diff options
Diffstat (limited to 'openssl-1.1.0h/crypto/bn/bn_mont.c')
| -rw-r--r-- | openssl-1.1.0h/crypto/bn/bn_mont.c | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/openssl-1.1.0h/crypto/bn/bn_mont.c b/openssl-1.1.0h/crypto/bn/bn_mont.c new file mode 100644 index 0000000..faef581 --- /dev/null +++ b/openssl-1.1.0h/crypto/bn/bn_mont.c @@ -0,0 +1,422 @@ +/* + * Copyright 1995-2018 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 + */ + +/* + * Details about Montgomery multiplication algorithms can be found at + * http://security.ece.orst.edu/publications.html, e.g. + * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and + * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf + */ + +#include "internal/cryptlib.h" +#include "bn_lcl.h" + +#define MONT_WORD /* use the faster word-based algorithm */ + +#ifdef MONT_WORD +static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont); +#endif + +int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, + BN_MONT_CTX *mont, BN_CTX *ctx) +{ + BIGNUM *tmp; + int ret = 0; +#if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD) + int num = mont->N.top; + + if (num > 1 && a->top == num && b->top == num) { + if (bn_wexpand(r, num) == NULL) + return (0); + if (bn_mul_mont(r->d, a->d, b->d, mont->N.d, mont->n0, num)) { + r->neg = a->neg ^ b->neg; + r->top = num; + bn_correct_top(r); + return (1); + } + } +#endif + + BN_CTX_start(ctx); + tmp = BN_CTX_get(ctx); + if (tmp == NULL) + goto err; + + bn_check_top(tmp); + if (a == b) { + if (!BN_sqr(tmp, a, ctx)) + goto err; + } else { + if (!BN_mul(tmp, a, b, ctx)) + goto err; + } + /* reduce from aRR to aR */ +#ifdef MONT_WORD + if (!BN_from_montgomery_word(r, tmp, mont)) + goto err; +#else + if (!BN_from_montgomery(r, tmp, mont, ctx)) + goto err; +#endif + bn_check_top(r); + ret = 1; + err: + BN_CTX_end(ctx); + return (ret); +} + +#ifdef MONT_WORD +static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) +{ + BIGNUM *n; + BN_ULONG *ap, *np, *rp, n0, v, carry; + int nl, max, i; + + n = &(mont->N); + nl = n->top; + if (nl == 0) { + ret->top = 0; + return (1); + } + + max = (2 * nl); /* carry is stored separately */ + if (bn_wexpand(r, max) == NULL) + return (0); + + r->neg ^= n->neg; + np = n->d; + rp = r->d; + + /* clear the top words of T */ + i = max - r->top; + if (i) + memset(&rp[r->top], 0, sizeof(*rp) * i); + + r->top = max; + n0 = mont->n0[0]; + + /* + * Add multiples of |n| to |r| until R = 2^(nl * BN_BITS2) divides it. On + * input, we had |r| < |n| * R, so now |r| < 2 * |n| * R. Note that |r| + * includes |carry| which is stored separately. + */ + for (carry = 0, i = 0; i < nl; i++, rp++) { + v = bn_mul_add_words(rp, np, nl, (rp[0] * n0) & BN_MASK2); + v = (v + carry + rp[nl]) & BN_MASK2; + carry |= (v != rp[nl]); + carry &= (v <= rp[nl]); + rp[nl] = v; + } + + if (bn_wexpand(ret, nl) == NULL) + return (0); + ret->top = nl; + ret->neg = r->neg; + + rp = ret->d; + + /* + * Shift |nl| words to divide by R. We have |ap| < 2 * |n|. Note that |ap| + * includes |carry| which is stored separately. + */ + ap = &(r->d[nl]); + + /* + * |v| is one if |ap| - |np| underflowed or zero if it did not. Note |v| + * cannot be -1. That would imply the subtraction did not fit in |nl| words, + * and we know at