ; ADDR SK TO H
             LXI   D, DT2SK      ; ADDR TO D
             CALL  EDCPR         ; GENERATE
                                 ; D/KMT2/(SK)
             LXI   H, DT2SK      ; ADDR TO H
             CALL  MKODD         ; MAKE ODD PARITY
             LDA   MRPAR         ; LOAD EN/DE PAR.
             CPI   4H            ; COMPARE IF HPC
             JZ    MRT2          ; IF HPC, JUMP TO
                                 ;OTHER ROUTINE
             CPI   5H            ; COMPARE IF
                                 ; TERMINAL
    MERR2:   JNZ   MHLT2         ; JUMP TO ERROR
                                 ; HALT-NOT TERM.
             MVI   B, 8H         ; COUNT TO B
             LXI   D, TEMP1      ; TO ADDR TO D
             LXI   H, DT1SK      ; FROM ADDR TO H
             CALL  MOVEN         ; MOVE 8 BYTES,
             MVI   B, 8H         ; COUNT TO B
             LXI   D, TEMP2      ; TO ADDR TO D
             LXI   H, DT2SK      ; FROM ADDR TO H
             CALL  MOVEN         ; DT2SK TO TEMP2
             LHLD  IADSP1        ; INDIR SP1 ADDR
                                 ; TO H REG
             SHLD  $ + 1         ; STORE IN INSTR.
             LHLD  OOH           ; SP1 ADD TO H
             MVI   B, 8H         ; COUNT TO B
             LXI   D, TEMP3      ; TO ADDR TO D
             CALL  MOVEN         ; SP1 TO TEMP3
             JMP   MRT3          ; JUMP TO CONTINUE
                                 ; ROUTINE
                   ;
                   ; SUBROUTINE- IF HPC, SIMILAR
                   ; TO PREVIOUS ROUTINE
                   ;
    MTR2:    MVI   B, 8H         ; COUNT TO B
             LXI   D, TEMP1      ; TO ADDR TO D
             LXI   H, DT2SK      ; FROM ADDR TO H
             CALL  MOVEN         ; DT2SK TO TEMP1
             MVI   B, 8H         ; COUNT TO B



             LXI   D, TEMP2      ; TO ADDR TO D
             LXI   H, DT1SK      ; FROM ADDR TO H
             CALL  MOVEN         ; DT1SK TO TEMP2
             LHLD  IADTK         ; INDIR TK ADDR
                                 ; TO H REG.
             SHLD  $ + 1         ; STORE IN INSTR.
             LHLD  OOH           ; TK ADDR TO H
             MVI   B, 8H         ; COUNT TO B
             LXI   D, TEMP3      ; TO ADDR TO D
             CALL  MOVEN         ; TK TO TEMP3
                                 ; END OF SUBROUT.
                   ; CONTINUE REST OF PROGRAM
    MRT3:    MVI   A, 3H         ; SET KMT ACTIVE
                                 ; PARAMETER
             LXI   H, KMT        ; ADDR TO H
             CALL  MWKLD         ; CALL ROUTINE
             MVI   A, 4H         ; DECIPH. PAR. TO A
             LXI   H, TEMP3      ; DATA TO BE
                                 ; DECIPHERED
             LXI   D, TEMP4      ; ADDR OF RESULT
             CALL  EDCPR         ; GENERATE
                                 ; D/KMT/(SP1) (E)
                                 ; OR D/KMT/(TK) (D)
             MVI   A, 3H         ; SET KEY ACTIVE
                                 ; PARAMETER
             LXI   H, TEMP 1     ; ADDR TO H REG
                                 ; D/KMT1/(SK) (E)
                                 ; OR D/KMT2/(SK) (D)
             CALL  MWKLD         ; LOAD INTO ACTIVE
                                 ; REGISTER
             MVI   A, 5H         ; ENCIPHER PARAM.
                                 ; TO A REG.
             LXI   H, TEMP4      ; DATA TO BE ENC-
                                 ; IPHERED
             LXI   D, SP2        ; SP2 IF TERM.,
                                 ; SP3 IF HPC
             CALL  EDCPR         ; GENERATE SP2 OR
                                 ; SP3 (D)
             MVI   A, 3H         ; SET KEY ACTIVE
                                 ; PARAMETER
             LXI   H, KMT        ; KMT ADDR TO H
             CALL  MWKLD         ; SET KMT AS
                                 ; ACTIVE KEY
             MVI   A, 4H         ; DECIPHER PARAM.
                                 ; TO A REG.
