| /* |
| * Copyright 1995-2022 The OpenSSL Project Authors. All Rights Reserved. |
| * |
| * Licensed under the Apache License 2.0 (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 "internal/constant_time.h" |
| #include "bn_local.h" |
| |
| #include <stdlib.h> |
| #ifdef _WIN32 |
| # include <malloc.h> |
| # ifndef alloca |
| # define alloca _alloca |
| # endif |
| #elif defined(__GNUC__) |
| # ifndef alloca |
| # define alloca(s) __builtin_alloca((s)) |
| # endif |
| #elif defined(__sun) |
| # include <alloca.h> |
| #endif |
| |
| #include "rsaz_exp.h" |
| |
| #undef SPARC_T4_MONT |
| #if defined(OPENSSL_BN_ASM_MONT) && (defined(__sparc__) || defined(__sparc)) |
| # include "crypto/sparc_arch.h" |
| # define SPARC_T4_MONT |
| #endif |
| |
| /* maximum precomputation table size for *variable* sliding windows */ |
| #define TABLE_SIZE 32 |
| |
| /* this one works - simple but works */ |
| int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx) |
| { |
| int i, bits, ret = 0; |
| BIGNUM *v, *rr; |
| |
| if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(a, BN_FLG_CONSTTIME) != 0) { |
| /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */ |
| ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); |
| return 0; |
| } |
| |
| BN_CTX_start(ctx); |
| rr = ((r == a) || (r == p)) ? BN_CTX_get(ctx) : r; |
| v = BN_CTX_get(ctx); |
| if (rr == NULL || v == NULL) |
| goto err; |
| |
| if (BN_copy(v, a) == NULL) |
| goto err; |
| bits = BN_num_bits(p); |
| |
| if (BN_is_odd(p)) { |
| if (BN_copy(rr, a) == NULL) |
| goto err; |
| } else { |
| if (!BN_one(rr)) |
| goto err; |
| } |
| |
| for (i = 1; i < bits; i++) { |
| if (!BN_sqr(v, v, ctx)) |
| goto err; |
| if (BN_is_bit_set(p, i)) { |
| if (!BN_mul(rr, rr, v, ctx)) |
| goto err; |
| } |
| } |
| if (r != rr && BN_copy(r, rr) == NULL) |
| goto err; |
| |
| ret = 1; |
| err: |
| BN_CTX_end(ctx); |
| bn_check_top(r); |
| return ret; |
| } |
| |
| int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m, |
| BN_CTX *ctx) |
| { |
| int ret; |
| |
| bn_check_top(a); |
| bn_check_top(p); |
| bn_check_top(m); |
| |
| /*- |
| * For even modulus m = 2^k*m_odd, it might make sense to compute |
| * a^p mod m_odd and a^p mod 2^k separately (with Montgomery |
| * exponentiation for the odd part), using appropriate exponent |
| * reductions, and combine the results using the CRT. |
| * |
| * For now, we use Montgomery only if the modulus is odd; otherwise, |
| * exponentiation using the reciprocal-based quick remaindering |
| * algorithm is used. |
| * |
| * (Timing obtained with expspeed.c [computations a^p mod m |
| * where a, p, m are of the same length: 256, 512, 1024, 2048, |
| * 4096, 8192 bits], compared to the running time of the |
| * standard algorithm: |
| * |
| * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration] |
| * 55 .. 77 % [UltraSparc processor, but |
| * debug-solaris-sparcv8-gcc conf.] |
| * |
| * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration] |
| * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc] |
| * |
| * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont |
| * at 2048 and more bits, but at 512 and 1024 bits, it was |
| * slower even than the standard algorithm! |
| * |
| * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations] |
| * should be obtained when the new Montgomery reduction code |
| * has been integrated into OpenSSL.) |
| */ |
| |
| #define MONT_MUL_MOD |
| #define MONT_EXP_WORD |
| #define RECP_MUL_MOD |
| |
| #ifdef MONT_MUL_MOD |
| if (BN_is_odd(m)) { |
| # ifdef MONT_EXP_WORD |
| if (a->top == 1 && !a->neg |
| && (BN_get_flags(p, BN_FLG_CONSTTIME) == 0) |
| && (BN_get_flags(a, BN_FLG_CONSTTIME) == 0) |
| && (BN_get_flags(m, BN_FLG_CONSTTIME) == 0)) { |
| BN_ULONG A = a->d[0]; |
| ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL); |
| } else |
| # endif |
| ret = BN_mod_exp_mont(r, a, p, m, ctx, NULL); |
| } else |
| #endif |
| #ifdef RECP_MUL_MOD |
| { |
| ret = BN_mod_exp_recp(r, a, p, m, ctx); |
| } |
| #else |
| { |
| ret = BN_mod_exp_simple(r, a, p, m, ctx); |
| } |
| #endif |
| |
| bn_check_top(r); |
| return ret; |
| } |
| |
| int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, |
| const BIGNUM *m, BN_CTX *ctx) |
| { |
| int i, j, bits, ret = 0, wstart, wend, window, wvalue; |
| int start = 1; |
| BIGNUM *aa; |
| /* Table of variables obtained from 'ctx' */ |
| BIGNUM *val[TABLE_SIZE]; |
| BN_RECP_CTX recp; |
| |
| if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(a, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) { |
| /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */ |
| ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); |
| return 0; |
| } |
| |
| bits = BN_num_bits(p); |
| if (bits == 0) { |
| /* x**0 mod 1, or x**0 mod -1 is still zero. */ |
| if (BN_abs_is_word(m, 1)) { |
| ret = 1; |
| BN_zero(r); |
| } else { |
| ret = BN_one(r); |
| } |
| return ret; |
| } |
| |
| BN_RECP_CTX_init(&recp); |
| |
| BN_CTX_start(ctx); |
| aa = BN_CTX_get(ctx); |
| val[0] = BN_CTX_get(ctx); |
| if (val[0] == NULL) |
