A note on redundancy in encrypted messages
Li Jing Gong · ACM SIGCOMM Computer Communication Review · 1990
In a cryptographic protocol, it is important for a recipient to determine that a message has not been modified during transmission. This is normally achieved by providing redundancy in the message. Typically, a message is described in the literature as containing enough redundancy, not enough redundancy, or no redundancy at all. This note shows that, because of the secrecy that comes with encryption, redundancy can be provided at two different levels. An example demonstrates that this distinction is useful in guarding against certain cryptographic attacks on weak keys.