Although frequency analysis is a powerful and general technique
against many ciphers, encryption has still been often effective in
practice; many a would-be cryptanalyst was unaware of the technique.
Breaking a message without using frequency analysis essentially
required knowledge of the cipher used and perhaps of the key involved,
thus making espionage, bribery, burglary, defection, etc. more
attractive approaches to the cryptanalyticly uninformed. It was finally
explicitly recognized
|