Re: Non-Scalar Cryptography - The Emporor is stark naked.

On Wed, 14 May 2008 11:03:14 -0700 (PDT), AdaCrypt
<austein.obyrne@xxxxxxxxxxxxxx> wrote:

The algorithm is:

(Plaintext +key) Mod 95 = Ciphertext Mod 95
The second mod 95 is redundant:
(plaintext + keystream) mod 95 = ciphertext


Analysing the key probability as you have done will not affect the
uncertainty of the ciphertext => the ciphertext still has equal
probability between elements = > the ciphertext string is random by
definition surely => this is the backbone of this cipher - whether it
is an OTP or not is not important ?? - I am taking on board your
suggestion regarding a standalone cipher - Thanks for your help
The key *size* is important. To take an extreme example, assume that
the scrambling key is an absurdly small 16 bits; that means that there
are only 65536 possible different values of the key, so there are only
65536 possible different permutations that your scrambling algorithm
can generate from that size key. An attacker can brute-force that
number of permutations reasonably quickly. There are many potential
permutations, but you are only able to use the permutations generated
by your scrambling key. The bigger the key, the bigger the number of
possible permutations, up to about 2800 bits. After that point you
will have key pairs which generate the same permutation from different
keys.

The permutation generated by your scrambling key does not have equal
probability between the elements since the probability of an element
appearing is dependant on the number of times that element has already
appeared in the permuted list of 14,000 characters. This is a
potential source of weakness.

rossum

.

Relevant Pages