| goto err; |
| |
| if (m->neg) { |
| /* ignore sign of 'm' */ |
| if (!BN_copy(aa, m)) |
| goto err; |
| aa->neg = 0; |
| if (BN_RECP_CTX_set(&recp, aa, ctx) <= 0) |
| goto err; |
| } else { |
| if (BN_RECP_CTX_set(&recp, m, ctx) <= 0) |
| goto err; |
| } |
| |
| if (!BN_nnmod(val[0], a, m, ctx)) |
| goto err; /* 1 */ |
| if (BN_is_zero(val[0])) { |
| BN_zero(r); |
| ret = 1; |
| goto err; |
| } |
| |
| window = BN_window_bits_for_exponent_size(bits); |
| if (window > 1) { |
| if (!BN_mod_mul_reciprocal(aa, val[0], val[0], &recp, ctx)) |
| goto err; /* 2 */ |
| j = 1 << (window - 1); |
| for (i = 1; i < j; i++) { |
| if (((val[i] = BN_CTX_get(ctx)) == NULL) || |
| !BN_mod_mul_reciprocal(val[i], val[i - 1], aa, &recp, ctx)) |
| goto err; |
| } |
| } |
| |
| start = 1; /* This is used to avoid multiplication etc |
| * when there is only the value '1' in the |
| * buffer. */ |
| wvalue = 0; /* The 'value' of the window */ |
| wstart = bits - 1; /* The top bit of the window */ |
| wend = 0; /* The bottom bit of the window */ |
| |
| if (!BN_one(r)) |
| goto err; |
| |
| for (;;) { |
| if (BN_is_bit_set(p, wstart) == 0) { |
| if (!start) |
| if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx)) |
| goto err; |
| if (wstart == 0) |
| break; |
| wstart--; |
| continue; |
| } |
| /* |
| * We now have wstart on a 'set' bit, we now need to work out how bit |
| * a window to do. To do this we need to scan forward until the last |
| * set bit before the end of the window |
| */ |
| wvalue = 1; |
| wend = 0; |
| for (i = 1; i < window; i++) { |
| if (wstart - i < 0) |
| break; |
| if (BN_is_bit_set(p, wstart - i)) { |
| wvalue <<= (i - wend); |
| wvalue |= 1; |
| wend = i; |
| } |
| } |
| |
| /* wend is the size of the current window */ |
| j = wend + 1; |
| /* add the 'bytes above' */ |
| if (!start) |
| for (i = 0; i < j; i++) { |
| if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx)) |
| goto err; |
| } |
| |
| /* wvalue will be an odd number < 2^window */ |
| if (!BN_mod_mul_reciprocal(r, r, val[wvalue >> 1], &recp, ctx)) |
| goto err; |
| |
| /* move the 'window' down further */ |
| wstart -= wend + 1; |
| wvalue = 0; |
| start = 0; |
| if (wstart < 0) |
| break; |
| } |
| ret = 1; |
| err: |
| BN_CTX_end(ctx); |
| BN_RECP_CTX_free(&recp); |
| bn_check_top(r); |
| return ret; |
| } |
| |
| int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p, |
| const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont) |
| { |
| int i, j, bits, ret = 0, wstart, wend, window, wvalue; |
| int start = 1; |
| BIGNUM *d, *r; |
| const BIGNUM *aa; |
| /* Table of variables obtained from 'ctx' */ |
| BIGNUM *val[TABLE_SIZE]; |
| BN_MONT_CTX *mont = NULL; |
| |
| if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(a, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) { |
| return BN_mod_exp_mont_consttime(rr, a, p, m, ctx, in_mont); |
| } |
| |
| bn_check_top(a); |
| bn_check_top(p); |
| bn_check_top(m); |
| |
| if (!BN_is_odd(m)) { |
| ERR_raise(ERR_LIB_BN, BN_R_CALLED_WITH_EVEN_MODULUS); |
| return 0; |
| } |
| bits = BN_num_bits(p); |
| if (bits == 0) { |
| /* x**0 mod 1, or x**0 mod -1 is still zero. */ |
| if (BN_abs_is_word(m, 1)) { |
| ret = 1; |
| BN_zero(rr); |
| } else { |
| ret = BN_one(rr); |
| } |
| return ret; |
| } |
| |
| BN_CTX_start(ctx); |
| d = BN_CTX_get(ctx); |
| r = BN_CTX_get(ctx); |
| val[0] = BN_CTX_get(ctx); |
| if (val[0] == NULL) |
| goto err; |
| |
| /* |
| * If this is not done, things will break in the montgomery part |
| */ |
| |
| 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; |
| } |
| |
| if (a->neg || BN_ucmp(a, m) >= 0) { |
| if (!BN_nnmod(val[0], a, m, ctx)) |
| goto err; |
| aa = val[0]; |
| } else |
| aa = a; |
| if (!bn_to_mont_fixed_top(val[0], aa, mont, ctx)) |
| goto err; /* 1 */ |
| |
| window = BN_window_bits_for_exponent_size(bits); |
| if (window > 1) { |
| if (!bn_mul_mont_fixed_top(d, val[0], val[0], mont, ctx)) |
| goto err; /* 2 */ |
| j = 1 << (window - 1); |
| for (i = 1; i < j; i++) { |
| if (((val[i] = BN_CTX_get(ctx)) == NULL) || |
| !bn_mul_mont_fixed_top(val[i], val[i - 1], d, mont, ctx)) |
| goto err; |
| } |
| } |
| |
| start = 1; /* This is used to avoid multiplication etc |
| * when there is only the value '1' in the |
| * buffer. */ |
| wvalue = 0; /* The 'value' of the window */ |
| wstart = bits - 1; /* The top bit of the window */ |
| wend = 0; /* The bottom bit of the window */ |
| |
| #if 1 /* by Shay Gueron's suggestion */ |
| j = m->top; /* borrow j */ |
| if (m->d[j - 1] & (((BN_ULONG)1) << (BN_BITS2 - 1))) { |
| if (bn_wexpand(r, j) == NULL) |
| goto err; |
| /* 2^(top*BN_BITS2) - m */ |
| r->d[0] = (0 - m->d[0]) & BN_MASK2; |
| for (i = 1; i < j; i++) |
| r->d[i] = (~m->d[i]) & BN_MASK2; |
| r->top = j; |
| r->flags |= BN_FLG_FIXED_TOP; |
| } else |
| #endif |
| if (!bn_to_mont_fixed_top(r, BN_value_one(), mont, ctx)) |
| goto err; |
| for (;;) { |
| if (BN_is_bit_set(p, wstart) == 0) { |
| if (!start) { |
| if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx)) |