             LXI   H, SP2        ; ADDR OF SP2 (E)
                                 ; OR SP3 (D) TO H
             LXI   D, TEMP4      ; ADDR. OF RESULT
             CALL  EDCPR         ; GENERATE EITHER
                                 ; D/KMT/(SP2) (E)
                                 ; D/KMT/(SP3) (D)
             MVI   A, 3H         ; SET KEY ACTIVE
                                 ; PARAMETER
             LXI   H, TEMP1      ; SET EITHER
                                 ; D/KMT1/(SK) (E) OR
                                 ; D/K MT2/(SK) (D)
                                 ; ACTIVE
             CALL  MWKLD         ; SET KEY ACTIVE
             MVI   A, 5H         ; ENCIPH. PARAM TO A
             LXI   H, TEMP4      ; ADDR. OF EITHER
                                 ; D/KMT/(SP2) OR
                                 ; D/KMT/(SP3)
             LXI   D, TWK        ; RESULT ADDR TO D
             CALL  EDCPR         ; GENERATE WK
             LXI   H, TWK        ; WK ADDR TO H
             CALL  MKODD         ; MAKE WK ODD PARITY
             MVI   A, 3H         ; SET KEY ACTIVE
                                 ; PARAMETER
             LXI   H, TEMP2      ; SET ACTIVE EITHER
                                 ; D/KMT2/(SK) (E)
                                 ; D/KMT1/(SK) (D)
             CALL  MWKLD         ; SET KEY ACTIVE
             MVI   A, 4H         ; DECIPH PAR. TO A
             LXI   H, TWK        ; WK ADDR TO H
             LXI   D, TEMP4      ; RESULT ADDR TO D
             CALL  EDCPR         ; GENERATE EITHER
                                 ; D/D/KMT2/(SK)/
                                 ; (WK) OR
                                 ; D/D/KMT1/(SK)/
                                 ; (WK)
             LXI   H, KMT        ; KMT ADDRESS TO H
             MVI   A, 3H         ; SET KEY ACTIVE
                                 ; PARAMETER
             CALL  MWKLD         ; SET KMT ACTIVE
             MVI   A, 5H         ; ENCIPH PAR. TO A
             LXI   H, TEMP4      ; ADDR. OF EITHER
                                 ; D/D/KMT2/(SK)/
                                 ; (WK) OR
                                 ; D/D/KMT1/(SK)
                                 ; (WK)
             LXI   D, SP3        ; RESULT ADDR TO D
             CALL  EDCPR         ; GENERATE SP3 (E)
                                 ; OR SP2 (D)
             MVI   A, 3H         ; SET ACTIVE PAR TO A
             LXI   H, TEMP2      ; ADDR OR EITHER
                                 ; D/KMT2/(SK) (E) OR
                                 ; D/KMT1/(SK) (D)
             CALL  MWKLD         ; SET KEY ACTIVE
             MVI   A, 4H         ; DECIPH PARAM TO A
             LXI   H, SP3        ; ADDRESS OF EITHER
                                 ; SP3 (E) OR SP2 (D)
             LXI   D, TEMP4      ; RESLT ADDR TO D
             CALL  EDCPR         ; GENERATE EITHER
                                 ; D/D/KMT2/(SK)/(SP3)
                                 ; D/D/KMT1/(SK)/(SP2)
             MVI   A, 3H         ; SET KEY ACTIVE PAR.
             LXI   H, KMT        ; KMT ADDR TO H
             CALL  MWKLD         ; SET KMT ACTIVE
             MVI   A, 5H         ; ENCIPH PAR TO A
             LXI   H, TEMP4      ; ADDR OF EITHER
                                 ; D/D/KMT2/(SK)/(SP3)
                                 ; D/D/KMT1/(SK)/(SP2)
             LXI   D, TTK        ; RESULT ADDR TO D
             CALL  EDCPR         ; GENERATE EITHER
                                 ; TK OR SP1
             LHLD  IADWK         ; INDIR WK ADDR H
             SHLD  $ +  1        ; STORE IN INSTR.
             LHLD  OOH           ; DIRECT WK ADDR H
             XCHG                ; MOVE H TO D
             LXI   H, TWK        ; WK ADDR TO H
             MVI   B, 8H         ; COUNT TO B
             CALL  MOVEN         ; MOVE WK
             LDA   MRPAR         ; EN/DE PARAM TO A
             CPI   4H            ; COMPARE IF HPC
             JZ    MRT4          ; IF HPC, JUMP TO
                                 ; OTHER ROUTINE
             CPI   5H            ; COMPARE IF TERM
    MERR3:   JNZ   MHLT3         ; JUMP TO ERROR
                                 ; HALT NOT TERM.
             LHLD  IADTK         ; INDIR TK ADDR H
             SHLD  $ + 1         ; STORE IN INSTR
             LHLD  OOH           ; DIR. TK ADDR H
             XCHG                ; MOVE H TO D
             LXI   H, TTK        ; ADD OF TK TO H
             MVI   B, 8H         ; COUNT TO B
             CALL  MOVEN         ; MOVE TK TO DTK
             JMP   MRT5          ; JUMP TO CONT.
                   ; IF HPC, TRANSFER SP1
                   ;
    MRT4:    LHLD  IADSP1        ; INDIR SP1 ADDR
                                 ; TO H
             SHLD  $ + 1         ; STORE IN INSTR.
             LHLD  OOH           ; DIR. SP1 ADR. H
             XCHG                ; MOVE H TO D
             LXI   H, TTK        ; ADDR OF SP1 TO
                                 ; H REG.