most one subtraction is needed. + */ + v = bn_sub_words(rp, ap, np, nl) - carry; + v = 0 - v; + for (i = 0; i < nl; i++) { + rp[i] = (v & ap[i]) | (~v & rp[i]); + ap[i] = 0; + } + bn_correct_top(r); + bn_correct_top(ret); + bn_check_top(ret); + + return (1); +} +#endif /* MONT_WORD */ + +int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont, + BN_CTX *ctx) +{ + int retn = 0; +#ifdef MONT_WORD + BIGNUM *t; + + BN_CTX_start(ctx); + if ((t = BN_CTX_get(ctx)) && BN_copy(t, a)) + retn = BN_from_montgomery_word(ret, t, mont); + BN_CTX_end(ctx); +#else /* !MONT_WORD */ + BIGNUM *t1, *t2; + + BN_CTX_start(ctx); + t1 = BN_CTX_get(ctx); + t2 = BN_CTX_get(ctx); + if (t1 == NULL || t2 == NULL) + goto err; + + if (!BN_copy(t1, a)) + goto err; + BN_mask_bits(t1, mont->ri); + + if (!BN_mul(t2, t1, &mont->Ni, ctx)) + goto err; + BN_mask_bits(t2, mont->ri); + + if (!BN_mul(t1, t2, &mont->N, ctx)) + goto err; + if (!BN_add(t2, a, t1)) + goto err; + if (!BN_rshift(ret, t2, mont->ri)) + goto err; + + if (BN_ucmp(ret, &(mont->N)) >= 0) { + if (!BN_usub(ret, ret, &(mont->N))) + goto err; + } + retn = 1; + bn_check_top(ret); + err: + BN_CTX_end(ctx); +#endif /* MONT_WORD */ + return (retn); +} + +BN_MONT_CTX *BN_MONT_CTX_new(void) +{ + BN_MONT_CTX *ret; + + if ((ret = OPENSSL_malloc(sizeof(*ret))) == NULL) + return (NULL); + + BN_MONT_CTX_init(ret); + ret->flags = BN_FLG_MALLOCED; + return (ret); +} + +void BN_MONT_CTX_init(BN_MONT_CTX *ctx) +{ + ctx->ri = 0; + bn_init(&(ctx->RR)); + bn_init(&(ctx->N)); + bn_init(&(ctx->Ni)); + ctx->n0[0] = ctx->n0[1] = 0; + ctx->flags = 0; +} + +void BN_MONT_CTX_free(BN_MONT_CTX *mont) +{ + if (mont == NULL) + return; + + BN_clear_free(&(mont->RR)); + BN_clear_free(&(mont->N)); + BN_clear_free(&(mont->Ni)); + if (mont->flags & BN_FLG_MALLOCED) + OPENSSL_free(mont); +} + +int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx) +{ + int ret = 0; + BIGNUM *Ri, *R; + + if (BN_is_zero(mod)) + return 0; + + BN_CTX_start(ctx); + if ((Ri = BN_CTX_get(ctx)) == NULL) + goto err; + R = &(mont->RR); /* grab RR as a temp */ + if (!BN_copy(&(mont->N), mod)) + goto err; /* Set N */ + if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0) + BN_set_flags(&(mont->N), BN_FLG_CONSTTIME); + mont->N.neg = 0; + +#ifdef MONT_WORD + { + BIGNUM tmod; + BN_ULONG buf[2]; + + bn_init(&tmod); + tmod.d = buf; + tmod.dmax = 2; + tmod.neg = 0; + + if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0) + BN_set_flags(&tmod, BN_FLG_CONSTTIME); + + mont->ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2; + +# if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32) + /* + * Only certain BN_BITS2<=32 platforms actually make use of n0[1], + * and we could use the #else case (with a shorter R value) for the + * others. However, currently only the assembler files do know which + * is which. + */ + + BN_zero(R); + if (!