| goto err; |
| } |
| if (wstart == 0) |
| break; |
| wstart--; |
| continue; |
| } |
| /* |
| * We now have wstart on a 'set' bit, we now need to work out how bit |
| * a window to do. To do this we need to scan forward until the last |
| * set bit before the end of the window |
| */ |
| wvalue = 1; |
| wend = 0; |
| for (i = 1; i < window; i++) { |
| if (wstart - i < 0) |
| break; |
| if (BN_is_bit_set(p, wstart - i)) { |
| wvalue <<= (i - wend); |
| wvalue |= 1; |
| wend = i; |
| } |
| } |
| |
| /* wend is the size of the current window */ |
| j = wend + 1; |
| /* add the 'bytes above' */ |
| if (!start) |
| for (i = 0; i < j; i++) { |
| if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx)) |
| goto err; |
| } |
| |
| /* wvalue will be an odd number < 2^window */ |
| if (!bn_mul_mont_fixed_top(r, r, val[wvalue >> 1], mont, ctx)) |
| goto err; |
| |
| /* move the 'window' down further */ |
| wstart -= wend + 1; |
| wvalue = 0; |
| start = 0; |
| if (wstart < 0) |
| break; |
| } |
| /* |
| * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery |
| * removes padding [if any] and makes return value suitable for public |
| * API consumer. |
| */ |
| #if defined(SPARC_T4_MONT) |
| if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) { |
| j = mont->N.top; /* borrow j */ |
| val[0]->d[0] = 1; /* borrow val[0] */ |
| for (i = 1; i < j; i++) |
| val[0]->d[i] = 0; |
| val[0]->top = j; |
| if (!BN_mod_mul_montgomery(rr, r, val[0], mont, ctx)) |
| goto err; |
| } else |
| #endif |
| 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; |
| } |
| |
| static BN_ULONG bn_get_bits(const BIGNUM *a, int bitpos) |
| { |
| BN_ULONG ret = 0; |
| int wordpos; |
| |
| wordpos = bitpos / BN_BITS2; |
| bitpos %= BN_BITS2; |
| if (wordpos >= 0 && wordpos < a->top) { |
| ret = a->d[wordpos] & BN_MASK2; |
| if (bitpos) { |
| ret >>= bitpos; |
| if (++wordpos < a->top) |
| ret |= a->d[wordpos] << (BN_BITS2 - bitpos); |
| } |
| } |
| |
| return ret & BN_MASK2; |
| } |
| |
| /* |
| * BN_mod_exp_mont_consttime() stores the precomputed powers in a specific |
| * layout so that accessing any of these table values shows the same access |
| * pattern as far as cache lines are concerned. The following functions are |
| * used to transfer a BIGNUM from/to that table. |
| */ |
| |
| static int MOD_EXP_CTIME_COPY_TO_PREBUF(const BIGNUM *b, int top, |
| unsigned char *buf, int idx, |
| int window) |
| { |
| int i, j; |
| int width = 1 << window; |
| BN_ULONG *table = (BN_ULONG *)buf; |
| |
| if (top > b->top) |
| top = b->top; /* this works because 'buf' is explicitly |
| * zeroed */ |
| for (i = 0, j = idx; i < top; i++, j += width) { |
| table[j] = b->d[i]; |
| } |
| |
| return 1; |
| } |
| |
| static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top, |
| unsigned char *buf, int idx, |
| int window) |
| { |
| int i, j; |
| int width = 1 << window; |
| /* |
| * We declare table 'volatile' in order to discourage compiler |
| * from reordering loads from the table. Concern is that if |
| * reordered in specific manner loads might give away the |
| * information we are trying to conceal. Some would argue that |
| * compiler can reorder them anyway, but it can as well be |
| * argued that doing so would be violation of standard... |
| */ |
| volatile BN_ULONG *table = (volatile BN_ULONG *)buf; |
| |
| if (bn_wexpand(b, top) == NULL) |
| return 0; |
| |
| if (window <= 3) { |
| for (i = 0; i < top; i++, table += width) { |
| BN_ULONG acc = 0; |
| |
| for (j = 0; j < width; j++) { |
| acc |= table[j] & |
| ((BN_ULONG)0 - (constant_time_eq_int(j,idx)&1)); |
| } |
| |
| b->d[i] = acc; |
| } |
| } else { |
| int xstride = 1 << (window - 2); |
| BN_ULONG y0, y1, y2, y3; |
| |
| i = idx >> (window - 2); /* equivalent of idx / xstride */ |
| idx &= xstride - 1; /* equivalent of idx % xstride */ |
| |
| y0 = (BN_ULONG)0 - (constant_time_eq_int(i,0)&1); |
| y1 = (BN_ULONG)0 - (constant_time_eq_int(i,1)&1); |
| y2 = (BN_ULONG)0 - (constant_time_eq_int(i,2)&1); |
| y3 = (BN_ULONG)0 - (constant_time_eq_int(i,3)&1); |
| |
| for (i = 0; i < top; i++, table += width) { |
| BN_ULONG acc = 0; |
| |
| for (j = 0; j < xstride; j++) { |
| acc |= ( (table[j + 0 * xstride] & y0) | |
| (table[j + 1 * xstride] & y1) | |
| (table[j + 2 * xstride] & y2) | |
| (table[j + 3 * xstride] & y3) ) |
| & ((BN_ULONG)0 - (constant_time_eq_int(j,idx)&1)); |
| } |
| |
| b->d[i] = acc; |
| } |
| } |
| |
| b->top = top; |
| b->flags |= BN_FLG_FIXED_TOP; |
| return 1; |
| } |
| |
| /* |
| * Given a pointer value, compute the next address that is a cache line |
| * multiple. |
| */ |
| #define MOD_EXP_CTIME_ALIGN(x_) \ |
| ((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH - (((size_t)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK)))) |
| |
| /* |
| * This variant of BN_mod_exp_mont() uses fixed windows and the special |
| * precomputation memory layout to limit data-dependency to a minimum to |
| * protect secret exponents (cf. the hyper-threading timing attacks pointed |
| * out by Colin Percival, |
