Mercurial > dropbear
diff bn_prime_sizes_tab.c @ 145:a96ff234ff19 libtommath
propagate of fc94c38452d9fd684a8e1eb9e3a73120aac0d38f and 3e4de4cbef3d9035a7b2f0c25e9f86e297f9f6d1 from branch 'au.asn.ucc.matt.ltm-orig' to 'au.asn.ucc.matt.ltm-db'
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sun, 19 Dec 2004 15:57:19 +0000 |
parents | 22d5cf7d4b1a |
children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/bn_prime_sizes_tab.c Sun Dec 19 15:57:19 2004 +0000 @@ -0,0 +1,51 @@ +/* LibTomMath, multiple-precision integer library -- Tom St Denis + * + * LibTomMath is a library that provides multiple-precision + * integer arithmetic as well as number theoretic functionality. + * + * The library was designed directly after the MPI library by + * Michael Fromberger but has been written from scratch with + * additional optimizations in place. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, [email protected], http://math.libtomcrypt.org + */ +#include <tommath.h> + +/* this table gives the # of rabin miller trials for a prob of failure lower than 2^-96 */ +static const struct { + int k, t; +} sizes[] = { +{ 128, 28 }, +{ 256, 16 }, +{ 384, 10 }, +{ 512, 7 }, +{ 640, 6 }, +{ 768, 5 }, +{ 896, 4 }, +{ 1024, 4 }, +{ 1152, 3 }, +{ 1280, 3 }, +{ 1408, 3 }, +{ 1536, 3 }, +{ 1664, 3 }, +{ 1792, 2 } }; + +/* returns # of RM trials required for a given bit size */ +int mp_prime_rabin_miller_trials(int size) +{ + int x; + + for (x = 0; x < (int)(sizeof(sizes)/(sizeof(sizes[0]))); x++) { + if (sizes[x].k == size) { + return sizes[x].t; + } else if (sizes[x].k > size) { + return (x == 0) ? sizes[0].t : sizes[x - 1].t; + } + } + return 1; +} + +