On multivariate public keys based on a pair of transformations with density gap

Abstract

Families of stable cyclic groups of nonlinear polynomial transformations of affine spaces K n over general commutative ring K of increasing with n order can be used in the key exchange protocols and related to them El Gamal multivariate cryptosystems. We suggest to use high degree of noncommutativity of affine Cremona group and modify multivariate El Gamal algorithm via the usage of conjugations for two polynomials of kind g k and g −1 given by key holder (Alice) or giving them as elements of different transformation groups. We present key exchange protocols based on twisted discrete logarithms problem which uses noncommutativity of semigroup. Recent results on the existence of families of stable transformations of prescribed degree and density and exponential order over finite fields can be used for the implementation of schemes as above with feasible computational complexity. We introduce an example of a new implemented quadratic multivariate cryptosystem based on the above mentioned ideas.

On new stream algorithms generating sensitive digests of computer files

“…Theorem 1 (see [20]). For each natural integer m≥2 there exists homomorphism ψ: F'(K)→CSm(K) such that its of the order of G. Noteworthy that the proposition defines rare mathematical object.…”