A Secure Self-synchronized Stream Cipher
This work addresses security vulnerabilities in self-synchronized stream ciphers for cryptographic applications, representing an incremental improvement by building on prior contributions.
The paper tackles the problem of self-synchronized stream ciphers lacking strong security by introducing a new security model (LORBACPA+) that is stronger than existing ones, and proposes a new cipher proven secure in this model, addressing vulnerabilities in standard constructions like delayed CBC.
We follow two main objectives in this article. On the one hand, we introduce a security model called LORBACPA$^+$ for self-synchronized stream ciphers which is stronger than the blockwise LOR-IND-CPA, where we show that standard constructions as delayed CBC or similar existing self-synchronized modes of operation are not secure in this stronger model. Then, on the other hand, following contributions of G.~Millérioux et.al., we introduce a new self-synchronized stream cipher and prove its security in LORBACPA$^+$ model.