improvements in the application of bilinearen graphs in cryptographic applications

摘要

Cryptographic methods are known that involve the computation of a non-degenerate bilinear mapping of first and second elements (P 1 , Q 1 ) one of which comprises a secret of a first entity (A). For a mapping implemented as, for example, a Tate pairing, the mapping is computable by applying a predetermined function (f) to the first and second elements (P 1 , Q 1 ) and then exponentiating the result with a known exponent (e pub ). Improvements in respect of computational loading, size of output, and security are enabled for the first party (A) by arranging for the first entity to carry out (12) only part of the mapping, a second entity (B) being used to complete computation (13) of the mapping. Cryptographic applications using these improvements are also disclosed.