jmm@miro.Berkeley.EDU (James Moore) (05/15/87)
Is knowing the original language of an encrypted message ever necessary for attempting to decipher it? James
rotondo@ernie.Berkeley.EDU.UUCP (05/15/87)
In article <18919@ucbvax.BERKELEY.EDU> jmm@miro.Berkeley.EDU (James Moore) writes: > > Is knowing the original language of an encrypted message ever necessary > for attempting to decipher it? It certainly is; for example, suppose you have a substitution cipher and you want to do a frequency analysis to find the most common letters. Which plaintext letters are most common varies from language to language. -- Scott
gwyn@brl-smoke.UUCP (05/17/87)
In article <18919@ucbvax.BERKELEY.EDU> jmm@miro.Berkeley.EDU (James Moore) writes: >Is knowing the original language of an encrypted message ever necessary >for attempting to decipher it? There are some systems for which one is likely to produce the correct plaintext without necessarily understanding it, but this is not a universal property of cryptosystems. Often one can reduce the message to a simple substitution without knowing what the language is. Going from there to plaintext generally requires some information about general characteristics of a language, although the analyst need not be highly proficient in it. I recall decrypting some messages in a simulation (part of a cryppy training exercise) that were in English but kept mentioning the "BANDITHUTH". Took me a while to realize that this was the bandit, Huth. (Spaces are often omitted in field systems.) Nonetheless I had correctly decrypted it without understanding what it meant.
levy@ttrdc.UUCP (Daniel R. Levy) (05/17/87)
In article <18924@ucbvax.BERKELEY.EDU>, rotondo@ernie.Berkeley.EDU (Scott Rotondo) writes: < In article <18919@ucbvax.BERKELEY.EDU> jmm@miro.Berkeley.EDU (James Moore) writes: < < Is knowing the original language of an encrypted message ever necessary < < for attempting to decipher it? < < It certainly is; for example, suppose you have a substitution cipher and < you want to do a frequency analysis to find the most common letters. < Which plaintext letters are most common varies from language to language. A code attack which had to guess the language would be harder (N cracking attempts presuming N different languages, N large and finite) but definitely not impossible. Perhaps the N-attempt requirement would put a cracking attempt beyond practical feasibility if the code was already tough, however. (Does this make any sense or am I just talking through my hat?) -- |------------dan levy------------| Path: ..!{akgua,homxb,ihnp4,ltuxa,mvuxa, | an engihacker @ | vax135}!ttrdc!ttrda!levy | at&t computer systems division | Disclaimer: try datclaimer. |--------skokie, illinois--------|