Cryptanalysis
Cribs and hypotheses
Also found as known plaintext · probable word · hypothesis mapping
A crib is a claim
A crib is plaintext suspected or known to occur somewhere in the ciphertext. Known plaintext has external support; a probable word may be only a good guess. Placement asks what would have to be true if the crib began at a chosen position.Gaines, CryptanalysisElements of Cryptanalysis
Placement creates consequences
For simple substitution, Decipher places a crib by Latin-letter position and derives ciphertext-to-plaintext mappings. Punctuation remains in the projection but does not consume a letter position. Baconian placement derives A/B class claims from groups in the carrier text.
- Claims
A→T Y→H Z→E- Projection
·T-HE
The dot is still unknown. The readable fragment is a consequence of the placement, not confirmation of it.
The hypothesis keeps claims separate
A hypothesis can combine one-to-one letter mappings, one-to-one Polybius token mappings, pair equations, cribs, and Baconian class claims. Disabled claims stay in the ledger without affecting the current result. Pair equations are retained as evidence but do not create a plaintext projection.
- Claims
42→M 32→E 51→T- Input
42 32 32 51 / 42 32- Projection
MEET ME
Polybius mappings can be tested in a hypothesis. The current Crib Tool does not provide Polybius placement.
A contradiction rejects the combination
Under a one-to-one substitution, A→T and A→E cannot both hold, and A→T with B→T also conflicts. Decipher keeps those claims and marks the affected projection instead of choosing one silently. Baconian same/different relations can carry a contradiction through a whole connected class group.
No contradiction means only that the active claims can coexist under the selected model. It says nothing about whether the crib is likely, the model is right, or the recovered fragment belongs in the message.