Mercurial > dropbear
view libtommath/bn_s_mp_rand_jenkins.c @ 1793:f90e681b8b8c
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author | Matt Johnston <matt@ucc.asn.au> |
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date | Fri, 29 Jan 2021 21:59:12 +0800 |
parents | 1051e4eea25a |
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#include "tommath_private.h" #ifdef BN_S_MP_RAND_JENKINS_C /* LibTomMath, multiple-precision integer library -- Tom St Denis */ /* SPDX-License-Identifier: Unlicense */ /* Bob Jenkins' http://burtleburtle.net/bob/rand/smallprng.html */ /* Chosen for speed and a good "mix" */ typedef struct { uint64_t a; uint64_t b; uint64_t c; uint64_t d; } ranctx; static ranctx jenkins_x; #define rot(x,k) (((x)<<(k))|((x)>>(64-(k)))) static uint64_t s_rand_jenkins_val(void) { uint64_t e = jenkins_x.a - rot(jenkins_x.b, 7); jenkins_x.a = jenkins_x.b ^ rot(jenkins_x.c, 13); jenkins_x.b = jenkins_x.c + rot(jenkins_x.d, 37); jenkins_x.c = jenkins_x.d + e; jenkins_x.d = e + jenkins_x.a; return jenkins_x.d; } void s_mp_rand_jenkins_init(uint64_t seed) { uint64_t i; jenkins_x.a = 0xf1ea5eedULL; jenkins_x.b = jenkins_x.c = jenkins_x.d = seed; for (i = 0uLL; i < 20uLL; ++i) { (void)s_rand_jenkins_val(); } } mp_err s_mp_rand_jenkins(void *p, size_t n) { char *q = (char *)p; while (n > 0u) { int i; uint64_t x = s_rand_jenkins_val(); for (i = 0; (i < 8) && (n > 0u); ++i, --n) { *q++ = (char)(x & 0xFFuLL); x >>= 8; } } return MP_OKAY; } #endif