International Association for Cryptologic Research (IACR)
Abstract
We study the security of authenticated encryption based on a stream cipher and a universal hash function. We consider ChaCha20-Poly1305 and generic constructions proposed by Sarkar, where the generic constructions include 14 AEAD (authenticated encryption with associated data) schemes and 3 DAEAD (deterministic AEAD) schemes. In this paper, we analyze the integrity of these schemes both in the standard INT-CTXT notion and in the RUP (releasing unverified plaintext) setting called INT-RUP notion. We present INT-CTXT attacks against 3 out of the 14 AEAD schemes and 1 out of the 3 DAEAD schemes. We then show INT-RUP attacks against 1 out of the 14 AEAD schemes and the 2 remaining DAEAD schemes. We next show that ChaCha20-Poly1305 is provably secure in the INT-RUP notion. Finally, we show that 4 out of the remaining 10 AEAD schemes are provably secure in the INT-RUP notion
