Re: A new public key algorithm based on avalanche properties

From: Jim Steuert (pjsteuert_at_rcn.com)
Date: 07/01/03


Date: Tue, 01 Jul 2003 00:30:23 -0400


Tom St. Dennis said:
>
> Actually there are no inverses if the determinant is not a unit.
>

Hi Tom,
   You are correct. The definition of unit is that it has
an inverse. The determinant of such a value must be a unit,
since the formula for inverse involves determinant^-1. It is not
enough for it to be non-zero. The additive zero is just a special case.
And I don't claim to be an abstract algebra expert, although I have
picked up pieces here and there when I'm interested.

  Still, I believe that the much simpler avalanche-based
public key exchange algorithm (which I have coded and tested as well)
in my post earlier today is secure, although it is not based on
commutative algebra at all. It is entirely based on the mixers being
homomorphic
transformations and the idea of hiding the x_global in the middle of the
avalanche.

  What I was discussing about rings was my "other" public key algorithm
ideas
based on commutative rings. The mixers in the avalanche.c algorithm are not
commutative (they don't need to be for avalanche only), and my original pdf
diagram
was wrong in that it was not really commutative. A "commutative" mixer
would
be a 2-input, 2-output mixer like:

 (x',y') = (a,b)*(x,y) = (ax+by,-bx+ay) in the a+b*sqr(-1) ring
   or like:

 (x',y') = (a,b)*(x,y) = (a+b*sqr(17))*(x+y*sqr(17)) = ( a*x+17*b*y,
a*y+b*x )
     in the a+b*sqr(17) ring.

where by "commutative" one can follow one multiplication operation say, by
(a,b) with another by (c,d) and the result is the same
as if you multiplied by (a,b) and then followed by (c,d). So that
multiplication is commutative. No two-input one-output mixer can
ever be commutative in that sense.

  This "other" public key algorithm is based on the observation that a
commutative ring for which some values are not units (have no inverse) can
be
used to create complex functions which are not easily invertible, either
in a alice/bob commutative sense, or in an avalanche, by using this as the
basic
multiplication mixer operation, and then things like a+b*sqr(17) as a ring
where
a and b are defined as the tabular "lossy" 3-bit commutative ring elements
(see included tables below).

  Likewise, an 8-input/8-output commutative ring mixer could be defined
as multiplication of two or more 8-dimension vector quantities like:

 v = a+b*sqr(q)+c*sqr(r)+d*sqr(s)+e*sqr(qr)+f*sqr(qs)+g*sqr(rs)+h*sqr(qrs)

where multiplication by another 8-part vector is the mixing operation.

and where q, r, and s are primes, and where the 8 values a,b,c,d,e,f,g,h
are
themselves ring elements defined as above, or with another commutative ring
definition like the 3-bit tabular one below. That is what I meant by
"nested definition" of rings. This is just some interesting rings I found
in Schaum's, as applied to this mixer idea. By virtue of this tabular
ring not having multiplicative inverses, I "think" that would make this
thing not easily divisible and thus the mixer would not be easily
invertible (many-to-one).

 I found the following tabular commutative ring in Schaum's outline series
"Modern Abstract Algebra", for which b,e,f are not units,
and e=g^-1, d=d^-1, g=c^-1, and h=h^-1 are units (a is the zero),
and h is the multiplicative unity. It can be used to encode 3-bit values.

+ abcdefgh
----------
a|abcdefgh
b|badcfehg
c|cdefghab
d|dcfehgba
e|efghabcd
f|fehgbadc
g|ghabcdef
h|hgbadcfe

* abcdefgh
----------
a|aaaaaaaa
b|aefbaefb
c|afdgebhc
d|abghefcd
e|aaeeaaee
f|aebfaebf
f|afhcebdg
g|abcdefgh

  -Jim

On Tue, 01 Jul 2003 01:45:35 GMT, Tom St Denis <tomstdenis@iahu.ca> wrote:

> Jim Steuert wrote:
>> Some of the rings in the sequence of definitions
>> are "lossy" in the sense that there is no multiplicative
>> inverse for some values. One example is the ring a + b*sqr(17)
>> module 2^k. That ring is isomorphic to the set of 2x2 matrices
>> of the form ( a, b, 17b, a ). There is no inverse when the
>> determinant (a^2-17b^2) is zero mod 2^k. There are other
>> more simple tabular examples.
>
> Actually there are no inverses if the determinant is not a unit.
>
> Might want to revise your algebra a tad :-)
>
> Tom
>
> [Coming from the person [me] who routine gets low marks in Algebra you
> may want to rethink your approach to cryptography as well!]
>
>



Relevant Pages

  • Re: AES and groups
    ... operator with identity and inverses. ... A ring is a set closed under two ... Nonsingular square matrices form a group under multiplication. ... DES isn't a group, and the group generated by DES contains at least ...
    (sci.crypt)
  • Re: Magic Flight: A New Public Key Algorithm stronger? than factoring
    ... > linear combination of rows that provides a pivot. ... use the row beginning with '2' as the pivot. ... multiplicative inverses. ... >> In the tabular commutative ring example ...
    (sci.crypt)
  • Re: Rings, Restatement of earlier problem
    ... >Find a ring with an element that has 2 left inverses. ... there is only one input giving this value, ... get a ring with multiple left inverses. ...
    (sci.math)
  • Re: Rings, Restatement of earlier problem
    ... > Find a ring with an element that has 2 left inverses. ... These elts are the right unit zero-divisors, ...
    (sci.math)