diff options
Diffstat (limited to 'deps/openssl/openssl/crypto/dsa/dsa_ossl.c')
| -rw-r--r-- | deps/openssl/openssl/crypto/dsa/dsa_ossl.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/deps/openssl/openssl/crypto/dsa/dsa_ossl.c b/deps/openssl/openssl/crypto/dsa/dsa_ossl.c index 3b657d5d3d..be58625db3 100644 --- a/deps/openssl/openssl/crypto/dsa/dsa_ossl.c +++ b/deps/openssl/openssl/crypto/dsa/dsa_ossl.c @@ -11,6 +11,7 @@ #include <stdio.h> #include "internal/cryptlib.h" +#include "internal/bn_int.h" #include <openssl/bn.h> #include <openssl/sha.h> #include "dsa_locl.h" @@ -182,9 +183,9 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, { BN_CTX *ctx = NULL; BIGNUM *k, *kinv = NULL, *r = *rp; - BIGNUM *l, *m; + BIGNUM *l; int ret = 0; - int q_bits; + int q_bits, q_words; if (!dsa->p || !dsa->q || !dsa->g) { DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS); @@ -193,8 +194,7 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, k = BN_new(); l = BN_new(); - m = BN_new(); - if (k == NULL || l == NULL || m == NULL) + if (k == NULL || l == NULL) goto err; if (ctx_in == NULL) { @@ -205,9 +205,9 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, /* Preallocate space */ q_bits = BN_num_bits(dsa->q); - if (!BN_set_bit(k, q_bits) - || !BN_set_bit(l, q_bits) - || !BN_set_bit(m, q_bits)) + q_words = bn_get_top(dsa->q); + if (!bn_wexpand(k, q_words + 2) + || !bn_wexpand(l, q_words + 2)) goto err; /* Get random k */ @@ -242,14 +242,17 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, * small timing information leakage. We then choose the sum that is * one bit longer than the modulus. * - * TODO: revisit the BN_copy aiming for a memory access agnostic - * conditional copy. + * There are some concerns about the efficacy of doing this. More + * specificly refer to the discussion starting with: + * https://github.com/openssl/openssl/pull/7486#discussion_r228323705 + * The fix is to rework BN so these gymnastics aren't required. */ if (!BN_add(l, k, dsa->q) - || !BN_add(m, l, dsa->q) - || !BN_copy(k, BN_num_bits(l) > q_bits ? l : m)) + || !BN_add(k, l, dsa->q)) goto err; + BN_consttime_swap(BN_is_bit_set(l, q_bits), k, l, q_words + 2); + if ((dsa)->meth->bn_mod_exp != NULL) { if (!dsa->meth->bn_mod_exp(dsa, r, dsa->g, k, dsa->p, ctx, dsa->method_mont_p)) @@ -262,7 +265,7 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, if (!BN_mod(r, r, dsa->q, ctx)) goto err; - /* Compute part of 's = inv(k) (m + xr) mod q' */ + /* Compute part of 's = inv(k) (m + xr) mod q' */ if ((kinv = dsa_mod_inverse_fermat(k, dsa->q, ctx)) == NULL) goto err; @@ -277,7 +280,6 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BN_CTX_free(ctx); BN_clear_free(k); BN_clear_free(l); - BN_clear_free(m); return ret; } |