TY - JOUR
T1 - Breaking Substitution Ciphers Using a Relaxation Algorithm
AU - Peleg, Shmuel
AU - Rosenfeld, Azriel
PY - 1979/11/1
Y1 - 1979/11/1
N2 - Substitution ciphers are codes in which each letter of the alphabet has one fixed substitute, and the word divisions do not change. In this paper the problem of breaking substitution ciphers is represented as a probabilistic labeling problem. Every code letter is assigned probabilities of representing plaintext letters. These probabilities are updated in parallel for all code letters, using joint letter probabilities. Iterating the updating scheme results in improved estimates that finally lead to breaking the cipher. The method is applied successfully to two examples.
AB - Substitution ciphers are codes in which each letter of the alphabet has one fixed substitute, and the word divisions do not change. In this paper the problem of breaking substitution ciphers is represented as a probabilistic labeling problem. Every code letter is assigned probabilities of representing plaintext letters. These probabilities are updated in parallel for all code letters, using joint letter probabilities. Iterating the updating scheme results in improved estimates that finally lead to breaking the cipher. The method is applied successfully to two examples.
KW - cryptography
KW - probabilistic classification
KW - relaxation
KW - substitution ciphers
UR - http://www.scopus.com/inward/record.url?scp=0018542506&partnerID=8YFLogxK
U2 - 10.1145/359168.359174
DO - 10.1145/359168.359174
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AN - SCOPUS:0018542506
SN - 0001-0782
VL - 22
SP - 598
EP - 605
JO - Communications of the ACM
JF - Communications of the ACM
IS - 11
ER -