Decoding Running Key Ciphers

There has been recent interest in the problem of decoding letter substitution ciphers using techniques inspired by natural language processing. We consider a different type of classical encoding scheme known as the running key cipher, and propose a search solution using Gibbs sampling with a word language model. We evaluate our method on synthetic ciphertexts of different lengths, and find that it outperforms previous work that employs Viterbi decoding with character-based models.

• Type: Journal
• Year: 2012
• Where: ACL
• Authors: Sravana Reddy, Kevin Knight
• Keywords: ACL 2012, Computational Linguistics, Gibbs Sampling, Natural Language Processing, Substitution Ciphers