| * http://www.daemonology.net/hyperthreading-considered-harmful/) |
| */ |
| int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p, |
| const BIGNUM *m, BN_CTX *ctx, |
| BN_MONT_CTX *in_mont) |
| { |
| int i, bits, ret = 0, window, wvalue, wmask, window0; |
| int top; |
| BN_MONT_CTX *mont = NULL; |
| |
| int numPowers; |
| unsigned char *powerbufFree = NULL; |
| int powerbufLen = 0; |
| unsigned char *powerbuf = NULL; |
| BIGNUM tmp, am; |
| #if defined(SPARC_T4_MONT) |
| unsigned int t4 = 0; |
| #endif |
| |
| bn_check_top(a); |
| bn_check_top(p); |
| bn_check_top(m); |
| |
| if (!BN_is_odd(m)) { |
| ERR_raise(ERR_LIB_BN, BN_R_CALLED_WITH_EVEN_MODULUS); |
| return 0; |
| } |
| |
| top = m->top; |
| |
| /* |
| * Use all bits stored in |p|, rather than |BN_num_bits|, so we do not leak |
| * whether the top bits are zero. |
| */ |
| bits = p->top * BN_BITS2; |
| if (bits == 0) { |
| /* x**0 mod 1, or x**0 mod -1 is still zero. */ |
| if (BN_abs_is_word(m, 1)) { |
| ret = 1; |
| BN_zero(rr); |
| } else { |
| ret = BN_one(rr); |
| } |
| return ret; |
| } |
| |
| BN_CTX_start(ctx); |
| |
| /* |
| * Allocate a montgomery context if it was not supplied by the caller. If |
| * this is not done, things will break in the montgomery part. |
| */ |
| 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; |
| } |
| |
| if (a->neg || BN_ucmp(a, m) >= 0) { |
| BIGNUM *reduced = BN_CTX_get(ctx); |
| if (reduced == NULL |
| || !BN_nnmod(reduced, a, m, ctx)) { |
| goto err; |
| } |
| a = reduced; |
| } |
| |
| #ifdef RSAZ_ENABLED |
| /* |
| * If the size of the operands allow it, perform the optimized |
| * RSAZ exponentiation. For further information see |
| * crypto/bn/rsaz_exp.c and accompanying assembly modules. |
| */ |
| if ((16 == a->top) && (16 == p->top) && (BN_num_bits(m) == 1024) |
| && rsaz_avx2_eligible()) { |
| if (NULL == bn_wexpand(rr, 16)) |
| goto err; |
| RSAZ_1024_mod_exp_avx2(rr->d, a->d, p->d, m->d, mont->RR.d, |
| mont->n0[0]); |
| rr->top = 16; |
| rr->neg = 0; |
| bn_correct_top(rr); |
| ret = 1; |
| goto err; |
| } else if ((8 == a->top) && (8 == p->top) && (BN_num_bits(m) == 512)) { |
| if (NULL == bn_wexpand(rr, 8)) |
| goto err; |
| RSAZ_512_mod_exp(rr->d, a->d, p->d, m->d, mont->n0[0], mont->RR.d); |
| rr->top = 8; |
| rr->neg = 0; |
| bn_correct_top(rr); |
| ret = 1; |
| goto err; |
| } |
| #endif |
| |
| /* Get the window size to use with size of p. */ |
| window = BN_window_bits_for_ctime_exponent_size(bits); |
| #if defined(SPARC_T4_MONT) |
| if (window >= 5 && (top & 15) == 0 && top <= 64 && |
| (OPENSSL_sparcv9cap_P[1] & (CFR_MONTMUL | CFR_MONTSQR)) == |
| (CFR_MONTMUL | CFR_MONTSQR) && (t4 = OPENSSL_sparcv9cap_P[0])) |
| window = 5; |
| else |
| #endif |
| #if defined(OPENSSL_BN_ASM_MONT5) |
| if (window >= 5) { |
| window = 5; /* ~5% improvement for RSA2048 sign, and even |
| * for RSA4096 */ |
| /* reserve space for mont->N.d[] copy */ |
| powerbufLen += top * sizeof(mont->N.d[0]); |
| } |
| #endif |
| (void)0; |
| |
| /* |
| * Allocate a buffer large enough to hold all of the pre-computed powers |
| * of am, am itself and tmp. |
| */ |
| numPowers = 1 << window; |
| powerbufLen += sizeof(m->d[0]) * (top * numPowers + |
| ((2 * top) > |
| numPowers ? (2 * top) : numPowers)); |
| #ifdef alloca |
| if (powerbufLen < 3072) |
| powerbufFree = |
| alloca(powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH); |
| else |
| #endif |
| if ((powerbufFree = |
| OPENSSL_malloc(powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) |
| == NULL) |
| goto err; |
| |
| powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree); |
| memset(powerbuf, 0, powerbufLen); |
| |
| #ifdef alloca |
| if (powerbufLen < 3072) |
| powerbufFree = NULL; |
| #endif |
| |
| /* lay down tmp and am right after powers table */ |
| tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0]) * top * numPowers); |
| am.d = tmp.d + top; |
| tmp.top = am.top = 0; |
| tmp.dmax = am.dmax = top; |
| tmp.neg = am.neg = 0; |
| tmp.flags = am.flags = BN_FLG_STATIC_DATA; |
| |
| /* prepare a^0 in Montgomery domain */ |
| #if 1 /* by Shay Gueron's suggestion */ |
| if (m->d[top - 1] & (((BN_ULONG)1) << (BN_BITS2 - 1))) { |
| /* 2^(top*BN_BITS2) - m */ |
| tmp.d[0] = (0 - m->d[0]) & BN_MASK2; |
| for (i = 1; i < top; i++) |
| tmp.d[i] = (~m->d[i]) & BN_MASK2; |
| tmp.top = top; |
| } else |
| #endif |
| if (!bn_to_mont_fixed_top(&tmp, BN_value_one(), mont, ctx)) |
| goto err; |
| |
| /* prepare a^1 in Montgomery domain */ |
| if (!bn_to_mont_fixed_top(&am, a, mont, ctx)) |
| goto err; |
| |
| #if defined(SPARC_T4_MONT) |
| if (t4) { |
| typedef int (*bn_pwr5_mont_f) (BN_ULONG *tp, const BN_ULONG *np, |
| const BN_ULONG *n0, const void *table, |
| int power, int bits); |
| int bn_pwr5_mont_t4_8(BN_ULONG *tp, const BN_ULONG *np, |
| const BN_ULONG *n0, const void *table, |
| int power, int bits); |
| int bn_pwr5_mont_t4_16(BN_ULONG *tp, const BN_ULONG *np, |
| const BN_ULONG *n0, const void *table, |
| int power, int bits); |
| int bn_pwr5_mont_t4_24(BN_ULONG *tp, const BN_ULONG *np, |
