Mercurial > dropbear
diff libtommath/bn_fast_mp_invmod.c @ 1655:f52919ffd3b1
update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
* make key-generation compliant to FIPS 186.4
* fix includes in tommath_class.h
* update fuzzcorpus instead of error-out
* fixup fuzzing make-targets
* update Makefile.in
* apply necessary patches to ltm sources
* clean-up not required ltm files
* update to vanilla ltm 1.1.0
this already only contains the required files
* remove set/get double
author | Steffen Jaeckel <s_jaeckel@gmx.de> |
---|---|
date | Mon, 16 Sep 2019 15:50:38 +0200 |
parents | 8bba51a55704 |
children |
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--- a/libtommath/bn_fast_mp_invmod.c Wed May 15 21:59:45 2019 +0800 +++ b/libtommath/bn_fast_mp_invmod.c Mon Sep 16 15:50:38 2019 +0200 @@ -1,4 +1,4 @@ -#include <tommath_private.h> +#include "tommath_private.h" #ifdef BN_FAST_MP_INVMOD_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * @@ -9,140 +9,152 @@ * 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://libtom.org + * SPDX-License-Identifier: Unlicense */ -/* computes the modular inverse via binary extended euclidean algorithm, - * that is c = 1/a mod b +/* computes the modular inverse via binary extended euclidean algorithm, + * that is c = 1/a mod b * - * Based on slow invmod except this is optimized for the case where b is + * Based on slow invmod except this is optimized for the case where b is * odd as per HAC Note 14.64 on pp. 610 */ -int fast_mp_invmod (mp_int * a, mp_int * b, mp_int * c) +int fast_mp_invmod(const mp_int *a, const mp_int *b, mp_int *c) { - mp_int x, y, u, v, B, D; - int res, neg; + mp_int x, y, u, v, B, D; + int res, neg; + + /* 2. [modified] b must be odd */ + if (mp_iseven(b) == MP_YES) { + return MP_VAL; + } - /* 2. [modified] b must be odd */ - if (mp_iseven (b) == MP_YES) { - return MP_VAL; - } + /* init all our temps */ + if ((res = mp_init_multi(&x, &y, &u, &v, &B, &D, NULL)) != MP_OKAY) { + return res; + } - /* init all our temps */ - if ((res = mp_init_multi(&x, &y, &u, &v, &B, &D, NULL)) != MP_OKAY) { - return res; - } + /* x == modulus, y == value to invert */ + if ((res = mp_copy(b, &x)) != MP_OKAY) { + goto LBL_ERR; + } - /* x == modulus, y == value to invert */ - if ((res = mp_copy (b, &x)) != MP_OKAY) { - goto LBL_ERR; - } + /* we need y = |a| */ + if ((res = mp_mod(a, b, &y)) != MP_OKAY) { + goto LBL_ERR; + } - /* we need y = |a| */ - if ((res = mp_mod (a, b, &y)) != MP_OKAY) { - goto LBL_ERR; - } + /* if one of x,y is zero return an error! */ + if ((mp_iszero(&x) == MP_YES) || (mp_iszero(&y) == MP_YES)) { + res = MP_VAL; + goto LBL_ERR; + } - /* 3. u=x, v=y, A=1, B=0, C=0,D=1 */ - if ((res = mp_copy (&x, &u)) != MP_OKAY) { - goto LBL_ERR; - } - if ((res = mp_copy (&y, &v)) != MP_OKAY) { - goto LBL_ERR; - } - mp_set (&D, 1); + /* 3. u=x, v=y, A=1, B=0, C=0,D=1 */ + if ((res = mp_copy(&x, &u)) != MP_OKAY) { + goto LBL_ERR; + } + if ((res = mp_copy(&y, &v)) != MP_OKAY) { + goto LBL_ERR; + } + mp_set(&D, 1uL); top: - /* 4. while u is even do */ - while (mp_iseven (&u) == MP_YES) { - /* 4.1 u = u/2 */ - if ((res = mp_div_2 (&u, &u)) != MP_OKAY) { - goto LBL_ERR; - } - /* 4.2 if B is odd then */ - if (mp_isodd (&B) == MP_YES) { - if ((res = mp_sub (&B, &x, &B)) != MP_OKAY) { - goto LBL_ERR; + /* 4. while u is even do */ + while (mp_iseven(&u) == MP_YES) { + /* 4.1 u = u/2 */ + if ((res = mp_div_2(&u, &u)) != MP_OKAY) { + goto LBL_ERR; } - } - /* B = B/2 */ - if ((res = mp_div_2 (&B, &B)) != MP_OKAY) { - goto LBL_ERR; - } - } + /* 4.2 if B is odd then */ + if (mp_isodd(&B) == MP_YES) { + if ((res = mp_sub(&B, &x, &B)) != MP_OKAY) { + goto LBL_ERR; + } + } + /* B = B/2 */ + if ((res = mp_div_2(&B, &B)) != MP_OKAY) { + goto LBL_ERR; + } + } - /* 5. while v is even do */ - while (mp_iseven (&v) == MP_YES) { - /* 5.1 v = v/2 */ - if ((res = mp_div_2 (&v, &v)) != MP_OKAY) { - goto LBL_ERR; - } - /* 5.2 if D is odd then */ - if (mp_isodd (&D) == MP_YES) { - /* D = (D-x)/2 */ - if ((res = mp_sub (&D, &x, &D)) != MP_OKAY) { - goto LBL_ERR; + /* 5. while v is even do */ + while (mp_iseven(&v) == MP_YES) { + /* 5.1 v = v/2 */ + if ((res = mp_div_2(&v, &v)) != MP_OKAY) { + goto LBL_ERR; + } + /* 5.2 if D is odd then */ + if (mp_isodd(&D) == MP_YES) { + /* D = (D-x)/2 */ + if ((res = mp_sub(&D, &x, &D)) != MP_OKAY) { + goto LBL_ERR; + } + } + /* D = D/2 */ + if ((res = mp_div_2(&D, &D)) != MP_OKAY) { + goto LBL_ERR; + } + } + + /* 6. if u >= v then */ + if (mp_cmp(&u, &v) != MP_LT) { + /* u = u - v, B = B - D */ + if ((res = mp_sub(&u, &v, &u)) != MP_OKAY) { + goto LBL_ERR; } - } - /* D = D/2 */ - if ((res = mp_div_2 (&D, &D)) != MP_OKAY) { - goto LBL_ERR; - } - } + + if ((res = mp_sub(&B, &D, &B)) != MP_OKAY) { + goto LBL_ERR; + } + } else { + /* v - v - u, D = D - B */ + if ((res = mp_sub(&v, &u, &v)) != MP_OKAY) { + goto LBL_ERR; + } - /* 6. if u >= v then */ - if (mp_cmp (&u, &v) != MP_LT) { - /* u = u - v, B = B - D */ - if ((res = mp_sub (&u, &v, &u)) != MP_OKAY) { + if ((res = mp_sub(&D, &B, &D)) != MP_OKAY) { + goto LBL_ERR; + } + } + + /* if not zero goto step 4 */ + if (mp_iszero(&u) == MP_NO) { + goto top; + } + + /* now a = C, b = D, gcd == g*v */ + + /* if v != 1 then there is no inverse */ + if (mp_cmp_d(&v, 1uL) != MP_EQ) { + res = MP_VAL; goto LBL_ERR; - } + } - if ((res = mp_sub (&B, &D, &B)) != MP_OKAY) { - goto LBL_ERR; - } - } else { - /* v - v - u, D = D - B */ - if ((res = mp_sub (&v, &u, &v)) != MP_OKAY) { - goto LBL_ERR; - } - - if ((res = mp_sub (&D, &B, &D)) != MP_OKAY) { - goto LBL_ERR; - } - } - - /* if not zero goto step 4 */ - if (mp_iszero (&u) == MP_NO) { - goto top; - } + /* b is now the inverse */ + neg = a->sign; + while (D.sign == MP_NEG) { + if ((res = mp_add(&D, b, &D)) != MP_OKAY) { + goto LBL_ERR; + } + } - /* now a = C, b = D, gcd == g*v */ - - /* if v != 1 then there is no inverse */ - if (mp_cmp_d (&v, 1) != MP_EQ) { - res = MP_VAL; - goto LBL_ERR; - } + /* too big */ + while (mp_cmp_mag(&D, b) != MP_LT) { + if ((res = mp_sub(&D, b, &D)) != MP_OKAY) { + goto LBL_ERR; + } + } - /* b is now the inverse */ - neg = a->sign; - while (D.sign == MP_NEG) { - if ((res = mp_add (&D, b, &D)) != MP_OKAY) { - goto LBL_ERR; - } - } - mp_exch (&D, c); - c->sign = neg; - res = MP_OKAY; + mp_exch(&D, c); + c->sign = neg; + res = MP_OKAY; -LBL_ERR:mp_clear_multi (&x, &y, &u, &v, &B, &D, NULL); - return res; +LBL_ERR: + mp_clear_multi(&x, &y, &u, &v, &B, &D, NULL); + return res; } #endif -/* ref: $Format:%D$ */ -/* git commit: $Format:%H$ */ -/* commit time: $Format:%ai$ */ +/* ref: HEAD -> master, tag: v1.1.0 */ +/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ +/* commit time: 2019-01-28 20:32:32 +0100 */