Method for controlling access to information6516315Abstract A method for controlling access to information, which includes a plurality of data objects, on a computer system being accessible to a plurality of users is provided which generally comprises providing an access right for each relationship between a user and a data object, wherein each user can have a plurality of relationships to each data object, determining each relationship between the user and the data object when a user requests information about a data object, determining the security classification for each relationship between the user and the data object, and then granting the user access to the data object if one of the security classifications for all the relationships is equal to or greater than the security classification of the data object, and denying the user access to the data object if the security classifications for all the relationships is less than the security classification of the data object. Claims What is claimed is: Description FIELD OF THE INVENTION
TABLE 1
Object Oriented Terms, Equivalent Terms and Definitions.
Term Used Equivalent Terms Definition
Object Concept A generic concept representing
an abstract information item
Package Database, Domain A collection of objects, esp.
classes and sub-packages
Class Table, Type A prototype for objects
Super Class The class from which a given
class is inherited
Sub Class The classes that inherit from a
given class
Attribute Column, Property, A property defined for a class
Field
Instance Row, Record, Tuple A single object
Attribute Cell, Value A property value for an instance
Value
Folder Aggregate An object and its sub-objects
Relationship Associations, Foreign An association definition between
Definition Key classes
Relationship Join, Link An association between two
instances
The system consists of objects at multiple levels of granularity, ranging from a set of databases to a single value in a record. Objects belong to Classes. For example, patient John Doe object belongs to the patient class. Relationship classes link object classes. For example, the patient-physician class links the physician class and the patient class. Objects may have relationships with other objects. For example, patients can have relationships with physicians. Each relationship belongs to a relationship class. Each relationship is preferably a link between two objects. A relationship class may define the formation of a folder. For example, as shown in FIG. 1, the relationship between a patient object 27 and a patient employment object 29 can be a vertical parent/child relationship that makes patient employment part of the patient folder. Thus, an object may consist of a number of sub-objects, forming a folder. A patient's folder may consist of many other objects having subjects such as patient bio-data, insurance, financial, problems, encounters and treatment records. An object at any level of granularity may be marked with a security classification that determines its accessibility and sensitivity level. For example, patient bio-data, family and employment records have a security classification label PatientBio 27. Optionally, the security classification of data objects may be derived using security rules. For example, the security classification of patient clinical records may be derived from the type of diagnosis performed. Subjects are the users of the system who perform functions on objects. For example, physicians are a type of subject. Subjects can only gain access to objects by having relationships to objects. Each relationship provides access to the object's folder. For example, a physician may have a relationship 14 to a patient that defines the role 32 of the physician as the patient's "primary care provider," and thereby the physician has access to the patient's folder. Each relationship 14 defines a role 34 that the subject is performing for the object. Each such role is defined with access rights 21 to items in the folder. Each access right specifies at least what security classification the object has and also can define what functions may be performed on objects of a given security classification in the folder. For example, a "Primary Care Provider" may have read-only access to PatientBio information, but full access to PatientClinical information. Optionally, subject/object relationships may also define context security rules that determine access based on the context of the relationship. For example, the physician-patient relationship may store the starting date 30 and ending date 28 of the relationship 14, which may be used to deny access before the starting date and after the ending date. With the present invention, when a subject tries to perform a function on parts of an object's folder, the system examines the relationships between the subject and the target objects. It then examines the access rights 21 for the specified roles, and determines whether the subject has the rights to access the requested parts of the object's folder. Object Model Objects may be secured at many levels of granularity. At the most coarse level, the object to be secured may be the entire system, or a package. At the finest level, the object may be a single attribute value in a particular instance. Some of these objects are defined during system design and thus are part of the meta-data as shown in Table 2. Other objects are created during operation and are therefore part of the Operational data. Following are the types of objects that may be secured:
TABLE 2
Objects, Their Location in the System and Examples.
Secured
Object Location Example
System Contains all objects in the system
Package Meta-data All classes in the Clinical database.
Class Meta-data All instances in the Patient class
Folder Meta-data Patient John Doe's complete clinical
information
Provider Midtown Medical Center's
complete business information
Attribute Meta-data Patient Diagnosis attribute for all patients
in the Patient Class
Instance Operational Patient John Doe's instance
Data Appointment for John Doe on June 5,
1989
Attribute Operational Patient John Doe's Diagnosis
Value Data
Object classes are related to other object classes through relationship classes. These relationship classes are also object classes with their own attributes. For example, Table 3 shows the relationship classes and attributes that a healthcare system may have:
TABLE 3
Examples of Object Relationships Classes and their Attributes.
