Provable Security of Authenticated Encryption Schemes

Abstract

Denne bacheloroppgaven ser på den bevisbare sikkerheten til randomized counter mode (RCM) og Galois counter mode (GCM). Dette gjøres ved å bruke sekvenser av spill for å strukturere bevisene. Vi vil bevise at randomized counter mode er CPA-sikker under PRF-antakelsen, og vi vil bevise at GCM er nonce-basert AEAD-sikker under antakelsen at den underliggende blokkchifferen er en sikker PRF og at nøkkel-hash-funksjonen GHASH er en XOR-DUF.

This bachelor thesis studies the provable security of the randomized counter mode (RCM) and the Galois counter mode (GCM). This is done by making use of sequences of games to structure our proofs. We will prove that the randomized counter mode is CPA-secure under the PRF assumption, and we will prove that the GCM is nonce-based AEAD-secure under the assumption that the underlying block cipher is a secure PRF and that the keyed hash function GHASH is an XOR-DUF.