             MVI   B, 8H         ; COUNT TO B
             CALL  MOVEN         ; MOVE SP1
    MRT5:    POP   D
             POP   B
             POP   PSW
             RET                 ; RETURN
    MHLT1:   HLT                 ; FROM MERR1, NOT
                                 ; 4 OR 5, NOT
                                 ; TERMINAL OR HPC
    MHLT2:   HLT                 ; FROM MERR2 NOT
                                 ; 4 OR 5, NOT HPC
                                 ; OR TERMINAL
    MHLT3:   HLT                 ; FROM MERR3, NOT
                                 ; HPC OR TERM,
                                 ; NOT 4 OR 5
                   ; MASTER OR WORKING KEY LOAD
                   ; ROUTINE NO DECIPHER
                   ; CALLING SEQUENCE
                   ; MVI A, PARAMETER
                   ; LXI H, MASKAD MASTER KEY
                   ; CALL MWKLD ADDRESS OR
                   ;   WORKING KEY
                   ;   ADDRESS
                   ; PARAM
                         = 2H FOR MASTER KEY
                   ;     =  3H FOR WORKING KEY
                   ;      TO BE ACTIVE KEY
                   ;
    MWKLD:   PUSH  PSW
             PUSH  B
             PUSH  D
             MVI   B,OH          ; CLEAR B REG
             MOV   C, A          ; MOVE PARAM TO C
             XCHG                ; EXCHANGE D, H
             LHLD  BPARAM        ; LOAD BPARAM IN H
             DAD   B             ; ADD PARAM TO H
             SHLD  MWK2 + 1      ; STORE RESULT IN
                                 ; INSTRUCTION
             XCHG                ; RESTORE H & L
             IN    BPARAM + REDST
                                 ; READ STATUS
             ORA   A             ; SET FLAGS
    MWER1:   JNZ   MWKHT1        ; GO TO HALT
             MVI   B, 8          ; COUNT TO B REG
    MWK1:    MOV   A, M          ; LOAD NTH CHAR
    MWK2:    OUT   OH            ; OUTPUT NTH CHAR
             INX   H             ; INCR. FROM ADDR
             DCR   B             ; DECR. COUNT
             JNZ   MWK1          ; LOOP
             MVI   A, 50         ; COUNT 50 TO A
    MWK3:    DCR   A             ; DECR. A REG
             JNZ   MWK3          ; LOOP-PROG DELAY
             IN    BPARAM + REDST
                                 ; CHECK STATUS
             ORA   A             ; SET FLAGS
    MWER2:   JM    MWKHT2        ; PARITY ERROR HLT
    MWER3:   JNZ   MWKHT3        ; TIME OUT HALT
             POP   D             ; END ROUTINE
             POP   B             ; HOUSEKEEPING
             POP   PSW           ;
             RET                 ; RETURN
    MWKHT1:  HLT                 ; BUSY HALT
    MWKHT2:  HLT                 ; PARITY ERROR HLT
    MWKHT3:  HLT                 ; TIME OUT HALT
                   ; ROUTINE TO ENCIPHER OR
                   ; DECIPHER N GROUPS OF 8
                   ; BYTES, N NO MORE THAN 254D.
                   ; ANY NUMBER OF BYTES THAT
                   ; ARE AN INTEGRAL MULTIPLE OF
                   ; 8 BYTES MAY BE PROCESSED
                   ; TO A MAXIMUM OF 2032D.
                   ; PARAMETER IN A REG
                   ;  = 5H FOR ENCIPHER
                   ;  = 4H FOR DECIPHER
                   ; B REG = NUMBER OF 8 BYTE GROUPS
                   ; D & E REG. CONTAINS ADDRESS
                   ; OF RESULTS
                   ; H & L REG. CONTAINS ADDRESS
                   ; OF DATA TO BE ENCIPHERED
                   ; OR DECIPHERED
                   ; IF ENCIPHER, H = PLAIN TEXT
                   ; IF DECIPHER, H = CIPHER TEXT
                   ; MVI A, PARAMETER
                   ; MVI B, N
                   ; LXI H, FROM
                   ; LXI D, TO
                   ; CALL NGEDR
    NGEDR:   PUSH  PSW
             STA   NGPAR         ; STORE PARAM
             MOV   A, B          ; N TRANSF. TO A
             STA   NGRPS         ; STORE N
             SHLD  NFROM         ; STORE FROM ADD.
             XCHG                ;
             SHLD  NTOAD         ; STORE TO ADD.



             XCHG                ; RESTORE
             ADI   OOH           ; SET FLAGS
             JZ    NGOUT         ; N = 0, COMPLETE
             LDA   NGPAR         ; LOAD PARAM, A
    NGD1:    CALL  EDCPR         ; CALL 8 BYTE EN/
                                 ; DE/CIPHER ROUT.