Relationship Class Relationship Class Attributes
Patient - Physician Physician Role, Start Date, End Date
Patient - Provider Account Number, Start Date, Accounts
Receivable
Provider - Physician Role, ID, Start Date, End Date
Patient - Family Relationship Type, Duration, Dependency
Member
Patient - Treatment Prescribed Medication
instances
Floor - Physician Role, Start DateTime, End DateTime
Patient - Floor Room Number, Start DateTime, End DateTime
Relationship instances link object instances. For example, any number of instances of patient-physician relationship exist, linking physician instances to patient instances. Object relationships play two key roles in the security system. Relationships between objects and their sub-objects create object folders. Relationships between subjects and objects form the basis of granting subjects access to their related objects. Parent-child Object Relationships Establish Folders Relationship classes define folders. For example, the patient's folder may consist of: Family member relationships Healthcare provider relationships and any owned instances of this relationship (e.g. charges and payments). Patient encounter instances and any instances owned by the encounter instances. Patient treatment instances and any instances owned by treatment instances. Securing the master instance in a folder preferably secures all the owned folder instances. For example, if access to a patient's instance is denied, access to the patient's treatment instances is automatically denied without requiring any further security specification. Folders may have subfolders. For example, a patient encounter may consist of dozens of sub-instances, which collectively form a folder. An operation performed during the encounter may itself be a subfolder. Securing a folder at any level secures all its subfolders. The relationship class may define limitations on accessing subfolders. For example, the patient-provider relationship class may indicate read-only access to the patient sub-folder. Thus, users who have access to the provider's folder can only have read-only access to the patient's subfolders. A logical system object forms a logical folder that owns all the objects in the system. The purpose of the system object is to allow access to objects that do not have any reason to have relationships to users. For example, generic tables such as information on drugs and diseases are accessible only through the system folder. Generally, only high level roles such as system administrator have full access to these objects, and most other system users have read-only access. Object Security Classifications Referring to FIG. 2, each object in a system 40 can be assigned a security classification label. The security classification label is a measure of the sensitivity of the information, and is the means through which access may be allowed or denied. Security classification labels can be linked and can be formed in a hierarchical structure. A security classification label A may have a parent label B, so that granting access to A automatically grants access to B and all antecedents of B. The labels towards the root 42 of the hierarchy are for less sensitive information and have a lower security rank, whereas labels towards the leaf 44 are more sensitive and have a higher security rank. When a subject is provided access to a more sensitive label, they also have access to the less sensitive labels that are its antecedents. For example, referring to FIG. 2, if a user has access to Patient Financial Sensitive 46 information, they also have access to Patient Financial 48 and Patient Common 50 information. The purpose of linking 5 security classification labels is to simplify the task of assigning access rights. There is no requirement in the system that all labels form a single hierarchy. In fact, the labels may form many different kinds of patterns: single stand alone labels, linear ranked lists, or hierarchies. Any number of such patterns may exist in a single secured system 40. Objects may be labeled with security classifications. Most of security classifications are on meta-data objects. More advanced security options may label operational data objects such as an instance or an attribute value. If an object is not assigned a security classification label, it inherits its security classification label. The source of its inheritance is shown in Table 4:
TABLE 4
Inheritance of Security Classifications
Secured Object If no direct label, then the label is inherited
Type from:
System --
Package Master Package (if any), Otherwise System
Class Stricter of Package or Super Class
Folder Owning Instance
Attribute Class
Instance/Record Class
Attribute Value Stricter of Instance or Attribute
The system object preferably always has a default security classification label. If an object in the system does not have a direct security label and has no ancestors that have a security label, then it inherits the security label of the system object. The security classifications for an instance or an attribute value may be obtained using derivation rules. For example, as shown with patient folder 52 in FIG. 3, the security classification for the patient diagnostic instance 56 may be derived from the sensitivity level of the problem diagnosed, thus allowing an extra level of security such as super sensitive 54 for patients diagnosed with certain types of diseases, such as HIV. Similarly, if an attribute in the patient's folder designates the patient as a VIP, the patient folder may be marked with a Patient VIP security label 53. A derived classification may be derived at the time the respective data is entered and stored as part of the instance, or it may be obtained at the time security is enforced. In other words, it may be persistent or non-persistent. Subject-object Relationships and Roles Subjects are a special class of objects that are the users of the system. Subject-object relationships form the basis of the access control of the present invention. As shown in system 60 of FIG. 4, relationships between subjects and objects provide the basis for access control of the present invention. If a subject has a relationship to an object, then it has access to the folder of that object. The type of relationship is the subject's role for the object, wherein the role defines the precise access rights for the subject. For example, relationship between physician "Dr. Smith" 12 and patient "John Doe" may define the role of Dr. Smith as primary care physician (PCP) 62. Mr. Smith now has access to John Doe's folder 64, and has the access rights defined for the role "Primary Care Physician." A subject may have any number of relationships. Each relationship has a unique role, which defines the precise rights that the subject has over the corresponding folders. For example, Mr. Smith may have a "Medical Director" role 66 at one provider having folder 67, an "Attending" role 68 at another provider, be the "Primary Care Physician" 62 for one patient, a "Specialist" role 70 for another patient, and act as a "Resident" role 72 for the General ward having folder 74. Each of these relationships brings precise access to corresponding folders. FIG. 4 shows an example of these relationships. Thus, a subject may have multiple relationships to the same object. For example, Dr. Smith may be the PCP for patient John Doe, a medical director for the provider who has the patient as a customer, and a resident for a ward where the patient is admitted. Each of these relationships defines a role for Dr. Smith and gives him specific rights to the Patient John Doe's folder. His full rights to this patient's folder is the aggregate of all such rights. Although it is stated herein that the role defines the access rights, it should be understood that the relationship name itself can equally define the role and its access rights. For example, a doctor can have a "primary care provider" relationship and an "attending physician" relationship with a patient and these relationships can define the doctor's access rights to the patient's information. Every subject preferably also has a relationship to the system, such as system user 76, which defines the basis for getting access to all the objects that the subject cannot access through any other relationship. This relationship is typically stored alongside the system's authentication information. A subject is also stored as an object in the system, and preferably has a self role to its own object. Each type of subject may have a different self role, and each such role may define how the subjects may access or manipulate its own information. For example, a patient may have read-only access to his entire folder, but can modify only his bio-data information. Roles and Access Rights Referring to FIG. 5, each role 78 is defined with a specific set of access rights 80 to the target objects that are exposed through the relationship. A role 78 may have any number of access rights. Each access right 80 specification preferably consists of a security classification 82 and a function classification 84. The security classification 82 indicates the type of objects that may be accessed through this right. The function classification 84 indicates the type or types of functions that may be performed on the object. Functions themselves can have a hierarchy, so that Full function includes the ReadWrite function, whereas the ReadWrite function includes the ReadOnly function. A generic set of such functions is defined by the system for all objects. In addition, each object may define its own set of functions. In addition to roles, subject/object relationships preferably have other contextual information or rules that control the access to the object. Almost certainly, a relationship is likely to have the start and end time of the relationship. Subject/object relationships have additional security rules that control the access based on contextual information. For example, a rule that allows security access starting on the start date/time of relationship, and ending 24 hours after the ending date/time may be represented in computer code as: Current_Date_Time BETWEEN Start_Date_Time AND (End_Date_Time+"24:00:00") Implementing the Present Invention The access control system may be implemented in a variety of ways. The options include: integrated as part of a database management system to secure access to the database objects. integrated in an object management system, such as an object request broker, to secure access to the objects accessed through the system. implemented in a specific application such as a healthcare application. implemented as a standalone security server. An example of a security server system 90 is shown in FIG. 6. Security System Design FIG. 6 shows an example of a security server. The steps for designing the security system design are: 1. Design a security classification hierarchy that serves the security needs of the organization. 2. Determine the necessary data 96. Design or reverse engineer the object classes and attributes of all the objects that need to be secured. Store these in meta-data 94. 3. Assure that object relationships are properly defined in the object model. Also mark the folder ownership to create logical folders. Store these in meta-data 94. 4. Mark all meta-data objects 94, i.e. packages, classes, attributes and functions, with appropriate security classifications. All unmarked objects will inherit their classifications. 5. Define a set of roles that encompass all the roles in all direct or indirect subject/object relationships in the system. Store these in meta-data 94. 6. Define a set of access rights for each role. Store these in meta-data 94. 7. Define context related security rules for each relationship. For example, if the relationship has a start and end date, then the rule may limit access only between those dates. Store these in meta-data 94. 