Take the 2-minute tour ×  Is it possible to tell which
encryption algorithm was used, assuming I have a key and a
encrypted text?  To not complicate the situation let assume we
are speaking about symmetric algorithms only.  Are there any
common methods to discover encryption method?  share|improve
this question possible duplicate of Is it possible to derive the
encryption method from encrypted text? –  e-sushi Dec 20 '13 at
12:23 add comment  1 Answer  up vote 0 down vote accepted  The
normal method is to reverse-engineer whatever software produces
or consumes the ciphertext. The underlying idea is that in a
practical attack situation, the attacker has some known interest
in breaking the system; there is context. The context usually
indicates what kind of algorithm is in use.  In some cases where
the code to reverse-engineer is not immediately apparent, other
clues can be gathered. For instance, a smart card which can
encrypt data at relatively high speed must necessarily use some
dedicated hardware, so data