| const BN_ULONG *n0, const void *table, |
| int power, int bits); |
| int bn_pwr5_mont_t4_32(BN_ULONG *tp, const BN_ULONG *np, |
| const BN_ULONG *n0, const void *table, |
| int power, int bits); |
| static const bn_pwr5_mont_f pwr5_funcs[4] = { |
| bn_pwr5_mont_t4_8, bn_pwr5_mont_t4_16, |
| bn_pwr5_mont_t4_24, bn_pwr5_mont_t4_32 |
| }; |
| bn_pwr5_mont_f pwr5_worker = pwr5_funcs[top / 16 - 1]; |
| |
| typedef int (*bn_mul_mont_f) (BN_ULONG *rp, const BN_ULONG *ap, |
| const void *bp, const BN_ULONG *np, |
| const BN_ULONG *n0); |
| int bn_mul_mont_t4_8(BN_ULONG *rp, const BN_ULONG *ap, const void *bp, |
| const BN_ULONG *np, const BN_ULONG *n0); |
| int bn_mul_mont_t4_16(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *bp, const BN_ULONG *np, |
| const BN_ULONG *n0); |
| int bn_mul_mont_t4_24(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *bp, const BN_ULONG *np, |
| const BN_ULONG *n0); |
| int bn_mul_mont_t4_32(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *bp, const BN_ULONG *np, |
| const BN_ULONG *n0); |
| static const bn_mul_mont_f mul_funcs[4] = { |
| bn_mul_mont_t4_8, bn_mul_mont_t4_16, |
| bn_mul_mont_t4_24, bn_mul_mont_t4_32 |
| }; |
| bn_mul_mont_f mul_worker = mul_funcs[top / 16 - 1]; |
| |
| void bn_mul_mont_vis3(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *bp, const BN_ULONG *np, |
| const BN_ULONG *n0, int num); |
| void bn_mul_mont_t4(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *bp, const BN_ULONG *np, |
| const BN_ULONG *n0, int num); |
| void bn_mul_mont_gather5_t4(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *table, const BN_ULONG *np, |
| const BN_ULONG *n0, int num, int power); |
| void bn_flip_n_scatter5_t4(const BN_ULONG *inp, size_t num, |
| void *table, size_t power); |
| void bn_gather5_t4(BN_ULONG *out, size_t num, |
| void *table, size_t power); |
| void bn_flip_t4(BN_ULONG *dst, BN_ULONG *src, size_t num); |
| |
| BN_ULONG *np = mont->N.d, *n0 = mont->n0; |
| int stride = 5 * (6 - (top / 16 - 1)); /* multiple of 5, but less |
| * than 32 */ |
| |
| /* |
| * BN_to_montgomery can contaminate words above .top [in |
| * BN_DEBUG build... |
| */ |
| for (i = am.top; i < top; i++) |
| am.d[i] = 0; |
| for (i = tmp.top; i < top; i++) |
| tmp.d[i] = 0; |
| |
| bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, 0); |
| bn_flip_n_scatter5_t4(am.d, top, powerbuf, 1); |
| if (!(*mul_worker) (tmp.d, am.d, am.d, np, n0) && |
| !(*mul_worker) (tmp.d, am.d, am.d, np, n0)) |
| bn_mul_mont_vis3(tmp.d, am.d, am.d, np, n0, top); |
| bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, 2); |
| |
| for (i = 3; i < 32; i++) { |
| /* Calculate a^i = a^(i-1) * a */ |
| if (!(*mul_worker) (tmp.d, tmp.d, am.d, np, n0) && |
| !(*mul_worker) (tmp.d, tmp.d, am.d, np, n0)) |
| bn_mul_mont_vis3(tmp.d, tmp.d, am.d, np, n0, top); |
| bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, i); |
| } |
| |
| /* switch to 64-bit domain */ |
| np = alloca(top * sizeof(BN_ULONG)); |
| top /= 2; |
| bn_flip_t4(np, mont->N.d, top); |
| |
| /* |
| * The exponent may not have a whole number of fixed-size windows. |
| * To simplify the main loop, the initial window has between 1 and |
| * full-window-size bits such that what remains is always a whole |
| * number of windows |
| */ |
| window0 = (bits - 1) % 5 + 1; |
| wmask = (1 << window0) - 1; |
| bits -= window0; |
| wvalue = bn_get_bits(p, bits) & wmask; |
| bn_gather5_t4(tmp.d, top, powerbuf, wvalue); |
| |
| /* |
| * Scan the exponent one window at a time starting from the most |
| * significant bits. |
| */ |
| while (bits > 0) { |
| if (bits < stride) |
| stride = bits; |
| bits -= stride; |
| wvalue = bn_get_bits(p, bits); |
| |
| if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride)) |
| continue; |
| /* retry once and fall back */ |
| if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride)) |
| continue; |
| |
| bits += stride - 5; |
| wvalue >>= stride - 5; |
| wvalue &= 31; |
| bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont_gather5_t4(tmp.d, tmp.d, powerbuf, np, n0, top, |
| wvalue); |
| } |
| |
| bn_flip_t4(tmp.d, tmp.d, top); |
| top *= 2; |
| /* back to 32-bit domain */ |
| tmp.top = top; |
| bn_correct_top(&tmp); |
| OPENSSL_cleanse(np, top * sizeof(BN_ULONG)); |
| } else |
| #endif |
| #if defined(OPENSSL_BN_ASM_MONT5) |
| if (window == 5 && top > 1) { |
| /* |
| * This optimization uses ideas from http://eprint.iacr.org/2011/239, |
| * specifically optimization of cache-timing attack countermeasures |
| * and pre-computation optimization. |
| */ |
| |
| /* |
| * Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as |
| * 512-bit RSA is hardly relevant, we omit it to spare size... |
| */ |
| void bn_mul_mont_gather5(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *table, const BN_ULONG *np, |
| const BN_ULONG *n0, int num, int power); |
| void bn_scatter5(const BN_ULONG *inp, size_t num, |
| void *table, size_t power); |
| void bn_gather5(BN_ULONG *out, size_t num, void *table, size_t power); |
| void bn_power5(BN_ULONG *rp, const BN_ULONG *ap, |
