As mentioned in Security,
often the job of the cryptanalyst to decrypt certain data is made much easier whenever
error that occurred is not handled properly and results in a 'leak'.
Error in Encryption leads to Compromises
When message-handling operator makes error in encrypting data. Compromises may occur
during requested re-transmission in these cases:
- This message can be encrypted using a different key. In any case, it is possible for
interceptors to compare the two ciphertext and work out the encryption.
- Sometimes, two identical messages encrypted with two keys, one old key known to the
interceptor and one new, may also be fatal.
- When a request for re-transmission results in transmission of plaintext, instead of a
repeat of the ciphertext.
Human Operator Errors
Most of encryption method that has been broken, was solved as a result of a tiny error on
the part of the cipher officer. Since the nature of the profession is such that a crypto
clerk needs to be deliver a flawless service to an organisation of considerable importance
to the state, in war times, this group of people received pressure of time and demand for
ultimate secrecy. Hence certain errors occurred as a result.
These errors include:
- Frequent use of words naturally occurring in certain type of activity may give a big
clue to any cryptanalyst. Hence messages should have been paraphrased in such manner that
the use of these words is as minimal as possible.
- The use of immutable words for certain sudden occurrence or perhaps events that may have
been triggered on purpose by the interceptor. The sequence of these words is looked out
for by potential cryptanalysts.
- The use of less likely occurring characters to represent null spacings.