Abstract: Returning rows having column values masked is disclosed. In response to receiving a database command, a modified database command is created that specifies whether to mask a value by returning a mask of the value instead of the value. In an embodiment, the condition expression is included in a policy function that is referenced by a policy. In an embodiment, the policy determines how the condition expressions are used. The condition expression may be used to determine which column values to mask. The condition expression may also be used to filter which rows are returned.

Abstract: One embodiment of the present invention provides a system for establishing multiple sessions between a database and a middle-tier client. During operation, the system receives a request for a plurality of sessions at a database from a middle-tier client. In response to the request, the system authenticates the middle-tier client, and creates a session between the database and the middle-tier client. The system clones the session one or more times to create the plurality of sessions. Finally, the system sends a plurality of session-handles associated with the plurality of sessions to the middle-tier client. This enables the middle-tier client to distribute the session-handles to end-user clients in response to subsequent requests from the end-user clients to access the database.

Abstract: A fine-grained access control mechanism uses policy functions that are associated with a database object (e.g. table and view). The policy functions are invoked, when, for example, a database server detects that a query is issued against the database object. The value of a policy function remains constant under certain conditions. For example, once a database server is brought up, the value of a policy function may remain the same. Users can specify the conditions under which the value of a policy function remain constant. Based on this information, when a policy function is computed while processing a query, the database server caches the value of the policy function. When processing another query that requires the value of the policy function, the database server retrieves the result from the cache rather than re-computing the policy function, as long as the condition under which the policy function remains constant persists.

Abstract: One embodiment of the present invention provides a system that selectively audits accesses to a relational database. The system receives a query at the relational database and modifies the query so that processing the query causes an audit record to be created and recorded for rows in relational tables that are accessed by the query and that satisfy an auditing condition. Next, the system processes the modified query to produce a query result. This processing causes an audit record to be created for rows in relational tables that are accessed by the query and that satisfy the auditing condition. The system records the audit record in an audit record store, and then returns the query result. In one embodiment of the present invention, if the query includes a select statement, the system inserts a case statement into the select statement. This case statement calls a function that causes the audit record to be created and recorded if the auditing condition is satisfied.

Abstract: One embodiment of the present invention provides a system that selectively audits accesses to a relational database system. This system starts by receiving a query from a client at a database server. The system processes this query at the database server to produce a query result. The system also creates an audit record for rows in relational tables that are accessed by the query, and that satisfy an auditing condition. Next, the system records the audit record in an audit record store and returns the query result to the client. Integrating the auditing facility into the relational database system in this manner ensures that auditing is performed in the same way regardless of which application generates the query. Furthermore, this auditing is transparent to applications and users.

Abstract: One embodiment of the present invention provides a system that protects data from unauthorized modification in a table, wherein the table contains one or more rows, and wherein each row contains one or more columns. During operation, the system chooses in a row one or more columns to be protected. The system then produces an encrypted value for the row based on the data stored in the chosen columns. Next, the system stores the encrypted value in a column which cannot be easily modified. In this way, a later-produced encrypted value generated from the values in the protected columns can be compared against the previously stored encrypted value to verify the integrity of the data stored in the protected columns.

Abstract: One embodiment of the present invention provides a system for sharing a security context between different sessions on a database server. The system operates by receiving a request at the database server through a database session between the database server and an application on a database client. The system looks up an identifier for an application client that was previously associated with the database session. The system uses this identifier to look up the security context containing attributes related to the application client within a storage area associated with the database server. Next, the system performs a database operation to satisfy the request and in doing so enforces access rights associated with the security context. In one embodiment of the present invention, the request includes a database query directed to a database on the database server.

Abstract: A fine-grained access control mechanism uses policy functions that are associated with a database object (e.g. table and view). The policy functions are invoked, when, for example, a database server detects that a query is issued against the database object. The policy functions return optimizer hints, which are added to the query.

Abstract: A fine-grained access control mechanism uses policy functions that are associated with a database object (e.g. table and view). The policy functions are invoked, when, for example, a database server detects that a query is issued against the database object. The value of a policy function remains constant under certain conditions. For example, once a database server is brought up, the value of a policy function may remain the same. Users can specify the conditions under which the value of a policy function remain constant. Based on this information, when a policy function is computed while processing a query, the database server caches the value of the policy function. When processing another query that requires the value of the policy function, the database server retrieves the result from the cache rather than re-computing the policy function, as long as the condition under which the policy function remains constant persists.

Abstract: A fine-grained access control mechanism uses policy functions that are associated with a database object (e.g. table and view). The policy functions are invoked, when, for example, a database server detects that a query is issued against the database object. The policy functions return optimizer hints, which are added to the query.

Abstract: Described is a technique for controlling access to data in a database system. Groups of security policies are established for a database schema object, such as a table or a view. A security policy reflects access rules for accessing the database schema object. Access to the database schema object is restricted based on security policy groups selected for the user. The security policy groups are selected based on information associated with a user that is maintained or accessed by the database system. A default security policy is established and used to restrict access of users accessing the database schema object. The information associated with the user contains an attribute that identifies a policy group. The database management system uses the attribute to select policy groups that restrict the user's access to the database scheme object.