System and method for authenticating remote execution

A system which validates software executing on a remote system having programmable processor, comprising:

• a challenge generator adapted to initiate a series of authentication checks, sending a series of checkpoints, for which respective authentic signatures are known;
• the checkpoints being adapted to be processed by a checkpoint enabling module executing on a remote server, which dynamically inserts calls to functions for generating respective control flow signatures at the checkpoint location during execution of a program being validated, and then restoring execution of the program being validated wherein the dynamically inserted calls have a non-predetermined location within a program, and are inserted without changing a size of the program code;
• and
• a control flow signature verifier adapted to verify a respective control flow signature based on a respective checkpoint, and verify that a control flow signature received from a remote server matches an expected signature for the respective checkpoint.

A method of verifying execution of a program on a remote server, comprising:

• identifying the locations of a set of control flow checkpoints and their associated expected signatures during execution of a program on a remote server;
• sending a list of randomly or pseudorandomly chosen checkpoints to the remote server;
• dynamically inserting calls into the program at the respective checkpoint locations during a runtime execution of the program;
• sending an alternate list of randomly or pseudorandomly chosen checkpoints to the remote server, wherein the alternate list identifies different randomly or pseudorandomly chosen checkpoints than the list;
• and dynamically inserting calls into the program at the respective checkpoint locations corresponding to the alternate list, prior to a subsequent runtime execution of the program;
• calling a signature verification function at the respective checkpoint locations;
• capturing control flow information, for each call corresponding to a checkpoint;
• generating a control flow signature corresponding to the control flow information;
• restoring a normal execution of the program;
• and
• communicating the control flow information from the remote server to an authentication server, for comparison with an authentic control flow signature corresponding to the checkpoint.

A method of generating a control flow signature in response to a function call, comprising:

• upon the function call from a program during execution, collecting signature-specific information and generating a signature selectively based on a current checkpoint location of a program being verified;
• generating a control flow signature in response to a function call inserted prior to subsequent program execution in an alternate checkpoint location within the program whose execution is being verified, the function call replacing at least one original program instruction;
• communicating an encrypted representation of the signature in conjunction with a session tag to an authentication server;
• receiving a message from the authentication server and selectively responding to the message;
• patching the program whose execution is being verified at a checkpoint location preceding the current checkpoint location or the alternate checkpoint location, to permit correct future generation of signatures at the checkpoint location preceding the current checkpoint location;
• and
• selectively resuming operation of the program being verified to execute an instruction subsequent to the function call, in response to the message.

A method of generating a control flow signature in response to a function call inserted during program execution in a checkpoint location within a program whose execution is being verified, the function call replacing at least one program instruction, comprising:

• upon the function call, collecting signature-specific information and generating a signature selectively based on a current checkpoint location of a program being verified;
• generating a control flow signature in response to a function call inserted during subsequent program execution in an alternate checkpoint location within the program whose execution is being verified, the function call replacing at least one original program instruction;
• communicating an encrypted representation of the signature in conjunction with a session tag to an authentication server;
• receiving a message from the authentication server and selectively responding to the message;
• and
• selectively resuming execution of the program being verified after the current checkpoint location or the alternate checkpoint location in response to the received message.