/*
- * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2019 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
int i, bits, ret = 0;
BIGNUM *v, *rr;
- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0) {
+ 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() */
BNerr(BN_F_BN_EXP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
return 0;
}
BN_CTX_start(ctx);
- if ((r == a) || (r == p))
- rr = BN_CTX_get(ctx);
- else
- rr = r;
+ rr = ((r == a) || (r == p)) ? BN_CTX_get(ctx) : r;
v = BN_CTX_get(ctx);
if (rr == NULL || v == NULL)
goto err;
err:
BN_CTX_end(ctx);
bn_check_top(r);
- return (ret);
+ return ret;
}
int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
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(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
bn_check_top(r);
- return (ret);
+ return ret;
}
int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
BIGNUM *val[TABLE_SIZE];
BN_RECP_CTX recp;
- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0) {
+ 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() */
BNerr(BN_F_BN_MOD_EXP_RECP, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
return 0;
bits = BN_num_bits(p);
if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ /* 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 {
BN_CTX_start(ctx);
aa = BN_CTX_get(ctx);
val[0] = BN_CTX_get(ctx);
- if (!aa || !val[0])
+ if (val[0] == NULL)
goto err;
BN_RECP_CTX_init(&recp);
BN_CTX_end(ctx);
BN_RECP_CTX_free(&recp);
bn_check_top(r);
- return (ret);
+ return ret;
}
int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
BIGNUM *val[TABLE_SIZE];
BN_MONT_CTX *mont = NULL;
- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0) {
+ 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);
}
if (!BN_is_odd(m)) {
BNerr(BN_F_BN_MOD_EXP_MONT, BN_R_CALLED_WITH_EVEN_MODULUS);
- return (0);
+ return 0;
}
bits = BN_num_bits(p);
if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ /* 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 {
d = BN_CTX_get(ctx);
r = BN_CTX_get(ctx);
val[0] = BN_CTX_get(ctx);
- if (!d || !r || !val[0])
+ if (val[0] == NULL)
goto err;
/*
aa = val[0];
} else
aa = a;
- if (BN_is_zero(aa)) {
- BN_zero(rr);
- ret = 1;
- goto err;
- }
- if (!BN_to_montgomery(val[0], aa, mont, ctx))
+ 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_mod_mul_montgomery(d, val[0], val[0], mont, ctx))
+ 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_mod_mul_montgomery(val[i], val[i - 1], d, mont, ctx))
+ !bn_mul_mont_fixed_top(val[i], val[i - 1], d, mont, ctx))
goto err;
}
}
for (i = 1; i < j; i++)
r->d[i] = (~m->d[i]) & BN_MASK2;
r->top = j;
- /*
- * Upper words will be zero if the corresponding words of 'm' were
- * 0xfff[...], so decrement r->top accordingly.
- */
- bn_correct_top(r);
+ r->flags |= BN_FLG_FIXED_TOP;
} else
#endif
- if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))
+ 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_mod_mul_montgomery(r, r, r, mont, ctx))
+ if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx))
goto err;
}
if (wstart == 0)
/* add the 'bytes above' */
if (!start)
for (i = 0; i < j; i++) {
- if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
+ if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx))
goto err;
}
/* wvalue will be an odd number < 2^window */
- if (!BN_mod_mul_montgomery(r, r, val[wvalue >> 1], mont, ctx))
+ if (!bn_mul_mont_fixed_top(r, r, val[wvalue >> 1], mont, ctx))
goto err;
/* move the 'window' down further */
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 */
BN_MONT_CTX_free(mont);
BN_CTX_end(ctx);
bn_check_top(rr);
- return (ret);
+ return ret;
}
-#if defined(SPARC_T4_MONT)
static BN_ULONG bn_get_bits(const BIGNUM *a, int bitpos)
{
BN_ULONG ret = 0;
return ret & BN_MASK2;
}
-#endif
/*
* BN_mod_exp_mont_consttime() stores the precomputed powers in a specific
}
b->top = top;
- bn_correct_top(b);
+ b->flags |= BN_FLG_FIXED_TOP;
return 1;
}
const BIGNUM *m, BN_CTX *ctx,
BN_MONT_CTX *in_mont)
{
- int i, bits, ret = 0, window, wvalue;
+ int i, bits, ret = 0, window, wvalue, wmask, window0;
int top;
BN_MONT_CTX *mont = NULL;
if (!BN_is_odd(m)) {
BNerr(BN_F_BN_MOD_EXP_MONT_CONSTTIME, BN_R_CALLED_WITH_EVEN_MODULUS);
- return (0);
+ return 0;
}
top = m->top;
- bits = BN_num_bits(p);
+ /*
+ * 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 is still zero. */
- if (BN_is_one(m)) {
+ /* 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 {
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
tmp.top = top;
} else
#endif
- if (!BN_to_montgomery(&tmp, BN_value_one(), mont, ctx))
