Attacking the IETF/ISO Standard for Internal Re-keying CTR-ACPKM

Encrypting too much data using the same key is a bad practice from security perspective. Hence, it customary to perform re-keying after given amount of transmitted. While in many cases, done fresh execution some exchange protocol (e.g., IKE or TLS), there are scenarios where internal re-keying, i.e., without information, performed, mostly due performance reasons.Originally suggested by Abdalla and Bellare, several proposals on how this mechanism. For example, Liliya et al. offered CryptoPro Key Meshing (CPKM) be used together with GOST 28147-89 (known as block cipher). Later, ISO IETF adopted Advanced (ACKPM) 10116 RFC 8645, respectively.In paper, we study ACPKM CPKM. We show that suffers an entropy loss successive repetitions rekeying attacks based issue. The most prominent one has time complexities O(2κ/2) success rate O(2−κ/4) for κ-bit key.Furthermore, malicious cipher designer faulty implementation can exploit (or original CPKM) mechanism significantly hinder employing CPKM). Namely, such re-keyed greatly reduced.