| (I) The mathematical science that deals with analysis of a
cryptographic system in order to gain knowledge needed to break or
circumvent the protection that the system is designed to provide.
(See: cryptology.)
(O) "The analysis of a cryptographic system and/or its inputs and
outputs to derive confidential variables and/or sensitive data
including cleartext." [I7498 Part 2]
(C) The "O" definition states the traditional goal of
cryptanalysis--convert the ciphertext to plaintext (which usually
is cleartext) without knowing the key--but that definition applies
only to encryption systems. Today, the term is used with reference
to all kinds of cryptographic algorithms and key management, and
the "I" definition reflects that. In all cases, however, a
cryptanalyst tries to uncover or reproduce someone else's
sensitive data, such as cleartext, a key, or an algorithm. The
basic cryptanalytic attacks on encryption systems are ciphertext-
only, known-plaintext, chosen-plaintext, and chosen-ciphertext;
and these generalize to the other kinds of cryptography.
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