             LDA   NGRPS         ; N TO A REG
             DCR   A             ; DECR. N
             STA   NGRPS         ; STORE N - 1
             JZ    NGOUT         ; IF ZERO, DONE
             LHLD  NTOAD         ; TO ADR. TO H
             LXI   B, 0008H      ; LOAD NO. 8, B & C
             DAD   B             ; ADD 8 TO `TO`
                                 ; ADDRESS
             SHLD  NTOAD         ; STORE MODIFIED
                                 ; ADDRESS
             XCHG                ; SWITCH `TO`
                                 ; ADDRESS TO D REG
             LHLD  NFROM         ; FROM ADR. TO H
             DAD   B             ; ADD 8 TO `FROM`
             SHLD  NFROM         ; STORE MODIFIED
                                 ; ADDRESS
             LDA   NGPAR         ; PARAM. TO A REG
             JMP   NGD1          ; JUMP TO CALL
    NGOUT:   POP   PSW
             RET                 ; RETURN
                   ; ROUTINE TO ENCIPHER OR
                   ; DECIPHER 8 BYTES, THE
                   ; WORKING KEY MUST HAVE
                   ; PREVIOUSLY BEEN LOADED INTO
                   ; THE ACTIVE KEY REGISTER.
                   ; ADDRESS OF BYTES TO BE
                   ; EN- OR DECIPHERED IN H & L
                   ; REGISTER, ADDRESS IN WHICH
                   ; TO PLACE RESULT IN D & E REG.
                   ; PARAMETER IN A REG,
                   ; ENCIPHER = 5H
                   ; DECIPHER = 4H
                   ; HAS PRGRAMMED DELAY > 320
                   ; MICROSEC. USES MOVE7
                   ; MVI A, PARAMETER
                   ; LXI H, ADDR, DATA TO BE EN-
                   ; OR DECIPHERED
                   ; LXI D, ADDR, RESULTING 8 BYTE
                   ; CALL EDCPR
                   ;
    EDCPR:   PUSH  PSW
             PUSH  B
             MVI   B, OOH        ; CLEAR B REG
             MOV   C, A          ; MOVE PARAM TO C
             SHLD  TEMP2         ; STORE H TEMPO-
                                 ; RARILY
             LHLD  BPARAM        ; LOAD BPARAM IN
                                 ; H REG.
             DAD   B             ; ADD PARAM = 4H OR
                                 ; 5H TO BPARAM
             SHLD  EDCP1 + 1     ; STORE RESULT IN
                                 ; OUT INSTRUCT.
             LHLD  TEMP2         ; RESTORE H REG.
             IN    BPARAM + REDST
                                 ; READ STATUS
             ORA   A             ; SET FLAGS
    EDER1:   JNZ   EDCP4         ; GO TO HALT
             CALL  MOVE 7        ; FIRST 7 BYTES
                                 ; TRANSMITTED OUT
    EDCP1:   OUT   OOH           ; 8th BYTE OUT
             LXI   B, 500        ; COUNT TO B REG.
    EDCP2:   CALL  DELAY         ; PROGRAMMED DELAY
             NOP                 ; > 320 MICROSEC
             IN    BPRAM + REDST ; READ STATUS
             ORA   A             ; SET FLAGS
    EDER2:   JM    EDCP5         ; GO TO PARITY HLT
    EDER3:   JNZ   EDCP6         ; GO TO TIME OUT
             MVI   B, 8H         ; COUNTER TO B
    EDCP3:   IN    BPARAM + RDDAT
                                 ; READ NTH BYTE
             STAX  D             ; STORE NTH BYTE
             INX   D             ; INCR. ADDR
             DCR   B             ; DECR. COUNT
             JNZ   EDCP3         ; LOOP
             POP   B
             POP   PSW
             RET                 ; RETURN
    EDCP4:   HLT                 ; BUSY HALT
    EDCP5:   HLT                 ; PARITY HALT
    EDCP6:   HLT                 ; TIME OUT HALT
                   ; MOVE7 SUBROUTINE TO MOVE
                   ; FIRST 7 BYTES, USED BY LOAD
                   ; WORKING KEY ROUTINE AND OTHER
                   ; REQUIRES LEFT MOST ADDRESS
                   ; IN H & L REGISTER, LXI H, ADR
                   ; CALL MOVE 7
    MOVE7:   PUSH  PSW
             PUSH  B
             MVI   B, 7          ; COUNT TO B REG
    MVE1:    MOV   A, M          ; NTH BYTE TO A
             OUT   BPARAM + WRTDAT
                                 ; WRITE NTH BYTE
             INX   H             ; INCR FROM ADDR
             DCR   B             ; DECR. COUNT
             JNZ   MVE1          ; LOOP
             MV1   A, 50         ; PROGRAMMED
    MVE2:    DCR   A             ;
             JNZ   MVE2          ; DELAY
             IN    BPARAM + REDST
                                 ; CHECK STATUS
             ORA   A             ; SET FLAGS
    MVER1:   JM    MVE3          ; PARITY ERROR HL
    MVER2:   JNZ   MVE4          ; TIME OUT HALT
             MOV   A, M          ; MOVE 8TH CHAR TO
                                 ; A REG FOR FINAL
                                 ; WRITE
             POP   B
             POP   PSW
             RET                 ; RETURN
    MVE3:    HLT                 ; PARITY HALT
    MVE4:    HLT                 ; TIME OUT HALT
                                 ;
