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The following archive was created by hippie-mail 7.98617-22 on Thu May 27 1999 - 23:44:21
mgraffam@idsi.net
Wed, 7 Apr 1999 18:22:04 -0400 (EDT)
On Wed, 7 Apr 1999, Mok-Kong Shen wrote:
> However, on p.21 of the Handbook by Menezes et al. one reads:
<clipped for brevity>
> Thus (1) the Vernam cipher is a stream cipher, (2) a Vernam cipher
> does not necessarily have to do with the one-time pad. In my humble
> understanding the majority of present day stream encoding is performed
> at the bit level with XOR and is hence Vernam cipher.
I agree with (1) .. a Vernam cipher IS a very special stream cipher.
However.. I take issue with the idea that a Vernam cipher MUST use
XOR, further a periodic key stream is a Vigenere cipher, not a Vernam.
A one-time pad is no less a one-time pad if it uses simple addition
instead of XOR. It works the same way, and has all of the same
properties, strengths and flaws.. with the one exception that one needs
subtraction to decrypt.
I therefore take exception with (2) in Handbook of Applied Cryptography.
That the mistake was made in an important work of modern cryptography is
embarrasing, but it is still a mistake.
Michael J. Graffam (mgraffam@idsi.net)
The following archive was created by hippie-mail 7.98617-22 on Thu May 27 1999 - 23:44:21