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RE: Rest of World encryption hardware products?
Paul Koning writes:
> A Vernam cypher has a random key of length equal to the plaintext.
> Period. Full stop. Then and only then will it have the "provably
> unbreakable" property that makes it unique among cryptosystems.
Handbook of Applied Cryptography by Menezes, van Oorschot and
Vanstone defines Vernam cipher as follows:
The Vernam Cipher is a stream cipher defined on the alphabet
A = {0, 1}. A binary message m1 m2 ... mt is operated on by a
binary key string k1 k2 ... kt of the same length to produce a
ciphertext string c1 c2 ... ct where ci = mi XOR ki, 1 <= i <= t.
If the key string is randomly chosen and never used again, the
Vernam cipher is called a one-time system or a one-time pad.
The definition of stream cipher does not require that the
keystream be random.
- Erkko Lehtonen
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