                   ; MAKE ODD PARITY, 8 BYTES,
                   ; ADDRESS IN H & L
                   ; LXI H, ADDR
                   ; CALL MKODD
    MKODD:   PUSH  PSW
             PUSH  B
             MVI   B, 8H         ; COUNT B
    MKD2:    MOV   A, M          ; LOAD NTH BYTE
             ADI   OOH           ; SET PARITY FLAG
             JPO   MKD1          ; IF PARITY IS
                                 ; ODD, SKIP 2 INST-
                                 ; RUCTIONS
             XRI   00000001B     ; MAKE RITE MOST
                                 ; BIT ODD PARITY
             MOV   M, A          ; STORE NTH BYTE
    MKD1:    INX   H             ; INCR ADDRESS
             DCR   B             ; DECR. COUNT
             JNZ   MKD2          ; LOOP
             POP   B
             POP   PSW
             RET                 ; RETURN
                   ; ROUTINE TO GENERATE MASTER
                   ; KEY VARIANTS V1 OR V2 FROM
                   ; MASTER KEY
                   ; A REG CONTAINS PARAMETER TO
                   ; SPECIFY WHICH VARIANT
                   ; V1 = 01000001B
                   ; V2 = 00001001B
                   ; D & E CONTAINS ADDR OF VARIANT
                   ; H & L ADDRESS OF MASTER KEY
                   ; MVI A, PARAMETER
                   ; LXI D, VARIANT (LOCATION)
                   ; LXI H, MASTER KEY (LOCATION)
                   ; CALL GNMKV
    GNMKV:   PUSH  PSW
             PUSH  B
             STA   GKV2 + 1      ; STORE PARAMETER
                                 ; IN INSTRUCTION
             MVI   B, 8H         ; COUNT TO B REG
    GKV1:    MOV   A, M          ; LOAD NTH BYTE
    GKV2:    XRI   OOH           ; MAKE VARIANT X,
                                 ; X = 1 OR 2
             STAX  D             ; STORE NTH BYTE
             INX   H             ; INCR. FROM ADR.
             INX   D             ; INCR. TO ADDR.
             DCR   B             ; DECR. COUNT
             JNZ   GKV1          ;LOOP
             POP   B             ;
             POP   PSW           ;
             RET                 ; RETURN
                   ; WORKING KEY LOAD ROUTINE
                   ; KEY DECIPHERED USING MASTER
                   ; KEY WHICH MUST BE PREVIOUSLY
                   ; LOADED IN MASTER KEY REG.
                   ; WORKING KEY LOADED INTO ACT.
                   ; REGISTER AFTER DECIPHERING
                   ; USES MOVE7
                   ; LXI H, ADDR ADDRESS OF KEY
                   ; CALL WKLOD
    WKLOD:   PUSH  PSW
             IN    BPARAM + REDST
                                 ; CHECK STATUS
             ORA   A             ; SET FLAGS
    WKER1:   JNZ   WKL4          ; GO TO HALT
             CALL  MOVE7         ; MOVE FIRST 7 BTE
             OUT   BPARAM + DECWK
                                 ; 8TH BYTE OUT
             LXI   B, 500        ; PROGRAMMED
    WKL1:    CALL  DELAY         ; DELAY
             NOP                 ; > 320 MICROSEC.
             IN    BPARAM + REDST
                                 ; CHECK STATUS
             ORA   A             ; SET FLAGS
    WHER2:   JM    WKL2          ; PARITY ERR. HALT
    WKWE3:   JNZ   WKL3          ; TIME OUT HALT
             POP   PSW           ;
             RET                 ; RETURN
    WKL2:    HLT                 ; PARITY ERR. HLT
    WKL3:    HLT                 ; TIME OUT HALT
    WKL4:    HLT                 ; BUSY HALT
                   ; ROUTINE FOR PROGRAMMED
                   ; DELAYS OF MORE THAN 255D
                   ; INSTRUCTION EXECUTION
                   ; TIMES SINCE A REG IS
                   ; ONLY 8 BITS
                   ; LXI B, COUNT > 255D
                   ; CALL DELAY
    DELAY:   PUSH  PSW
             MOV   A, C          ; TRANSFER THE
             ADI   OOH           ; PART OF COUNT
             JZ    DLY2          ; LESS THAN
                                 ; 255D TO A RG
    DLY1:    DCR   A             ; DECR. A REG
             JNZ   DLY1          ; < 255D LOOP
    DLY2:    MV1   A, 254D       ; SET UP 255 LOOP
    DLY3:    DCR   A             ; DECR. A
             JNZ   DLY3          ; 255D LOOP - DCR B ; DECR. 255 LOOP
                                 ; COUNT
             JNZ   DLY2          ; LOOP ANOTHER
                                 ; 255 TIMES
             POP   PSW
             RET                 ; RETURN
                   ; ROUTINE TO MOVE N BYTES
                   ; B REG = NO. OF BYTES
                   ; D&E = TO ADDRESS
                   ; H&L = FROM ADDRESS
                   ; MAXIMUM 256 BYTES
                   ; MVI B, NO.
                   ; LXI D, TO
                   ; LXI H, FROM
                   ; CALL MOVEN
    MOVEN:   PUSH  PSW
    MVN1:    MOV   A, M          ; LOAD NTH BYTE
             STAX  D             ; STORE NTH BYTE
             INX   D             ; INCR. TO ADDR.
             INX   H             ; INCR. FROM ADDR.
