Protecting memory interface

摘要

An apparatus includes an interface and logic circuitry. The interface is configured to communicate over a communication link. The logic circuitry is configured to convert between a first stream of plaintext bits and a second stream of ciphered bits that are exchanged over the communication link, by applying a cascade of a stream ciphering operation and a mixing operation that cryptographically maps input bits to output bits.

主权项

1. An apparatus comprising:
an interface, which is configured to communicate ciphered bits over a communication link; and logic circuitry, which is configured to convert between a first stream of plaintext bits and a second stream of the ciphered bits that are exchanged over the communication link, by applying a cascade of a stream ciphering operation and a mixing operation that cryptographically maps input bits to output bits, wherein the logic circuitry is configured to apply the mixing operation by multiplying the input bits by a respective non-constant mixing key in a Galois-Field (GF), and to iteratively update the mixing key in coordination with a remote apparatus at an opposite side of the communication link, by multiplying the mixing key in the respective GF by a constant element or by a GF multiplicative inverse of the constant element, such that at any given time the mixing key is the GF multiplicative inverse of a corresponding mixing key used by the remote apparatus.