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Always use |BN_mod_exp_mont|/|BN_mod_exp_mont_consttime| in RSA.

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This removes a hard dependency on |BN_mod_exp|, which will allow the
linker to drop it in programs that don't use other features that
require it.

Also, remove the |mont| member of |bn_blinding_st| in favor of having
callers pass it when necssaary. The |mont| member was a weak reference,
and weak references tend to be error-prone.

Finally, reduce the scope of some parts of the blinding code to
|static|.

Change-Id: I16d8ccc2d6d950c1bb40377988daf1a377a21fe6
Reviewed-on: https://boringssl-review.googlesource.com/7111
Reviewed-by: David Benjamin <davidben@google.com>
This commit is contained in:
Brian Smith
2016-03-08 22:30:19 +00:00
committed by David Benjamin
parent 3ed5977cbb
commit 617804adc5
4 changed files with 30 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crypto/rsa/blinding.c
+16 -33
View File
@@ -125,13 +125,12 @@ struct bn_blinding_st {
BIGNUM *e;
BIGNUM *mod;
int counter;
/* mont is the Montgomery context used for this |BN_BLINDING|. It is not
* owned and must outlive this structure. */
const BN_MONT_CTX *mont;
int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, const BN_MONT_CTX *mont);
};
static BN_BLINDING *bn_blinding_create_param(BN_BLINDING *b, const BIGNUM *e,
BIGNUM *m, BN_CTX *ctx,
const BN_MONT_CTX *mont_ctx);
BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod) {
BN_BLINDING *ret = NULL;
@@ -159,9 +158,7 @@ BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod) {
if (ret->mod == NULL) {
goto err;
}
if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0) {
BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
}
BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
/* Set the counter to the special value -1
* to indicate that this is never-used fresh blinding
@@ -186,7 +183,8 @@ void BN_BLINDING_free(BN_BLINDING *r) {
OPENSSL_free(r);
}
int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx) {
static int bn_blinding_update(BN_BLINDING *b, BN_CTX *ctx,
const BN_MONT_CTX *mont_ctx) {
int ret = 0;
if (b->A == NULL || b->Ai == NULL) {
@@ -200,7 +198,7 @@ int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx) {
if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL) {
/* re-create blinding parameters */
if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL)) {
if (!bn_blinding_create_param(b, NULL, NULL, ctx, mont_ctx)) {
goto err;
}
} else {
@@ -221,7 +219,8 @@ err:
return ret;
}
int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx) {
int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx,
const BN_MONT_CTX *mont_ctx) {
int ret = 1;
if (b->A == NULL || b->Ai == NULL) {
@@ -232,7 +231,7 @@ int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx) {
if (b->counter == -1) {
/* Fresh blinding, doesn't need updating. */
b->counter = 0;
} else if (!BN_BLINDING_update(b, ctx)) {
} else if (!bn_blinding_update(b, ctx, mont_ctx)) {
return 0;
}
@@ -251,11 +250,9 @@ int BN_BLINDING_invert(BIGNUM *n, const BN_BLINDING *b, BN_CTX *ctx) {
return BN_mod_mul(n, n, b->Ai, b->mod, ctx);
}
BN_BLINDING *BN_BLINDING_create_param(
static BN_BLINDING *bn_blinding_create_param(
BN_BLINDING *b, const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, const BN_MONT_CTX *mont),
const BN_MONT_CTX *mont) {
const BN_MONT_CTX *mont_ctx) {
int retry_counter = 32;
BN_BLINDING *ret = NULL;
@@ -284,13 +281,6 @@ BN_BLINDING *BN_BLINDING_create_param(
goto err;
}
if (bn_mod_exp != NULL) {
ret->bn_mod_exp = bn_mod_exp;
}
if (mont != NULL) {
ret->mont = mont;
}
do {
if (!BN_rand_range(ret->A, ret->mod)) {
goto err;
@@ -313,14 +303,8 @@ BN_BLINDING *BN_BLINDING_create_param(
}
} while (1);
if (ret->bn_mod_exp != NULL && ret->mont != NULL) {
if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->mont)) {
goto err;
}
} else {
if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx)) {
goto err;
}
if (!BN_mod_exp_mont(ret->A, ret->A, ret->e, ret->mod, ctx, mont_ctx)) {
goto err;
}
return ret;
@@ -403,8 +387,7 @@ BN_BLINDING *rsa_setup_blinding(RSA *rsa, BN_CTX *in_ctx) {
}
