diff options
Diffstat (limited to 'openssl-1.1.0h/crypto/bn/bn_exp2.c')
| -rw-r--r-- | openssl-1.1.0h/crypto/bn/bn_exp2.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/openssl-1.1.0h/crypto/bn/bn_exp2.c b/openssl-1.1.0h/crypto/bn/bn_exp2.c new file mode 100644 index 0000000..5141c21 --- /dev/null +++ b/openssl-1.1.0h/crypto/bn/bn_exp2.c @@ -0,0 +1,201 @@ +/* + * Copyright 1995-2016 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 <stdio.h> +#include "internal/cryptlib.h" +#include "bn_lcl.h" + +#define TABLE_SIZE 32 + +int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1, + const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m, + BN_CTX *ctx, BN_MONT_CTX *in_mont) +{ + int i, j, bits, b, bits1, bits2, ret = + 0, wpos1, wpos2, window1, window2, wvalue1, wvalue2; + int r_is_one = 1; + BIGNUM *d, *r; + const BIGNUM *a_mod_m; + /* Tables of variables obtained from 'ctx' */ + BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE]; + BN_MONT_CTX *mont = NULL; + + bn_check_top(a1); + bn_check_top(p1); + bn_check_top(a2); + bn_check_top(p2); + bn_check_top(m); + + if (!(m->d[0] & 1)) { + BNerr(BN_F_BN_MOD_EXP2_MONT, BN_R_CALLED_WITH_EVEN_MODULUS); + return (0); + } + bits1 = BN_num_bits(p1); + bits2 = BN_num_bits(p2); + if ((bits1 == 0) && (bits2 == 0)) { + ret = BN_one(rr); + return ret; + } + + bits = (bits1 > bits2) ? bits1 : bits2; + + BN_CTX_start(ctx); + d = BN_CTX_get(ctx); + r = BN_CTX_get(ctx); + val1[0] = BN_CTX_get(ctx); + val2[0] = BN_CTX_get(ctx); + if (!d || !r || !val1[0] || !val2[0]) + goto err; + + if (in_mont != NULL) + mont = in_mont; + else { + if ((mont = BN_MONT_CTX_new()) == NULL) + goto err; + if (!BN_MONT_CTX_set(mont, m, ctx)) + goto err; + } + + window1 = BN_window_bits_for_exponent_size(bits1); + window2 = BN_window_bits_for_exponent_size(bits2); + + /* + * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1) + */ + if (a1->neg || BN_ucmp(a1, m) >= 0) { + if (!BN_mod(val1[0], a1, m, ctx)) + goto err; + a_mod_m = val1[0]; + } else + a_mod_m = a1; + if (BN_is_zero(a_mod_m)) { + BN_zero(rr); + ret = 1; + goto err; + } + + if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx)) + goto err; + if (window1 > 1) { + if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx)) + goto err; + + j = 1 << (window1 - 1); + for (i = 1; i < j; i++) { + if (((val1[i] = BN_CTX_get(ctx)) == NULL) || + !BN_mod_mul_montgomery(val1[i], val1[i - 1], d, mont, ctx)) + goto err; + } + } + + /* + * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1) + */ + if (a2->neg || BN_ucmp(a2, m) >= 0) { + if (!BN_mod(val2[0], a2, m, ctx)) + goto err; + a_mod_m = val2[0]; + } else + a_mod_m = a2; + if (BN_is_zero(a_mod_m)) { + BN_zero(rr); + ret = 1; + goto err; + } + if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx)) + goto err; + if (window2 > 1) { + if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx)) + goto err; + + j = 1 << (window2 - 1); + for (i = 1; i < j; i++) { + if (((val2[i] = BN_CTX_get(ctx)) == NULL) || + !BN_mod_mul_montgomery(val2[i], val2[i - 1], d, mont, ctx)) + goto err; + } + } + + /* Now compute the power product, using independent windows. */ + r_is_one = 1; + wvalue1 = 0; /* The 'value' of the first window */ + wvalue2 = 0; /* The 'value' of the second window */ + wpos1 = 0; /* If wvalue1 > 0, the bottom bit of the + * first window */ + wpos2 = 0; /* If wvalue2 > 0, the bottom bit of the + * second window */ + + if (!BN_to_montgomery(r, BN_value_one(), mont, ctx)) + goto err; + for (b = bits - 1; b >= 0; b--) { + if (!r_is_one) { + if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) + goto err; + } + + if (!wvalue1) + if (BN_is_bit_set(p1, b)) { + /* + * consider bits b-window1+1 .. b for this window + */ + i = b - window1 + 1; + while (!BN_is_bit_set(p1, i)) /* works for i<0 */ + i++; + wpos1 = i; + wvalue1 = 1; + for (i = b - 1; i >= wpos1; i--) { + wvalue1 <<= 1; + if (BN_is_bit_set(p1, i)) + wvalue1++; + } + } + + if (!wvalue2) + if (BN_is_bit_set(p2, b)) { + /* + * consider bits b-window2+1 .. b for this window + */ + i = b - window2 + 1; + while (!BN_is_bit_set(p2, i)) + i++; + wpos2 = i; + wvalue2 = 1; + for (i = b - 1; i >= wpos2; i--) { + wvalue2 <<= 1; + if (BN_is_bit_set(p2, i)) + wvalue2++; + } + } + + if (wvalue1 && b == wpos1) { + /* wvalue1 is odd and < 2^window1 */ + if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1], mont, ctx)) + goto err; + wvalue1 = 0; + r_is_one = 0; + } + + if (wvalue2 && b == wpos2) { + /* wvalue2 is odd and < 2^window2 */ + if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1], mont, ctx)) + goto err; + wvalue2 = 0; + r_is_one = 0; + } + } + if (!BN_from_montgomery(rr, r, mont, ctx)) + goto err; + ret = 1; + err: + if (in_mont == NULL) + BN_MONT_CTX_free(mont); + BN_CTX_end(ctx); + bn_check_top(rr); + return (ret); +} |