Speeding up Elliptic Cryptosystems by Using a Signed Binary Window Method

The basic operation in elliptic cryptosystems is the computation of a multiple d?P of a point P on the elliptic curve modulo n. We propose a fast and systematic method of reducing the number of operations over elliptic curves. The proposed method is based on pre-computation to generate an adequate addition-subtraction chain for multiplier the d. By increasing the average length of zero runs in a signed binary representation of d, we can speed up the window method. Formulating the time complexity of the proposed method makes clear that the proposed method is faster than other methods. For example, for d with length 512 bits, the proposed method requires 602.6 multiplications on average. Finally, we point out. that each addition/subtraction over the elliptic curve using homogeneous coordinates can be done in 3 multiplications if parallel processing is allowed.

[1]  T. Elgamal A public key cryptosystem and a signature scheme based on discrete logarithms , 1984, CRYPTO 1984.

[2]  J. Olivos,et al.  Speeding up the computations on an elliptic curve using addition-subtraction chains , 1990, RAIRO Theor. Informatics Appl..

[3]  D. E. Knuth Seminumerical algorithm (arithmetic) , 1969 .

[4]  C. Mitchell,et al.  Minimum weight modified signed-digit representations and fast exponentiation , 1989 .

[5]  Adi Shamir,et al.  A method for obtaining digital signatures and public-key cryptosystems , 1978, CACM.

[6]  Whitfield Diffie,et al.  New Directions in Cryptography , 1976, IEEE Trans. Inf. Theory.

[7]  Donald Ervin Knuth,et al.  The Art of Computer Programming , 1968 .

[8]  H. W. Lenstra,et al.  Factoring integers with elliptic curves , 1987 .

[9]  Ernest F. Brickell,et al.  A Fast Modular Multiplication Algorithm With Application To Two Key Cryptography , 1982, CRYPTO.

[10]  Matthijs J. Coster,et al.  Addition Chain Heuristics , 1989, CRYPTO.

[11]  Joe Kilian,et al.  Almost all primes can be quickly certified , 1986, STOC '86.

[12]  Yacov Yacobi,et al.  Exponentiating Faster with Addition Chains , 1991, EUROCRYPT.

[13]  P. L. Montgomery Speeding the Pollard and elliptic curve methods of factorization , 1987 .

[14]  Ernest F. Brickell,et al.  Fast Exponentiation with Precomputation (Extended Abstract) , 1992, EUROCRYPT.

[15]  Peter J. Downey,et al.  Computing Sequences with Addition Chains , 1981, SIAM J. Comput..

[16]  N. Koblitz A Course in Number Theory and Cryptography , 1987 .

[17]  Tatsuaki Okamoto,et al.  New Public-Key Schemes Based on Elliptic Curves over the Ring Zn , 1991, CRYPTO.