(BN_set_bit(R, 2 * BN_BITS2))) + goto err; + + tmod.top = 0; + if ((buf[0] = mod->d[0])) + tmod.top = 1; + if ((buf[1] = mod->top > 1 ? mod->d[1] : 0)) + tmod.top = 2; + + if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL) + goto err; + if (!BN_lshift(Ri, Ri, 2 * BN_BITS2)) + goto err; /* R*Ri */ + if (!BN_is_zero(Ri)) { + if (!BN_sub_word(Ri, 1)) + goto err; + } else { /* if N mod word size == 1 */ + + if (bn_expand(Ri, (int)sizeof(BN_ULONG) * 2) == NULL) + goto err; + /* Ri-- (mod double word size) */ + Ri->neg = 0; + Ri->d[0] = BN_MASK2; + Ri->d[1] = BN_MASK2; + Ri->top = 2; + } + if (!BN_div(Ri, NULL, Ri, &tmod, ctx)) + goto err; + /* + * Ni = (R*Ri-1)/N, keep only couple of least significant words: + */ + mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; + mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0; +# else + BN_zero(R); + if (!(BN_set_bit(R, BN_BITS2))) + goto err; /* R */ + + buf[0] = mod->d[0]; /* tmod = N mod word size */ + buf[1] = 0; + tmod.top = buf[0] != 0 ? 1 : 0; + /* Ri = R^-1 mod N */ + if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL) + goto err; + if (!BN_lshift(Ri, Ri, BN_BITS2)) + goto err; /* R*Ri */ + if (!BN_is_zero(Ri)) { + if (!BN_sub_word(Ri, 1)) + goto err; + } else { /* if N mod word size == 1 */ + + if (!BN_set_word(Ri, BN_MASK2)) + goto err; /* Ri-- (mod word size) */ + } + if (!BN_div(Ri, NULL, Ri, &tmod, ctx)) + goto err; + /* + * Ni = (R*Ri-1)/N, keep only least significant word: + */ + mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; + mont->n0[1] = 0; +# endif + } +#else /* !MONT_WORD */ + { /* bignum version */ + mont->ri = BN_num_bits(&mont->N); + BN_zero(R); + if (!BN_set_bit(R, mont->ri)) + goto err; /* R = 2^ri */ + /* Ri = R^-1 mod N */ + if ((BN_mod_inverse(Ri, R, &mont->N, ctx)) == NULL) + goto err; + if (!BN_lshift(Ri, Ri, mont->ri)) + goto err; /* R*Ri */ + if (!BN_sub_word(Ri, 1)) + goto err; + /* + * Ni = (R*Ri-1) / N + */ + if (!BN_div(&(mont->Ni), NULL, Ri, &mont->N, ctx)) + goto err; + } +#endif + + /* setup RR for conversions */ + BN_zero(&(mont->RR)); + if (!BN_set_bit(&(mont->RR), mont->ri * 2)) + goto err; + if (!BN_mod(&(mont->RR), &(mont->RR), &(mont->N), ctx)) + goto err; + + ret = 1; + err: + BN_CTX_end(ctx); + return ret; +} + +BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from) +{ + if (to == from) + return (to); + + if (!BN_copy(&(to->RR), &(from->RR))) + return NULL; + if (!BN_copy(&(to->N), &(from->N))) + return NULL; + if (!BN_copy(&(to->Ni), &(from->Ni))) + return NULL; + to->ri = from->ri; + to->n0[0] = from->n0[0]; + to->n0[1] = from->n0[1]; + return (to); +} + +BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, CRYPTO_RWLOCK *lock, + const BIGNUM *mod, BN_CTX *ctx) +{ + BN_MONT_CTX *ret; + + CRYPTO_THREAD_read_lock(lock); + ret = *pmont; + CRYPTO_THREAD_unlock(lock); + if (ret) + return ret; + + /* + * We don't want to serialise globally while doing our lazy-init math in + * BN_MONT_CTX_set. That punishes threads that are doing independent + * things. Instead, punish the case where more than one thread tries to + * lazy-init the same 'pmont', by having each do the lazy-init math work + * independently and only use the one from the thread that wins the race + * (the losers throw away the work they've done). + */ + ret = BN_MONT_CTX_new(); + if (ret == NULL) + return NULL; + if (!BN_MONT_CTX_set(ret, mod, ctx)) { + BN_MONT_CTX_free(ret); + return NULL; + } + + /* The locked compare-and-set, after the local work is done. */ + CRYPTO_THREAD_write_lock(lock); + if (*pmont) { + BN_MONT_CTX_free(ret); + ret = *pmont; + } else + *pmont = ret; + CRYPTO_THREAD_unlock(lock); + return ret; +} |