| const void *table, const BN_ULONG *np, |
| const BN_ULONG *n0, int num, int power); |
| int bn_get_bits5(const BN_ULONG *ap, int off); |
| int bn_from_montgomery(BN_ULONG *rp, const BN_ULONG *ap, |
| const BN_ULONG *not_used, const BN_ULONG *np, |
| const BN_ULONG *n0, int num); |
| |
| BN_ULONG *n0 = mont->n0, *np; |
| |
| /* |
| * BN_to_montgomery can contaminate words above .top [in |
| * BN_DEBUG build... |
| */ |
| for (i = am.top; i < top; i++) |
| am.d[i] = 0; |
| for (i = tmp.top; i < top; i++) |
| tmp.d[i] = 0; |
| |
| /* |
| * copy mont->N.d[] to improve cache locality |
| */ |
| for (np = am.d + top, i = 0; i < top; i++) |
| np[i] = mont->N.d[i]; |
| |
| bn_scatter5(tmp.d, top, powerbuf, 0); |
| bn_scatter5(am.d, am.top, powerbuf, 1); |
| bn_mul_mont(tmp.d, am.d, am.d, np, n0, top); |
| bn_scatter5(tmp.d, top, powerbuf, 2); |
| |
| # if 0 |
| for (i = 3; i < 32; i++) { |
| /* Calculate a^i = a^(i-1) * a */ |
| bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1); |
| bn_scatter5(tmp.d, top, powerbuf, i); |
| } |
| # else |
| /* same as above, but uses squaring for 1/2 of operations */ |
| for (i = 4; i < 32; i *= 2) { |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_scatter5(tmp.d, top, powerbuf, i); |
| } |
| for (i = 3; i < 8; i += 2) { |
| int j; |
| bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1); |
| bn_scatter5(tmp.d, top, powerbuf, i); |
| for (j = 2 * i; j < 32; j *= 2) { |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_scatter5(tmp.d, top, powerbuf, j); |
| } |
| } |
| for (; i < 16; i += 2) { |
| bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1); |
| bn_scatter5(tmp.d, top, powerbuf, i); |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_scatter5(tmp.d, top, powerbuf, 2 * i); |
| } |
| for (; i < 32; i += 2) { |
| bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1); |
| bn_scatter5(tmp.d, top, powerbuf, i); |
| } |
| # endif |
| /* |
| * The exponent may not have a whole number of fixed-size windows. |
| * To simplify the main loop, the initial window has between 1 and |
| * full-window-size bits such that what remains is always a whole |
| * number of windows |
| */ |
| window0 = (bits - 1) % 5 + 1; |
| wmask = (1 << window0) - 1; |
| bits -= window0; |
| wvalue = bn_get_bits(p, bits) & wmask; |
| bn_gather5(tmp.d, top, powerbuf, wvalue); |
| |
| /* |
| * Scan the exponent one window at a time starting from the most |
| * significant bits. |
| */ |
| if (top & 7) { |
| while (bits > 0) { |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top); |
| bn_mul_mont_gather5(tmp.d, tmp.d, powerbuf, np, n0, top, |
| bn_get_bits5(p->d, bits -= 5)); |
| } |
| } else { |
| while (bits > 0) { |
| bn_power5(tmp.d, tmp.d, powerbuf, np, n0, top, |
| bn_get_bits5(p->d, bits -= 5)); |
| } |
| } |
| |
| ret = bn_from_montgomery(tmp.d, tmp.d, NULL, np, n0, top); |
| tmp.top = top; |
| bn_correct_top(&tmp); |
| if (ret) { |
| if (!BN_copy(rr, &tmp)) |
| ret = 0; |
| goto err; /* non-zero ret means it's not error */ |
| } |
| } else |
| #endif |
| { |
| if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, window)) |
| goto err; |
| if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, window)) |
| goto err; |
| |
| /* |
| * If the window size is greater than 1, then calculate |
| * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1) (even |
| * powers could instead be computed as (a^(i/2))^2 to use the slight |
| * performance advantage of sqr over mul). |
| */ |
| if (window > 1) { |
| if (!bn_mul_mont_fixed_top(&tmp, &am, &am, mont, ctx)) |
| goto err; |
| if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2, |
| window)) |
| goto err; |
| for (i = 3; i < numPowers; i++) { |
| /* Calculate a^i = a^(i-1) * a */ |
| if (!bn_mul_mont_fixed_top(&tmp, &am, &tmp, mont, ctx)) |
| goto err; |
| if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i, |
| window)) |
| goto err; |
| } |
| } |
| |
| /* |
| * The exponent may not have a whole number of fixed-size windows. |
| * To simplify the main loop, the initial window has between 1 and |
| * full-window-size bits such that what remains is always a whole |
| * number of windows |
| */ |
| window0 = (bits - 1) % window + 1; |
| wmask = (1 << window0) - 1; |
| bits -= window0; |
| wvalue = bn_get_bits(p, bits) & wmask; |
| if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp, top, powerbuf, wvalue, |
| window)) |
| goto err; |
| |
| wmask = (1 << window) - 1; |
| /* |
| * Scan the exponent one window at a time starting from the most |
| * significant bits. |
| */ |
| while (bits > 0) { |
| |
| /* Square the result window-size times */ |
| for (i = 0; i < window; i++) |
| if (!bn_mul_mont_fixed_top(&tmp, &tmp, &tmp, mont, ctx)) |
| goto err; |
| |
| /* |
| * Get a window's worth of bits from the exponent |
| * This avoids calling BN_is_bit_set for each bit, which |
| * is not only slower but also makes each bit vulnerable to |
| * EM (and likely other) side-channel attacks like One&Done |
| * (for details see "One&Done: A Single-Decryption EM-Based |
