Access control for sensitive functions

TL;DR: In this paper, the authors propose a challenge/response mechanism to verify the correctness of a cryptographic algorithm in a data processing system against a user replacing a weak algorithm intended for the protection of data with a strong one intended for use by the security infrastructure.

Abstract: A data processing system has a security infrastructure, including a first cryptographic support facility, a security service for user data, including a further cryptographic support facility, and a number of cryptographic algorithms, usable by said cryptographic support facilities. In order to protect against a user replacing weak algorithms intended for the protection of data with strong algorithms intended for use by the security infrastructure, a challenge/response mechanism is provided, which enables the cryptographic support facilities to verify authenticity of the algorithms. The challenge/response mechanism is as follows. First, the cryptographic support facility sends a challenge to the algorithm. The algorithm then generates a response by applying a cryptographic function to the challenge, and returns the response to the cryptographic support facility. The cryptographic support facility then checks whether the response has an expected value. Only upon successful authentication does the algorithm reveal a pointer to a function table. The pointer is encrypted under a shared secret key to prevent an "attacker in the middle" attack.