}
ret = BN_BLINDING_create_param(NULL, e, n, ctx, rsa->meth->bn_mod_exp,
mont_ctx);
ret = bn_blinding_create_param(NULL, e, n, ctx, mont_ctx);
if (ret == NULL) {
OPENSSL_PUT_ERROR(RSA, ERR_R_BN_LIB);
goto err;
crypto/rsa/internal.h
+2 -7
View File
@@ -92,14 +92,9 @@ int rsa_default_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb);
BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod);
void BN_BLINDING_free(BN_BLINDING *b);
int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx);
int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx);
int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx,
const BN_MONT_CTX *mont_ctx);
int BN_BLINDING_invert(BIGNUM *n, const BN_BLINDING *b, BN_CTX *ctx);
BN_BLINDING *BN_BLINDING_create_param(
BN_BLINDING *b, const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, const BN_MONT_CTX *mont),
const BN_MONT_CTX *mont);
BN_BLINDING *rsa_setup_blinding(RSA *rsa, BN_CTX *in_ctx);
crypto/rsa/rsa_impl.c
+10 -10
View File
@@ -177,7 +177,7 @@ int rsa_default_encrypt(RSA *rsa, size_t *out_len, uint8_t *out, size_t max_out,
}
}
if (!rsa->meth->bn_mod_exp(result, f, rsa->e, rsa->n, ctx, rsa->mont_n)) {
if (!BN_mod_exp_mont(result, f, rsa->e, rsa->n, ctx, rsa->mont_n)) {
goto err;
}
@@ -488,7 +488,7 @@ int rsa_default_verify_raw(RSA *rsa, size_t *out_len, uint8_t *out,
}
}
if (!rsa->meth->bn_mod_exp(result, f, rsa->e, rsa->n, ctx, rsa->mont_n)) {
if (!BN_mod_exp_mont(result, f, rsa->e, rsa->n, ctx, rsa->mont_n)) {
goto err;
}
@@ -565,7 +565,7 @@ int rsa_default_private_transform(RSA *rsa, uint8_t *out, const uint8_t *in,
OPENSSL_PUT_ERROR(RSA, ERR_R_INTERNAL_ERROR);
goto err;
}
if (!BN_BLINDING_convert(f, blinding, ctx)) {
if (!BN_BLINDING_convert(f, blinding, ctx, rsa->mont_n)) {
goto err;
}
}
@@ -591,7 +591,7 @@ int rsa_default_private_transform(RSA *rsa, uint8_t *out, const uint8_t *in,
}
}
if (!rsa->meth->bn_mod_exp(result, f, d, rsa->n, ctx, rsa->mont_n)) {
if (!BN_mod_exp_mont_consttime(result, f, d, rsa->n, ctx, rsa->mont_n)) {
goto err;
}
}
@@ -677,7 +677,7 @@ static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) {
/* compute r1^dmq1 mod q */
dmq1 = &local_dmq1;
BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
if (!rsa->meth->bn_mod_exp(m1, r1, dmq1, rsa->q, ctx, rsa->mont_q)) {
if (!BN_mod_exp_mont_consttime(m1, r1, dmq1, rsa->q, ctx, rsa->mont_q)) {
goto err;
}
@@ -691,7 +691,7 @@ static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) {
/* compute r1^dmp1 mod p */
dmp1 = &local_dmp1;
BN_with_flags(dmp1, rsa->dmp1, BN_FLG_CONSTTIME);
if (!rsa->meth->bn_mod_exp(r0, r1, dmp1, rsa->p, ctx, rsa->mont_p)) {
if (!BN_mod_exp_mont_consttime(r0, r1, dmp1, rsa->p, ctx, rsa->mont_p)) {
goto err;
}
@@ -756,7 +756,7 @@ static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) {
goto err;
}
if (!rsa->meth->bn_mod_exp(m1, r1, exp, prime, ctx, ap->mont)) {
if (!BN_mod_exp_mont_consttime(m1, r1, exp, prime, ctx, ap->mont)) {
goto err;
}
@@ -773,7 +773,7 @@ static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) {
}
if (rsa->e && rsa->n) {
if (!rsa->meth->bn_mod_exp(vrfy, r0, rsa->e, rsa->n, ctx, rsa->mont_n)) {
if (!BN_mod_exp_mont(vrfy, r0, rsa->e, rsa->n, ctx, rsa->mont_n)) {
goto err;
}
/* If 'I' was greater than (or equal to) rsa->n, the operation
@@ -801,7 +801,7 @@ static int mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx) {
d = &local_d;
BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
if (!rsa->meth->bn_mod_exp(r0, I, d, rsa->n, ctx, rsa->mont_n)) {
if (!BN_mod_exp_mont_consttime(r0, I, d, rsa->n, ctx, rsa->mont_n)) {
goto err;
}
}
@@ -1133,7 +1133,7 @@ const RSA_METHOD RSA_default_method = {
NULL /* private_transform (defaults to rsa_default_private_transform) */,
mod_exp,
BN_mod_exp_mont /* bn_mod_exp */,
NULL /* bn_mod_exp */,
RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE,
include/openssl/rsa.h
+2
View File
@@ -525,6 +525,8 @@ struct rsa_meth_st {
int (*mod_exp)(BIGNUM *r0, const BIGNUM *I, RSA *rsa,
BN_CTX *ctx); /* Can be null */
/* bn_mod_exp is deprecated and ignored. Set it to NULL. */
int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx,
const BN_MONT_CTX *mont);