             DCR   B             ; DECR. COUNT
             JNZ   MVN1          ; LOOP
             POP   PSW           ;



             RET                 ; RETURN
                   ; COMPARE 2 FIELDS SUBROUTINE
                   ; USED ONLY FOR DEBUGGING
                   ; NO. OF BYTES IN B REG.,
                   ; ADDRESS OF ONE FIELD IN H,
                   ; OTHER ADDRESS IN D
                   ; MVI B, N
                   ; LXI H, ADDR1
                   ; LXI D, ADDR2
                   ; CALL COMPR
                   ; IF FIELDS ARE NOT EQUAL,
                   ; ERROR HALT
    COMPR:   PUSH  PSW
    CMPR1:   LDAX  D             ; ONE BYTE TO A
             CMP   M             ; COMPARE ONE BYTE
    CMPR2:   JNZ   CMPR3         ; IF NOT ZERO, HLT
             INX   D             ; INCR. D REG.
             INX   H             ; INCR. H REG.
             DCR   B             ; DECR. COUNT
             JNZ   CMPR1         ; LOOP
             POP   PSW
             RET                 ; RETURN
    CMPR3:   HLT                 ; FROM CMPR2, HALT,
                                 ; 2 FIELDS NOT
                                 ; EQUAL
                   ; ROUTINE TO DEBUG ALL OF
                   ; OTHER ROUTINES, SIMULATES
                   ; TERMINAL AND HPC. SENDS
                   ; AND RECEIVES ONE MESSAGE
                   ; AFTER GENERATING WK AND
                   ; EITHER TK OR SP1. FINAL
                   ; HALT AFTER TEST IS AT FINIS
                   ; ERROR HALTS OTHERWISE.
                   ; ROUTINE IS INITIATED AT
                   ; `START` AND RUNS TO END.
                   ; USES SUBROUTINE COMPR TO
                   ; COMPARE RESULTS. ON NOT
                   ; COMPARE, ERROR HALT AT CMPR3.
    START:   STKLN 200D          ; SET STACK = 200
             LXI   SP, STACK     ; INITIALIZE STACK
             NOP
             NOP
             NOP
             NOP
             OUT   BPARAM + RESET
                                 ; INITIALIZE DSM
             MVI   A, 50         ; COUNT TO A REG.
    DBUG1:   DCR   A             ; DECR. A
             JNZ   DBUG1         ; LOOP - PROGRAMMED
                                 ; DELAY
             IN    BPARAM + REDST
                                 ; READ STATUS
             ORA   A             ; SET FLAGS
    DBER1:   JM    DBUG4         ; PARITY ERROR
    DBER2    JNZ   DBUG5         ; TIME OUT OR NOT
                                 ; READY ERROR
             MVI   A, 5H         ; PARAM = TERMINAL
             LXI   H, ADRSP1     ; ADDR. OF FIRST OF
                                 ; 5 ADDRESS LIST
                                 ; TO H
             CALL  MROUT         ; DEBUG MAIN ROUT
                                 ; GENERATE WK &
                                 ; TK USING SP1
                                 ; KMT, & TID
             MVI   A, 3H         ; PARAM = WORK KEY
                                 ; ACTIVE
             LXI   H, DWK        ; ADDR GENERATED
                                 ; WK
             CALL  MWKLD         ; SET WK ACTIVE
             MVI   A, 5H         ; PARAM = ENCIPH.
             MVI   B, 4H         ; ENCIPH. 4 EIGHT
                                 ; BYTE GROUPS
             LXI   H, TMMSG      ; ADDR. PLAIN TEXT
                                 ; TRANS. REQ. MSG.
             LXI   D, TMEMSG     ; SPACE FOR ENCIPH
                                 ; TRANS. REQ. MSG.
             CALL  NGEDR         ; ENCIPH TRM
                   ;             ; USING WK
                   ; FIRST PART OF ROUTINE AS IF
                   ; FROM TERMINAL COMPLETE,
                   ; CONTINUE TO HPC ROUTINE
                   ;
             JMP   DEBUG2        ; CONTINUE
    DBUG2:   MVI   A, 4H         ; PARAM = HPC
             LXI   H, HADSP1     ; ADDR. OF FIRST
                                 ; OF 5 ADDRESS
                                 ; LIST TO H
             CALL  MROUT         ; DEBUG REST OF
                                 ; MAIN ROUTINE
                                 ; GENER. WK & SP1
                                 ; USING TK, KMT, TID
             MVI   B, 8H         ; PARAM = LENGTH OF
                                 ; WK
             LXI   H, HPCWK      ; ADDR FIELD1
             LXI   D, DWK        ; ADDR FIELD2
             CALL  COMPR         ; COMPARE BOTH
                                 ; WK'S. HALT IF
                                 ; UNEQUAL.
             MVI   B, 8H         ; LENGTH OF SP1
             LXI   H, DSP1       ; ADDR FIELD 1
             LXI   D, HPSP1      ; ADDR FIELD 2
             CALL  COMPR         ; COMPARE BOTH
                                 ; SP1'S.
