Abstract:
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.
Abstract:
A method of processing information (INFO) to be confidentially transmitted from a first module (C) to a second module (D) provides that a first scalar multiplication (SCAL-MLTr) may be carried out in order to obtain a first result [r]P) . This first scalar - multiplication comprises a plurality of generation steps of ordered factors (Q 0 , Q 1 ) from which a plurality of first partial sums (SUM1r, SUM2r) are required to be built. The method also comprises the carrying out of a second scalar multiplication (SCAL-MLTm) in order to obtain a second result ([m]P). This second multiplication provides that a plurality of second partial sums (SUM1m, SUM2m) may be built. A piece of encrypted information is obtained by processing the information (INFO) based on the results of said scalar multiplications. The method is characterized in that in order to build the second partial sums of the second scalar multiplication the same ordered factors being obtained by the generation step of the first scalar multiplication are employed.
Abstract:
An authentication method of a first module (A) by a second module (B). This method comprises the steps of:
generating, by the second module (B), a first random datum (U) to be sent to the first module (A); generating by the first module (A) a first number (v; v') starting from said first datum (U) and by means of a private key ([s]Q_A; [1/(a+s)]Q 1 ) of the first module (A); generating by the second module (B) a second number (n; n') to be compared with the first number, such as to authenticate the first module (A). Furthermore, the step of generating the second number (n; n') is performed starting from public parameters and is independent of the step of generating the first number.