8. Where required, define security rules to mark instance and attribute value security. Store these in operational data 96. This process defines all the meta-data requirements to enforce security. The system is now ready for operation. Security Administration Ongoing security administration needs with the present invention are comparatively limited. This administration can include when relationships are created between subjects and objects, such as assigning a physician to a patient or adding a user to the system, make sure that the role, start date/time, and end date/time are appropriately recorded. For the most part, this information alone drives the entire access enforcement process. For more advanced security, individual instances may be marked with their own security classification. For example, a VIP patient may have a top-secret classification. Additionally, some attribute values may be stamped with their security classification. For example, instead of marking the whole VIP patient instance, only the diagnosis may be marked secret. Flow Diagrams Methods for controlling access to information on a computer system are shown in FIGS. 7-9B. Referring to FIG. 7, the system is first provided 110 as described above. The method of access control 130 is initiated when a subject tries to perform an operation on an object. The system will obtain 112 an access request from a user for information about a data object. The access request preferably contains: 1) the subject class and ID (at this point, the subject is already authenticated); 2) the instance class and ID; 3) the attribute or a list of attributes that are being accessed; and 4) the function to be performed. The system will find 114 at least one of the relationships, if one exists, between the user and object. Alternatively, all the relationships that exist can be found. Generally, at least one relationship will be found, i.e. from the user to the system. If the user has other direct or indirect relationships to the object, additional relationships may be found. If only one of the relationships was initially found and access was not granted to the object, the system can continuously go back and find another relationship until it is conclusively determined that the user has access or does not. After the relationships have been found between the user and the object, determine 116 the security classification from the access rights for each relationship. This step may comprise obtaining the role from each relationship, then obtaining the list of access rights for the role. Alternatively, the relationship itself can state the type of relationship. An access right may also comprise a functional classification limiting the functions that the user can perform on the object. Next, determine the security classification labels for the object 118: For an instance security label, obtain the most restrictive of: the class label stored in the meta-data, the instance label stored in the operational data, or an instance label obtained from a security rule. For an attribute security label, obtain the most restrictive of: the attribute label class, the attribute label stored in the operational data, or an attribute label obtained from a security rule. If both an instance security label and an attribute security label exist, use the most restrictive of these. Next, determine if the user can be granted access to the data object. If the security classification of the relationship is greater than the data object's security classification, then grant the user access 122 to the data object. Otherwise, if the security classification of all the relationships are less than the data object's security classification, then deny the user access 124 to the data object. With the present invention, each relationship security classification can be compared with the security classification of the object until it is determined that the user has access. Alternatively, all relationship security classifications can be compared with the security classification of the object and the user access can be determined after the comparisons. By stating that the security classification can be "greater," it should be understood that greater is defmed as having a security level adequate to allow access to the data object. Additionally, other variations of methods can be used for determining the adequacy of the relationship's security level when compared to the data object's security level. For example, the system may require the user-object relationship to have a greater or equal security classification than the data object's security classification. If the access to the data object is granted, it is also possible to add an entry to an available access right list noting the functions that are allowed to be performed by the access right's function classification. If the function the user desires to perform on the object that is in the list of available rights, then return "Access granted". Otherwise, return "Access denied" and optionally return the functions that are available. If the user's request consisted of multiple objects, for example multiple instances or attributes, the system can return an appropriate response for each object. Referring to FIG. 8, a method for controlling access 130 can specifically include the steps of obtaining access 132 to the computer system and providing 134 and identification of the user. In this embodiment of the invention, the system determines each relationship 114 between the user and the data object and determines the security classification for all relationships. Furthermore, the system can determine if no relationships exist 136 between the object and the user and deny access 124 to the data object on that basis. Referring to FIGS. 9A and 9B, a method for controlling access 140 can also include rule based security classifications. The system will first determine if any security rules exist 148. If the instance has a non-persistent security label that is determined through one or more derivation rules, apply 150 the one or more rules to obtain the security labels. Depending on the needs of the system, the applicable security label can be the most or least restrictive of these security labels and the persistent security label. Preferably, however, the applicable security label is the most restrictive of these security labels. If the invention described herein is made useable for a computer, it can be stored on a computer usable medium having computer readable program code means embodied therein for completing the method. The computer readable program code means can include any type of computer language available or a representation of the computer language thereof, such as machine code, assembly language, compiler language, alphanumeric code or binary code. The computer usable medium can include any magnetic, electric or optical device for storing computer language, such as hard disks, floppy disks, CD-ROMS, optical drives or zip drives. It should be understood that the foregoing is illustrative and not limiting and that obvious modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, reference should be made primarily to the accompanying claims, rather than the foregoing specification, to determine the scope of the invention.
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