diff options
Diffstat (limited to 'openssl-1.1.0h/crypto/bn/bn_mod.c')
| -rw-r--r-- | openssl-1.1.0h/crypto/bn/bn_mod.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/openssl-1.1.0h/crypto/bn/bn_mod.c b/openssl-1.1.0h/crypto/bn/bn_mod.c new file mode 100644 index 0000000..13b583f --- /dev/null +++ b/openssl-1.1.0h/crypto/bn/bn_mod.c @@ -0,0 +1,201 @@ +/* + * Copyright 1998-2016 The OpenSSL Project Authors. All Rights Reserved. + * + * Licensed under the OpenSSL license (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html + */ + +#include "internal/cryptlib.h" +#include "bn_lcl.h" + +int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) +{ + /* + * like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d| + * always holds) + */ + + if (!(BN_mod(r, m, d, ctx))) + return 0; + if (!r->neg) + return 1; + /* now -|d| < r < 0, so we have to set r := r + |d| */ + return (d->neg ? BN_sub : BN_add) (r, r, d); +} + +int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, + BN_CTX *ctx) +{ + if (!BN_add(r, a, b)) + return 0; + return BN_nnmod(r, r, m, ctx); +} + +/* + * BN_mod_add variant that may be used if both a and b are non-negative and + * less than m + */ +int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + if (!BN_uadd(r, a, b)) + return 0; + if (BN_ucmp(r, m) >= 0) + return BN_usub(r, r, m); + return 1; +} + +int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, + BN_CTX *ctx) +{ + if (!BN_sub(r, a, b)) + return 0; + return BN_nnmod(r, r, m, ctx); +} + +/* + * BN_mod_sub variant that may be used if both a and b are non-negative and + * less than m + */ +int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + if (!BN_sub(r, a, b)) + return 0; + if (r->neg) + return BN_add(r, r, m); + return 1; +} + +/* slow but works */ +int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, + BN_CTX *ctx) +{ + BIGNUM *t; + int ret = 0; + + bn_check_top(a); + bn_check_top(b); + bn_check_top(m); + + BN_CTX_start(ctx); + if ((t = BN_CTX_get(ctx)) == NULL) + goto err; + if (a == b) { + if (!BN_sqr(t, a, ctx)) + goto err; + } else { + if (!BN_mul(t, a, b, ctx)) + goto err; + } + if (!BN_nnmod(r, t, m, ctx)) + goto err; + bn_check_top(r); + ret = 1; + err: + BN_CTX_end(ctx); + return (ret); +} + +int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) +{ + if (!BN_sqr(r, a, ctx)) + return 0; + /* r->neg == 0, thus we don't need BN_nnmod */ + return BN_mod(r, r, m, ctx); +} + +int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) +{ + if (!BN_lshift1(r, a)) + return 0; + bn_check_top(r); + return BN_nnmod(r, r, m, ctx); +} + +/* + * BN_mod_lshift1 variant that may be used if a is non-negative and less than + * m + */ +int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m) +{ + if (!BN_lshift1(r, a)) + return 0; + bn_check_top(r); + if (BN_cmp(r, m) >= 0) + return BN_sub(r, r, m); + return 1; +} + +int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, + BN_CTX *ctx) +{ + BIGNUM *abs_m = NULL; + int ret; + + if (!BN_nnmod(r, a, m, ctx)) + return 0; + + if (m->neg) { + abs_m = BN_dup(m); + if (abs_m == NULL) + return 0; + abs_m->neg = 0; + } + + ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m)); + bn_check_top(r); + + BN_free(abs_m); + return ret; +} + +/* + * BN_mod_lshift variant that may be used if a is non-negative and less than + * m + */ +int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m) +{ + if (r != a) { + if (BN_copy(r, a) == NULL) + return 0; + } + + while (n > 0) { + int max_shift; + + /* 0 < r < m */ + max_shift = BN_num_bits(m) - BN_num_bits(r); + /* max_shift >= 0 */ + + if (max_shift < 0) { + BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED); + return 0; + } + + if (max_shift > n) + max_shift = n; + + if (max_shift) { + if (!BN_lshift(r, r, max_shift)) + return 0; + n -= max_shift; + } else { + if (!BN_lshift1(r, r)) + return 0; + --n; + } + + /* BN_num_bits(r) <= BN_num_bits(m) */ + + if (BN_cmp(r, m) >= 0) { + if (!BN_sub(r, r, m)) + return 0; + } + } + bn_check_top(r); + + return 1; +} |