The 1944 Bletchley Park Cryptographic Dictionary

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DECRYPT :

To decode or decipher (a code or cipher message) cryptographically.

DECRYPTION :

The action or process of decoding or deciphering.

DEDUPE :

To remove (normally the less reliable or less complete) duplicate copies of cipher texts from (a quantity of traffic), esp. before Freeborning.

DELIVERY GROUPS :

Code groups for route instructions and addresses of code and cipher messages.

DE-PSI, v :

(used for). To set the psi-wheels in a Tunny message with the help of machines after it has been de-chied.

DEPTH :

1. A series of code messages reciphered with the same, or the same part of a, reciphering key especially when written under one another so that all the groups (usually one in each message) that are reciphered with the same group of the subtractor lie under each other and form a 'column'.

(b) two or more messages in a transposition cipher that are of the same length and have been enciphered on the same key;

(c) two or more messages in a machine or similar cipher that have been enciphered on the same machine-setting or on the same key.

2. be in depth: (of messages). Stand to each other in any of the relationships described above.

DEPTH CHART :

A diagram showing the position of (reciphered code) messages on the key, and thus indicating the depth at any given point.

DEPTH-CRIBBING :

(in Enigma) = Fun and Games.

DERECIPHER :

To strip off the subtractor or other form of recipherment from a re- ciphered message.

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