Substitution Cipher Breaker


scb [flags] trigram-stat-file  dictionary-file  cipher-text-file 
Tries to decrypt the substitution cipher encrypted cipher-text-file. It works reliable for texts of 150 characters and more. Lengthy cipher texts slow the program down, though. The cipher-text-file must contain word separators. The program outputs two suggestions of what the plain text might be together with a "history" of how these results were derived.


Print debugging information to stderr.
-r rounds
Specify the number of times ("rounds") we do hillclimbing.
-p penalty
Specify a penalty for illegal trigrams (default: -1000). We recommend to use the negative frequency of the trigram: "the". "penalty" is used by the trigram scorer.
-l linelength
Specify the approximate length of a plain text line on your display (default: 75).
-m maxlength
Specify the maximal length of words in the dictionary. Longer ones will be truncated (default: 9). "maxlength" is used by the dictionary scorer.
-w weight
Specify the weight for the dictionary scorer (default: 2).

The trigram-stat-file

The trigram-stat-file is an ascii file that has been generated by the statistic tool .

The dictionary-file

The dictionary-file is an ascii file that has one word per line. Only lowercase letters are allowed.

The cipher-text-file

The ciphertext-file is an ascii file. Only lowercase letters, space, and newline may used. Newlines are ignored, though. It is expected that words are separated by a word separator character that might be different from space.
Last Update: 15.04.96 (Format: DD.MM.YY)