             MVI   A, 3H         ; PARAM = WORK KEY
                                 ; ACTIVE
             LXI   H, HPCWK      ; ADDR WK TO H
             CALL  MWKLD         ; SET WK ACTIVE
             MVI   A, 4H         ; PARAM = DECIPH.
             MVI   B, 4H         ; DECIPH. 4 EIGHT
                                 ; BYTE GROUPS
             LXI   H, TMEMSG     ; CIPHER TRANS.
                                 ; REQ. MSG.
             LXI   D, HPTRM      ; SPACE FOR PLAIN
                                 ; TEXT TRANS. REQ
                                 ; MSG.
             CALL  NGEDR         ; DECIPHER TRM
             MVI   B, 32         ; COUNT
             LXI   H, HPTRM      ; ADDR. FIELD 1
             LXI   D, TMMSG      ; ADDR FIELD 2
             CALL  COMPR         ; COMPARE TRM
                                 ; FROM TERMINAL
                                 ; AND FROM HPC.
                                 ; HALT ON ERROR
             MVI   A, 5H         ; PARAM = ENCIPH.
             MVI   B, 3H         ; ENCIPH. 3 EIGHT
                                 ; BYTE GROUPS
             LXI   H, HRESP      ; ADDR PLAIN TEXT
                                 ; RESPONSE MSG.
             LXI   D, HENCR      ; ADDR. LOCATION
                                 ; OF CIPHER
                                 ; RESPONSE MSG.
             CALL  NGEDR         ; ENCIPH. RESPONSE
                                 ; MSG.
                   ;
                   ; END OF HPC DEBUG, CONTINUE
                   ; TO FINAL TERMINAL DEBUG
                   ;
             JMP   DBUG3         ; CONTINUE
    DBUG3:   MVI   A, 3H         ; PARAM = WORK KEY
                                 ; ACTIVE
             LXI   H, DWK        ; ADDR WK
             CALL  MWKLD         ; SET WK ACTIVE
             MVI   A, 4H         ; PARAM = DECIPH
             MVI   B, 3H         ; DECIPH. 3 EIGHT
                                 ; BYTE GROUPS
             LXI   H, HENCR      ; CIPHER RESPONSE
             LXI   D, DTMMS      ; SPACE FOR PLAIN
                                 ; TEXT RESPONSE
             CALL  NGEDR         ; DECIPHER RESP.
             MVI   B, 24         ; PARAM = RESPONSE
                                 ; MSG. LENGTH
             LXI   H, DTMMS      ; ADDR. FIELD 1
             LXI   D, HRESP      ; ADDR. FIELD 2
             CALL  COMPR         ; COMPARE 2 RES-
                                 ; PONSE MSGS.
    FINIS:   HLT                 ; END OF ROUTINE
                                 ; DEBUG COMPLETE
    DBUG4:   HLT                 ; PARITY ERROR
                                 ; HALT, FROM DBER1
    DBUG5:   HLT                 ; TIME OUT OR NOT
                                 ; READY HALT,
                                 ; FROM DBER2.
             END   START         ; END, TO START.
                   ; PARAMETERS, LISTS, CONSTANTS
                   ;
                   ;
                   ;
    BPARAM   EQU   100H          ; DSM BEGIN PARAM.
    MKEYL    EQU   2H            ; MASTER KEY LOAD
    WKEYL    EQU   3H            ; WORKING KEY LOAD
    DECDT    EQU   4H            ; DECIPHER DATA
    ENCDT    EQU   5H            ; ENCIPHER DATA
    DECWK    EQU   6H            ; DECIPHER WORK. KEY
    ENCWK    EQU   7H            ; ENCIPHER WORK. KEY
    RESET    EQU   1H            ; RESET DSM
    REDST    EQU   2H            ; READ STATUS
    TRMAK    EQU   1H            ; TRANSFER MAJOR KEY
    RDDAT    EQU   4H            ; READ DATA
    WRTDAT   EQU   0H            ; WRITE DATA
    WS1:     DS    10            ; WORK STORE ADDR. LIST
    IADSP1   EQU   WS1           ; INDIR. ADDR. SP1
    IADTID   EQU   WS1 + 2       ; INDIR. ADDR TID
    IADKMT   EQU   WS1 + 4       ; INDIR ADDR KMT
    IADWK    EQU   WS1 + 6       ; INDIR ADDR WK
    IADTK    EQU   WS1 + 8       ; INDIR ADDR TK
    WS2:     DS    120           ; WORK STORE
    SPARE    EQU   WS2           ; SPARE LOCATION
    KMT1     EQU   WS2 + 8       ; KMT1 LOCATION
    KMT2     EQU   WS2 + 16      ; KMT2 LOCATION
    TWK      EQU   WS2 + 24      ; TEMP WK
    TTK      EQU   WS2 + 32      ; TEMP TK
    SK       EQU   WS2 + 40      ; SK LOCATION
    DT1SK    EQU   WS2 + 48      ; D/KMT1/(SK)
    DT2SK    EQU   WS2 + 56      ; D/KMT2/(SK)
    SP2      EQU   WS2 + 64      ; SP2 LOCATION
    SP3      EQU   WS2 + 72      ; SP3 LOCATION
    TEMP1    EQU   WS2 + 80      ; TEMP LOCATION
    TEMP2    EQU   WS2 + 88      ; TEMP LOCATION
    TEMP3    EQU   WS2 + 96      ; TEMP LOC.