| * Attack on OpenSSL's Constant-Time Blinded RSA" by M. Alam, |
| * H. Khan, M. Dey, N. Sinha, R. Callan, A. Zajic, and |
| * M. Prvulovic, in USENIX Security'18) |
| */ |
| bits -= window; |
| wvalue = bn_get_bits(p, bits) & wmask; |
| /* |
| * Fetch the appropriate pre-computed value from the pre-buf |
| */ |
| if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue, |
| window)) |
| goto err; |
| |
| /* Multiply the result into the intermediate result */ |
| if (!bn_mul_mont_fixed_top(&tmp, &tmp, &am, mont, ctx)) |
| goto err; |
| } |
| } |
| |
| /* |
| * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery |
| * removes padding [if any] and makes return value suitable for public |
| * API consumer. |
| */ |
| #if defined(SPARC_T4_MONT) |
| if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) { |
| am.d[0] = 1; /* borrow am */ |
| for (i = 1; i < top; i++) |
| am.d[i] = 0; |
| if (!BN_mod_mul_montgomery(rr, &tmp, &am, mont, ctx)) |
| goto err; |
| } else |
| #endif |
| if (!BN_from_montgomery(rr, &tmp, mont, ctx)) |
| goto err; |
| ret = 1; |
| err: |
| if (in_mont == NULL) |
| BN_MONT_CTX_free(mont); |
| if (powerbuf != NULL) { |
| OPENSSL_cleanse(powerbuf, powerbufLen); |
| OPENSSL_free(powerbufFree); |
| } |
| BN_CTX_end(ctx); |
| return ret; |
| } |
| |
| int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p, |
| const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont) |
| { |
| BN_MONT_CTX *mont = NULL; |
| int b, bits, ret = 0; |
| int r_is_one; |
| BN_ULONG w, next_w; |
| BIGNUM *r, *t; |
| BIGNUM *swap_tmp; |
| #define BN_MOD_MUL_WORD(r, w, m) \ |
| (BN_mul_word(r, (w)) && \ |
| (/* BN_ucmp(r, (m)) < 0 ? 1 :*/ \ |
| (BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1)))) |
| /* |
| * BN_MOD_MUL_WORD is only used with 'w' large, so the BN_ucmp test is |
| * probably more overhead than always using BN_mod (which uses BN_copy if |
| * a similar test returns true). |
| */ |
| /* |
| * We can use BN_mod and do not need BN_nnmod because our accumulator is |
| * never negative (the result of BN_mod does not depend on the sign of |
| * the modulus). |
| */ |
| #define BN_TO_MONTGOMERY_WORD(r, w, mont) \ |
| (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx)) |
| |
| if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) { |
| /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */ |
| ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); |
| return 0; |
| } |
| |
| bn_check_top(p); |
| bn_check_top(m); |
| |
| if (!BN_is_odd(m)) { |
| ERR_raise(ERR_LIB_BN, BN_R_CALLED_WITH_EVEN_MODULUS); |
| return 0; |
| } |
| if (m->top == 1) |
| a %= m->d[0]; /* make sure that 'a' is reduced */ |
| |
| bits = BN_num_bits(p); |
| if (bits == 0) { |
| /* x**0 mod 1, or x**0 mod -1 is still zero. */ |
| if (BN_abs_is_word(m, 1)) { |
| ret = 1; |
| BN_zero(rr); |
| } else { |
| ret = BN_one(rr); |
| } |
| return ret; |
| } |
| if (a == 0) { |
| BN_zero(rr); |
| ret = 1; |
| return ret; |
| } |
| |
| BN_CTX_start(ctx); |
| r = BN_CTX_get(ctx); |
| t = BN_CTX_get(ctx); |
| if (t == NULL) |
| 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; |
| } |
| |
| r_is_one = 1; /* except for Montgomery factor */ |
| |
| /* bits-1 >= 0 */ |
| |
| /* The result is accumulated in the product r*w. */ |
| w = a; /* bit 'bits-1' of 'p' is always set */ |
| for (b = bits - 2; b >= 0; b--) { |
| /* First, square r*w. */ |
| next_w = w * w; |
| if ((next_w / w) != w) { /* overflow */ |
| if (r_is_one) { |
| if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) |
| goto err; |
| r_is_one = 0; |
| } else { |
| if (!BN_MOD_MUL_WORD(r, w, m)) |
| goto err; |
| } |
| next_w = 1; |
| } |
| w = next_w; |
| if (!r_is_one) { |
| if (!BN_mod_mul_montgomery(r, r, r, mont, ctx)) |
| goto err; |
| } |
| |
| /* Second, multiply r*w by 'a' if exponent bit is set. */ |
| if (BN_is_bit_set(p, b)) { |
| next_w = w * a; |
| if ((next_w / a) != w) { /* overflow */ |
| if (r_is_one) { |
| if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) |
| goto err; |
| r_is_one = 0; |
| } else { |
| if (!BN_MOD_MUL_WORD(r, w, m)) |
| goto err; |
| } |
| next_w = a; |
| } |
| w = next_w; |
| } |
| } |
| |
| /* Finally, set r:=r*w. */ |
| if (w != 1) { |
| if (r_is_one) { |
| if (!BN_TO_MONTGOMERY_WORD(r, w, mont)) |
| goto err; |
| r_is_one = 0; |
| } else { |
| if (!BN_MOD_MUL_WORD(r, w, m)) |
| goto err; |
| } |
| } |
| |
| if (r_is_one) { /* can happen only if a == 1 */ |
| if (!BN_one(rr)) |
| goto err; |
| } else { |
| 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; |
| } |
| |
| /* The old fallback, simple version :-) */ |
| int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, |
| const BIGNUM *m, BN_CTX *ctx) |
| { |
| int i, j, bits, ret = 0, wstart, wend, window, wvalue; |
| int start = 1; |
| BIGNUM *d; |
| /* Table of variables obtained from 'ctx' */ |
| BIGNUM *val[TABLE_SIZE]; |
| |
| if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(a, BN_FLG_CONSTTIME) != 0 |
| || BN_get_flags(m, BN_FLG_CONSTTIME) != 0) { |
