Source : Webster's Revised Unabridged Dictionary (1913)

Decipherer \De*ci"pher*er\, n.
   One who deciphers.

Source : WordNet®

decipherer
     n 1: the kind of intellectual who converts messages from a code
          to plain text [syn: {decoder}]
     2: a reader capable of reading and interpreting illegible or
        obscure text