Take the 2-minute tour ×  Lets say you are presented with an
encrypted string of bits or text, and no other information. What
would be necessary before you could apply brute force methods to
decrypting the string? How would a cryptanalyst approach such a
case? (lets assume the conditions are such that the encryption
can be brute forced in a reasonable time frame).  share|improve
this question  2 Answers 2  up vote 8 down vote accepted  This
is called ciphertext-only cryptanalysis*, and it's pretty
difficult unless the cipher is quite weak. Therefore, the first
priority for a cryptanalyst in such a situation is usually to
try to find more information about the algorithm. Fortunately
(for the cryptanalyst), as Kerckhoff's principle suggests, there
are often ways to find out how the algorithm works. For example:
• If the string was encrypted (or meant to be decrypted) by a
computer program, one could try to obtain a copy of the program
and inspect it in a debugger to determine the algorithm.    •
Similarly, i