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deps: float 0c27d793 from openssl (ECDSA blinding) #21345

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deps: float 0c27d793 from openssl (ECDSA blinding) #21345

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70 changes: 63 additions & 7 deletions deps/openssl/openssl/crypto/ec/ecdsa_ossl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -210,7 +210,8 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
EC_KEY *eckey)
{
int ok = 0, i;
BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL;
BIGNUM *kinv = NULL, *s, *m = NULL, *tmp = NULL, *blind = NULL;
BIGNUM *blindm = NULL;
const BIGNUM *order, *ckinv;
BN_CTX *ctx = NULL;
const EC_GROUP *group;
Expand Down Expand Up @@ -243,8 +244,18 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
}
s = ret->s;

if ((ctx = BN_CTX_new()) == NULL ||
(tmp = BN_new()) == NULL || (m = BN_new()) == NULL) {
ctx = BN_CTX_secure_new();
if (ctx == NULL) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
goto err;
}

BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
m = BN_CTX_get(ctx);
blind = BN_CTX_get(ctx);
blindm = BN_CTX_get(ctx);
if (blindm == NULL) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_MALLOC_FAILURE);
goto err;
}
Expand Down Expand Up @@ -284,18 +295,64 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
}
}

if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx)) {
/*
* The normal signature calculation is:
*
* s := k^-1 * (m + r * priv_key) mod order
*
* We will blind this to protect against side channel attacks
*
* s := k^-1 * blind^-1 * (blind * m + blind * r * priv_key) mod order
*/

/* Generate a blinding value */
do {
if (!BN_rand(blind, BN_num_bits(order) - 1, BN_RAND_TOP_ANY,
BN_RAND_BOTTOM_ANY))
goto err;
} while (BN_is_zero(blind));
BN_set_flags(blind, BN_FLG_CONSTTIME);
BN_set_flags(blindm, BN_FLG_CONSTTIME);
BN_set_flags(tmp, BN_FLG_CONSTTIME);

/* tmp := blind * priv_key * r mod order */
if (!BN_mod_mul(tmp, blind, priv_key, order, ctx)) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}
if (!BN_mod_add_quick(s, tmp, m, order)) {
if (!BN_mod_mul(tmp, tmp, ret->r, order, ctx)) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}

/* blindm := blind * m mod order */
if (!BN_mod_mul(blindm, blind, m, order, ctx)) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}

/* s : = (blind * priv_key * r) + (blind * m) mod order */
if (!BN_mod_add_quick(s, tmp, blindm, order)) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}

/* s:= s * blind^-1 mod order */
if (BN_mod_inverse(blind, blind, order, ctx) == NULL) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}
if (!BN_mod_mul(s, s, blind, order, ctx)) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}

/* s := s * k^-1 mod order */
if (!BN_mod_mul(s, s, ckinv, order, ctx)) {
ECerr(EC_F_OSSL_ECDSA_SIGN_SIG, ERR_R_BN_LIB);
goto err;
}

if (BN_is_zero(s)) {
/*
* if kinv and r have been supplied by the caller don't to
Expand All @@ -317,9 +374,8 @@ ECDSA_SIG *ossl_ecdsa_sign_sig(const unsigned char *dgst, int dgst_len,
ECDSA_SIG_free(ret);
ret = NULL;
}
BN_CTX_end(ctx);
BN_CTX_free(ctx);
BN_clear_free(m);
BN_clear_free(tmp);
BN_clear_free(kinv);
return ret;
}
Expand Down