Quagmire ciphers, group theory, and information: Key amplification in crib-based attacks

ePrint Report: Quagmire ciphers, group theory, and information: Key amplification in crib-based attacks

Thomas Kaeding

We demonstrate how to apply some ideas from group theory to quagmire ciphers. Techniques are shown for amplifying one's knowledge of the keys. This is useful when breaking a ciphertext with a crib. The basic idea is that only a small amount of information goes into building a key table for a quagmire cipher, so we should only need that much information to reconstruct it.

amplification attacks ciphers eprint report information key theory