Re: one time pad without xor

From: John Bailey (john_bailey_at_rochester.rr.com)
Date: 04/07/05 

Date: Thu, 07 Apr 2005 12:19:02 GMT

On 4 Apr 2005 22:13:38 -0700, "Pius XI" <belleza_j@yahoo.com> wrote:

>I was wondering if using modular addition instead of exclusive-or to
>combine the key and plaintext in a stream cipher would be of any
>cryptographic significance.
SIGNIFICANCE is ambiguous in this context. As other replies
indicated, the general method you describe is well known. It is not
quite as clearly known but a bitwise simple OR logical function can be
used with a one time pad. In this case, the recovered plaintext (as a
stream of bits) is noisy but due to the perfect security of a one time
pad, enough redundancy can be used such that the originally intended
message may be recoverable. An example of this is explained at:
http://home.rochester.rr.com/jbxroads/interests/sci.crypt/graphic_otp/

In this case, the significance is the graphic otp allows recovering
the message with a simple overlay of transparencies, eliminating
dependence on software or automation.

John Bailey
http://home.rochester.rr.com/jbxroads/mailto.html

Relevant Pages

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