+ if (!bn_to_mont_fixed_top(&tmp, BN_value_one(), mont, ctx))
goto err;
/* prepare a^1 in Montgomery domain */
- if (a->neg || BN_ucmp(a, m) >= 0) {
- if (!BN_mod(&am, a, m, ctx))
- goto err;
- if (!BN_to_montgomery(&am, &am, mont, ctx))
- goto err;
- } else if (!BN_to_montgomery(&am, a, mont, ctx))
+ if (!bn_to_mont_fixed_top(&am, a, mont, ctx))
goto err;
#if defined(SPARC_T4_MONT)
top /= 2;
bn_flip_t4(np, mont->N.d, top);
- bits--;
- for (wvalue = 0, i = bits % 5; i >= 0; i--, bits--)
- wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ /*
+ * 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) {
+ while (bits > 0) {
if (bits < stride)
- stride = bits + 1;
+ stride = bits;
bits -= stride;
- wvalue = bn_get_bits(p, bits + 1);
+ wvalue = bn_get_bits(p, bits);
if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride))
continue;
bn_scatter5(tmp.d, top, powerbuf, i);
}
# endif
- bits--;
- for (wvalue = 0, i = bits % 5; i >= 0; i--, bits--)
- wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ /*
+ * 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) {
- for (wvalue = 0, i = 0; i < 5; i++, bits--)
- wvalue = (wvalue << 1) + BN_is_bit_set(p, 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,
- wvalue);
+ bn_get_bits5(p->d, bits -= 5));
+ }
} else {
- while (bits >= 0) {
- wvalue = bn_get_bits5(p->d, bits - 4);
- bits -= 5;
- bn_power5(tmp.d, tmp.d, powerbuf, np, n0, top, wvalue);
+ while (bits > 0) {
+ bn_power5(tmp.d, tmp.d, powerbuf, np, n0, top,
+ bn_get_bits5(p->d, bits -= 5));
}
}
* performance advantage of sqr over mul).
*/
if (window > 1) {
- if (!BN_mod_mul_montgomery(&tmp, &am, &am, mont, ctx))
+ 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_mod_mul_montgomery(&tmp, &am, &tmp, mont, ctx))
+ 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))
}
}
- bits--;
- for (wvalue = 0, i = bits % window; i >= 0; i--, bits--)
- wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ /*
+ * 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) {
- wvalue = 0; /* The 'value' of the window */
+ while (bits > 0) {
- /* Scan the window, squaring the result as we go */
- for (i = 0; i < window; i++, bits--) {
- if (!BN_mod_mul_montgomery(&tmp, &tmp, &tmp, mont, ctx))
+ /* 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;
- wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
- }
+ /*
+ * 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
*/
goto err;
/* Multiply the result into the intermediate result */
- if (!BN_mod_mul_montgomery(&tmp, &tmp, &am, mont, ctx))
+ if (!bn_mul_mont_fixed_top(&tmp, &tmp, &am, mont, ctx))
goto err;
}
}
- /* Convert the final result from montgomery to standard format */
+ /*
+ * 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 */
OPENSSL_free(powerbufFree);
}
BN_CTX_end(ctx);
- return (ret);
+ return ret;
}
int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONG a, const BIGNUM *p,
int b, bits, ret = 0;
int r_is_one;
BN_ULONG w, next_w;
- BIGNUM *d, *r, *t;
+ BIGNUM *r, *t;
BIGNUM *swap_tmp;
#define BN_MOD_MUL_WORD(r, w, m) \
(BN_mul_word(r, (w)) && \
#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) {
+ 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() */
BNerr(BN_F_BN_MOD_EXP_MONT_WORD, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
return 0;
if (!BN_is_odd(m)) {
BNerr(BN_F_BN_MOD_EXP_MONT_WORD, BN_R_CALLED_WITH_EVEN_MODULUS);
- return (0);
+ 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 is still zero. */
- if (BN_is_one(m)) {
+ /* 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 {
}
BN_CTX_start(ctx);
- d = BN_CTX_get(ctx);
r = BN_CTX_get(ctx);
t = BN_CTX_get(ctx);
- if (d == NULL || r == NULL || t == NULL)
+ if (t == NULL)
goto err;
if (in_mont != NULL)
BN_MONT_CTX_free(mont);
BN_CTX_end(ctx);
bn_check_top(rr);
- return (ret);
+ return ret;
}
/* The old fallback, simple version :-) */
/* Table of variables obtained from 'ctx' */
BIGNUM *val[TABLE_SIZE];
- if (BN_get_flags(p, BN_FLG_CONSTTIME) != 0) {
+ 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() */
BNerr(BN_F_BN_MOD_EXP_SIMPLE, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
return 0;
}
bits = BN_num_bits(p);
- if (bits == 0) {
- /* x**0 mod 1 is still zero. */
- if (BN_is_one(m)) {
+ 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 {
BN_CTX_start(ctx);
d = BN_CTX_get(ctx);
val[0] = BN_CTX_get(ctx);
- if (!d || !val[0])
+ if (val[0] == NULL)
goto err;
if (!BN_nnmod(val[0], a, m, ctx))
err:
BN_CTX_end(ctx);
bn_check_top(r);
- return (ret);
+ return ret;
}
projects / openssl.git / blobdiff