    TEMP4    EQU   WS2 + 104     ; TEMP LOC.
    MRPAR    EQU   WS2 + 112     ; TEMP EN/DE PAR
    KMT:     DB    1301H         ; DUMMY KMT, BEFORE
             DB    1301H         ; DEBUGGING, MUST
             DB    1301H         ; BE MADE EQUAL TO
             DB    1301H         ; D/KMO/(EKMT)
                                 ; THIS VALUE IS
                                 ; USED FOR DEBUG.
                                 ; AS IF FROM TERM.
    WS3:     DS    6             ; WORK STORE
    NGPAR    EQU   WS3           ; STORE EN/DE/
                                 ; CIPHER PARAMET.
    NGRPS    EQU   WS3 + 1       ; STORE N GROUPS
    NFROM    EQU   WS3 + 2       ; STORE FROM ADR.
    NTOAD    EQU   WS3 + 4       ; STORE TO ADDR.
             ; FOR DEBUGGING     ONLY
             ;
    KMO:     DB    EFEFH         ; DUMMY
             DB    EFEFH         ; MASTER
             DB    EFEFH         ; KEY
             DB    EFEFH         ;
    EKMT:    DB    EOEOH         ; DUMMY
             DB    EOEOH         ; ENCRYPTED
             DB    EOEOH         ; TERMINAL
             DB    EOEOH         ; KEY
    DTID:    DB    0101H         ; DUMMY
             DB    0101H         ;
             DB    0101H         ; TID
             DB    0101H         ;



    DWS:     DS    16            ; DEBUG LOCATIONS
    DWK      EQU   DWS           ; DUMMY W:K LOC
    DTK      EQU   DWS + 8       ; DUMMY TK LOC
    DSP1:    DB    1010H         ; DUMMY
             DB    1010H         ; SP1
             DB    1010H         ; PARAMETER
             DB    1010H         ;
    ADRSP1:  DW    DSP1          ; ADDR OF SP1
    ADRTID:  DW    DTID          ; ADDR OF TID
    ADRKMT:  DW    KMT           ; ADDR OF KMT
    ADRWK:   DW    DWK           ; ADDR OF WK
    ADRTK:   DW    DTK           ; ADDR OF TK
                                 ; THE ABOVE LIST IS
                                 ; USED FOR TERMIN.
                                 ; DEBUGGING
    TMMSG:   DB    `IMPORTAN`    ; TRANSACTION REQ.
             DB    `T MESSAG`    ; MSG. USED AT
             DB    `E to FOL`    ; TERM., WILL BE
             DB    `LOW SOON`    ; ENCIPH. BY WK
    DTMMS:   DB    24            ; AREA FOR ENCIPH.
                                 ; TRANS. REQ. MSG.
                                 ; RESPONSE FROM
                                 ; HPC AFTER DECIPH.
    HPCWK:   DS    8             ; AREA IN WHICH TO
                                 ; STORE WK GENERATED
                                 ; AT DUMMY HPC,
                                 ; CHECK AGAINST DWK
    HPSP1:   DS    8             ; AREA FOR SP1
                                 ; FROM DUMMY HPC
                                 ; CHECK AGAINST DSP1
    HPTRM:   DS    32            ; AREA FOR DECIPH
                                 ; TRANS. REQ. MSG.
                                 ; FROM HPC, CHECK
                                 ; AGAINST TMMSG
    HRESP:   DB    `DISREGAR`    ; RESPONSE MSG.,
             DB    `D FIRST`     ; WILL BE ENCIPH.
             DB    `MESSAGEX`    ; BY HPC USING WK
    HENCR:   DS    24            ; AREA FOR ENCIPH
                                 ; RESPONSE MSG.,
                                 ; USED AT HPC
    HADSP1:  DW    HPSP1         ; SP1 LOCATION
    HADTID:  DW    DTID          ; TID LOC.
    HADKMT:  DW    EKMT          ; ENCIPH. KMT LOC.
    HADWK:   DW    HPCWK         ; HPC-WK LOC.
    HADTK:   DW    DTK           ; TK LOC.
    TMEMSG:  DS    32            ; AREA FOR ENCRYP-
                                 ; TED TRANS. REQ.
                                 ; MSG. FROM TERM.
    __________________________________________________________________________

• Inventors
  Sendrow, Marvin;
• Published
  Mar-2-1982
• Current US Classes:
  235/379
  235/382
  380/281
  380/45
  705/43
  705/71
  705/72
  713/185
  902/2
  902/5
• Application #
  129110
• International Classes
  H04L 009/00
• Field of Search
  178/22 178/22.08 178/22.09 375/2 235/379 235/380 235/382 340/149
• Examiner
  Birmiel; Howard A.
• Agent
  Whitham; C. Lamont, Ferguson, Jr.; Gerald J., Baker; Joseph J.
• US Patent References:
  3956615
  3985998
  4025760
  4123747
  4214230
  4223403
  4238854
  4259720