Restricting access to content based on measurements of user terminal operational performance

A method comprising:

• performing operations as follows on a processor of a content server:
• for each of a plurality of user terminals, storing in a repository an initial terminal metric identifier, which is generated based on measurement of an operation performed by the user terminal, associated with a content identifier for content that is available through the content server and further associated with a user identifier;
• receiving content request messages from user terminals requesting access to the content available through the content server, each of the content request messages containing a user identifier and a content identifier;
• responsive to receiving one of the content request messages from one of the user terminals, determining a level of security defined by a security policy for one of the user identifier and the content identifier and selecting a plural defined number of different types of hardware features as a subset from among a superset of defined types of hardware features based on the determined level of security;
• communicating a terminal identifier challenge message to the one of the user terminals that identifies the subset of the plural defined number of different types of hardware features of the one of the user terminals, the terminal identifier challenge message requesting the one of the user terminals to generate a present terminal metric identifier based on measuring operational performance of each of the subset of the plural defined number of different types of hardware features identified by the terminal identifier challenge message;
• responsive to communicating the terminal identifier challenge message to the one of the user terminals, receiving from the one of the user terminals a challenge response message containing the present terminal metric identifier which is generated based on measurement the operational performance of each of the subset of the plural defined number of different types of hardware features identified in the terminal identifier challenge message performed by the user terminal;
• for each of the content identifiers in the repository,
• selectively granting access, through the content server to the content having the content identifier, for only ones of the content request messages that contain the present terminal metric identifier which matches the initial terminal metric identifier stored in the repository with an association to the content identifier in the repository matching the content identifier in the content request message and with a further association to the user identifier in the repository matching the user identifier contained in the content request message.