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add wc_DhCheckPubKey_ex() with checks against large prime q

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This commit is contained in:
Chris Conlon
2018-02-21 11:50:56 -07:00
parent 41ae47fa3c
commit de4893486e
2 changed files with 78 additions and 36 deletions
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112
wolfcrypt/src/dh.c
View File

@@ -728,6 +728,81 @@ static int wc_DhGenerateKeyPair_Async(DhKey* key, WC_RNG* rng,
#endif /* WOLFSSL_ASYNC_CRYPT && WC_ASYNC_ENABLE_DH */ #endif /* WOLFSSL_ASYNC_CRYPT && WC_ASYNC_ENABLE_DH */
/* Check DH Public Key for invalid numbers, optionally allowing
* the public key to be checked against the large prime (q).
*
* key DH key group parameters.
* pub Public Key.
* pubSz Public Key size.
* prime Large prime (q), optionally NULL to skip check
* primeSz Size of large prime
*
* returns 0 on success or error code
*/
int wc_DhCheckPubKey_ex(DhKey* key, const byte* pub, word32 pubSz,
const byte* prime, word32 primeSz)
{
int ret = 0;
mp_int y;
mp_int p;
mp_int q;
if (key == NULL || pub == NULL) {
return BAD_FUNC_ARG;
}
if (mp_init_multi(&y, &p, &q, NULL, NULL, NULL) != MP_OKAY) {
return MP_INIT_E;
}
if (mp_read_unsigned_bin(&y, pub, pubSz) != MP_OKAY) {
ret = MP_READ_E;
}
if (ret == 0 && prime != NULL) {
if (mp_read_unsigned_bin(&q, prime, primeSz) != MP_OKAY)
ret = MP_READ_E;
}
/* pub (y) should not be 0 or 1 */
if (ret == 0 && mp_cmp_d(&y, 2) == MP_LT) {
ret = MP_CMP_E;
}
/* pub (y) shouldn't be greater than or equal to p - 1 */
if (ret == 0 && mp_copy(&key->p, &p) != MP_OKAY) {
ret = MP_INIT_E;
}
if (ret == 0 && mp_sub_d(&p, 2, &p) != MP_OKAY) {
ret = MP_SUB_E;
}
if (ret == 0 && mp_cmp(&y, &p) == MP_GT) {
ret = MP_CMP_E;
}
if (ret == 0 && prime != NULL) {
/* restore key->p into p */
if (mp_copy(&key->p, &p) != MP_OKAY)
ret = MP_INIT_E;
/* calculate (y^q) mod(p), store back into y */
if (ret == 0 && mp_exptmod(&y, &q, &p, &y) != MP_OKAY)
ret = MP_EXPTMOD_E;
/* verify above == 1 */
if (ret == 0 && mp_cmp_d(&y, 1) != MP_EQ)
ret = MP_CMP_E;
}
mp_clear(&y);
mp_clear(&p);
mp_clear(&q);
return ret;
}
/* Check DH Public Key for invalid numbers /* Check DH Public Key for invalid numbers
* *
* key DH key group parameters. * key DH key group parameters.
@@ -738,42 +813,7 @@ static int wc_DhGenerateKeyPair_Async(DhKey* key, WC_RNG* rng,
*/ */
int wc_DhCheckPubKey(DhKey* key, const byte* pub, word32 pubSz) int wc_DhCheckPubKey(DhKey* key, const byte* pub, word32 pubSz)
{ {
int ret = 0; return wc_DhCheckPubKey_ex(key, pub, pubSz, NULL, 0);
mp_int x;
mp_int y;
if (key == NULL || pub == NULL) {
return BAD_FUNC_ARG;
}
if (mp_init_multi(&x, &y, NULL, NULL, NULL, NULL) != MP_OKAY) {
return MP_INIT_E;
}
if (mp_read_unsigned_bin(&x, pub, pubSz) != MP_OKAY) {
ret = MP_READ_E;
}
/* pub should not be 0 or 1 */
if (ret == 0 && mp_cmp_d(&x, 2) == MP_LT) {
ret = MP_CMP_E;
}
/* pub shouldn't be greater than or equal to p - 1 */
if (ret == 0 && mp_copy(&key->p, &y) != MP_OKAY) {
ret = MP_INIT_E;
}
if (ret == 0 && mp_sub_d(&y, 2, &y) != MP_OKAY) {
ret = MP_SUB_E;
}
if (ret == 0 && mp_cmp(&x, &y) == MP_GT) {
ret = MP_CMP_E;
}
mp_clear(&y);
mp_clear(&x);
return ret;
} }

2
wolfssl/wolfcrypt/dh.h
View File

@@ -87,6 +87,8 @@ WOLFSSL_API int wc_DhSetKey(DhKey* key, const byte* p, word32 pSz, const byte* g
WOLFSSL_API int wc_DhParamsLoad(const byte* input, word32 inSz, byte* p, WOLFSSL_API int wc_DhParamsLoad(const byte* input, word32 inSz, byte* p,
word32* pInOutSz, byte* g, word32* gInOutSz); word32* pInOutSz, byte* g, word32* gInOutSz);
WOLFSSL_API int wc_DhCheckPubKey(DhKey* key, const byte* pub, word32 pubSz); WOLFSSL_API int wc_DhCheckPubKey(DhKey* key, const byte* pub, word32 pubSz);
WOLFSSL_API int wc_DhCheckPubKey_ex(DhKey* key, const byte* pub, word32 pubSz,
const byte* prime, word32 primeSz);
#ifdef __cplusplus #ifdef __cplusplus
} /* extern "C" */ } /* extern "C" */