| /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */ |
| ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); |
| return 0; |
| } |
| |
| bits = BN_num_bits(p); |
| if (bits == 0) { |
| /* x**0 mod 1, or x**0 mod -1 is still zero. */ |
| if (BN_abs_is_word(m, 1)) { |
| ret = 1; |
| BN_zero(r); |
| } else { |
| ret = BN_one(r); |
| } |
| return ret; |
| } |
| |
| BN_CTX_start(ctx); |
| d = BN_CTX_get(ctx); |
| val[0] = BN_CTX_get(ctx); |
| if (val[0] == NULL) |
| goto err; |
| |
| if (!BN_nnmod(val[0], a, m, ctx)) |
| goto err; /* 1 */ |
| if (BN_is_zero(val[0])) { |
| BN_zero(r); |
| ret = 1; |
| goto err; |
| } |
| |
| window = BN_window_bits_for_exponent_size(bits); |
| if (window > 1) { |
| if (!BN_mod_mul(d, val[0], val[0], m, ctx)) |
| goto err; /* 2 */ |
| j = 1 << (window - 1); |
| for (i = 1; i < j; i++) { |
| if (((val[i] = BN_CTX_get(ctx)) == NULL) || |
| !BN_mod_mul(val[i], val[i - 1], d, m, ctx)) |
| goto err; |
| } |
| } |
| |
| start = 1; /* This is used to avoid multiplication etc |
| * when there is only the value '1' in the |
| * buffer. */ |
| wvalue = 0; /* The 'value' of the window */ |
| wstart = bits - 1; /* The top bit of the window */ |
| wend = 0; /* The bottom bit of the window */ |
| |
| if (!BN_one(r)) |
| goto err; |
| |
| for (;;) { |
| if (BN_is_bit_set(p, wstart) == 0) { |
| if (!start) |
| if (!BN_mod_mul(r, r, r, m, ctx)) |
| goto err; |
| if (wstart == 0) |
| break; |
| wstart--; |
| continue; |
| } |
| /* |
| * We now have wstart on a 'set' bit, we now need to work out how bit |
| * a window to do. To do this we need to scan forward until the last |
| * set bit before the end of the window |
| */ |
| wvalue = 1; |
| wend = 0; |
| for (i = 1; i < window; i++) { |
| if (wstart - i < 0) |
| break; |
| if (BN_is_bit_set(p, wstart - i)) { |
| wvalue <<= (i - wend); |
| wvalue |= 1; |
| wend = i; |
| } |
| } |
| |
| /* wend is the size of the current window */ |
| j = wend + 1; |
| /* add the 'bytes above' */ |
| if (!start) |
| for (i = 0; i < j; i++) { |
| if (!BN_mod_mul(r, r, r, m, ctx)) |
| goto err; |
| } |
| |
| /* wvalue will be an odd number < 2^window */ |
| if (!BN_mod_mul(r, r, val[wvalue >> 1], m, ctx)) |
| goto err; |
| |
| /* move the 'window' down further */ |
| wstart -= wend + 1; |
| wvalue = 0; |
| start = 0; |
| if (wstart < 0) |
| break; |
| } |
| ret = 1; |
| err: |
| BN_CTX_end(ctx); |
| bn_check_top(r); |
| return ret; |
| } |
| |
| /* |
| * This is a variant of modular exponentiation optimization that does |
| * parallel 2-primes exponentiation using 256-bit (AVX512VL) AVX512_IFMA ISA |
| * in 52-bit binary redundant representation. |
| * If such instructions are not available, or input data size is not supported, |
| * it falls back to two BN_mod_exp_mont_consttime() calls. |
| */ |
| int BN_mod_exp_mont_consttime_x2(BIGNUM *rr1, const BIGNUM *a1, const BIGNUM *p1, |
| const BIGNUM *m1, BN_MONT_CTX *in_mont1, |
| BIGNUM *rr2, const BIGNUM *a2, const BIGNUM *p2, |
| const BIGNUM *m2, BN_MONT_CTX *in_mont2, |
| BN_CTX *ctx) |
| { |
| int ret = 0; |
| |
| #ifdef RSAZ_ENABLED |
| BN_MONT_CTX *mont1 = NULL; |
| BN_MONT_CTX *mont2 = NULL; |
| |
| if (ossl_rsaz_avx512ifma_eligible() && |
| (((a1->top == 16) && (p1->top == 16) && (BN_num_bits(m1) == 1024) && |
| (a2->top == 16) && (p2->top == 16) && (BN_num_bits(m2) == 1024)) || |
| ((a1->top == 24) && (p1->top == 24) && (BN_num_bits(m1) == 1536) && |
| (a2->top == 24) && (p2->top == 24) && (BN_num_bits(m2) == 1536)) || |
| ((a1->top == 32) && (p1->top == 32) && (BN_num_bits(m1) == 2048) && |
| (a2->top == 32) && (p2->top == 32) && (BN_num_bits(m2) == 2048)))) { |
| |
| int topn = a1->top; |
| /* Modulus bits of |m1| and |m2| are equal */ |
| int mod_bits = BN_num_bits(m1); |
| |
| if (bn_wexpand(rr1, topn) == NULL) |
| goto err; |
| if (bn_wexpand(rr2, topn) == NULL) |
| goto err; |
| |
| /* Ensure that montgomery contexts are initialized */ |
| if (in_mont1 != NULL) { |
| mont1 = in_mont1; |
| } else { |
| if ((mont1 = BN_MONT_CTX_new()) == NULL) |
| goto err; |
| if (!BN_MONT_CTX_set(mont1, m1, ctx)) |
| goto err; |
| } |
| if (in_mont2 != NULL) { |
| mont2 = in_mont2; |
| } else { |
| if ((mont2 = BN_MONT_CTX_new()) == NULL) |
| goto err; |
| if (!BN_MONT_CTX_set(mont2, m2, ctx)) |
| goto err; |
| } |
| |
| ret = ossl_rsaz_mod_exp_avx512_x2(rr1->d, a1->d, p1->d, m1->d, |
| mont1->RR.d, mont1->n0[0], |
| rr2->d, a2->d, p2->d, m2->d, |
| mont2->RR.d, mont2->n0[0], |
| mod_bits); |
| |
| rr1->top = topn; |
| rr1->neg = 0; |
| bn_correct_top(rr1); |
| bn_check_top(rr1); |
| |
| rr2->top = topn; |
| rr2->neg = 0; |
| bn_correct_top(rr2); |
| bn_check_top(rr2); |
| |
| goto err; |
| } |
| #endif |
| |
| /* rr1 = a1^p1 mod m1 */ |
| ret = BN_mod_exp_mont_consttime(rr1, a1, p1, m1, ctx, in_mont1); |
| /* rr2 = a2^p2 mod m2 */ |
| ret &= BN_mod_exp_mont_consttime(rr2, a2, p2, m2, ctx, in_mont2); |
| |
| #ifdef RSAZ_ENABLED |
| err: |
| if (in_mont2 == NULL) |
| BN_MONT_CTX_free(mont2); |
| if (in_mont1 == NULL) |
| BN_MONT_CTX_free(mont1); |
| #endif |
| |
| return ret; |
| } |
