diff options
Diffstat (limited to 'freebsd/crypto/openssl/crypto/bn/bn_mod.c')
| -rw-r--r-- | freebsd/crypto/openssl/crypto/bn/bn_mod.c | 69 |
1 files changed, 62 insertions, 7 deletions
diff --git a/freebsd/crypto/openssl/crypto/bn/bn_mod.c b/freebsd/crypto/openssl/crypto/bn/bn_mod.c index e79d8209..94762168 100644 --- a/freebsd/crypto/openssl/crypto/bn/bn_mod.c +++ b/freebsd/crypto/openssl/crypto/bn/bn_mod.c @@ -6,7 +6,7 @@ * for the OpenSSL project. */ /* ==================================================================== - * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved. + * Copyright (c) 1998-2018 The OpenSSL Project. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -151,18 +151,73 @@ int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, /* * BN_mod_add variant that may be used if both a and b are non-negative and - * less than m + * less than m. The original algorithm was + * + * if (!BN_uadd(r, a, b)) + * return 0; + * if (BN_ucmp(r, m) >= 0) + * return BN_usub(r, r, m); + * + * which is replaced with addition, subtracting modulus, and conditional + * move depending on whether or not subtraction borrowed. */ -int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, - const BIGNUM *m) +int bn_mod_add_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) { - if (!BN_uadd(r, a, b)) + size_t i, ai, bi, mtop = m->top; + BN_ULONG storage[1024 / BN_BITS2]; + BN_ULONG carry, temp, mask, *rp, *tp = storage; + const BN_ULONG *ap, *bp; + + if (bn_wexpand(r, m->top) == NULL) return 0; - if (BN_ucmp(r, m) >= 0) - return BN_usub(r, r, m); + + if (mtop > sizeof(storage) / sizeof(storage[0]) + && (tp = OPENSSL_malloc(mtop * sizeof(BN_ULONG))) == NULL) + return 0; + + ap = a->d != NULL ? a->d : tp; + bp = b->d != NULL ? b->d : tp; + + for (i = 0, ai = 0, bi = 0, carry = 0; i < mtop;) { + mask = (BN_ULONG)0 - ((i - a->top) >> (8 * sizeof(i) - 1)); + temp = ((ap[ai] & mask) + carry) & BN_MASK2; + carry = (temp < carry); + + mask = (BN_ULONG)0 - ((i - b->top) >> (8 * sizeof(i) - 1)); + tp[i] = ((bp[bi] & mask) + temp) & BN_MASK2; + carry += (tp[i] < temp); + + i++; + ai += (i - a->dmax) >> (8 * sizeof(i) - 1); + bi += (i - b->dmax) >> (8 * sizeof(i) - 1); + } + rp = r->d; + carry -= bn_sub_words(rp, tp, m->d, mtop); + for (i = 0; i < mtop; i++) { + rp[i] = (carry & tp[i]) | (~carry & rp[i]); + ((volatile BN_ULONG *)tp)[i] = 0; + } + r->top = mtop; + r->neg = 0; + + if (tp != storage) + OPENSSL_free(tp); + return 1; } +int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + const BIGNUM *m) +{ + int ret = bn_mod_add_fixed_top(r, a, b, m); + + if (ret) + bn_correct_top(r); + + return ret; +} + int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, BN_CTX *ctx) { |