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Remove signature verification from mbedtls_rsa_rsassa_pkcs1_v15_sign

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This is no longer necessary as we're now always verifying the result of rsa_private.
This commit is contained in:
Hanno Becker 2017-11-06 15:09:33 +00:00
parent de0b70c366
commit 21f83753f5
1 changed files with 1 additions and 41 deletions
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42
library/rsa.c
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@ -1207,11 +1207,6 @@ int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
size_t nb_pad, olen, oid_size = 0;
unsigned char *p = sig;
const char *oid = NULL;
unsigned char *sig_try = NULL, *verif = NULL;
size_t i;
unsigned char diff;
volatile unsigned char diff_no_optimize;
int ret;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
@ -1277,42 +1272,7 @@ int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
if( mode == MBEDTLS_RSA_PUBLIC )
return( mbedtls_rsa_public( ctx, sig, sig ) );
/*
* In order to prevent Lenstra's attack, make the signature in a
* temporary buffer and check it before returning it.
*/
sig_try = mbedtls_calloc( 1, ctx->len );
if( sig_try == NULL )
return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
verif = mbedtls_calloc( 1, ctx->len );
if( verif == NULL )
{
mbedtls_free( sig_try );
return( MBEDTLS_ERR_MPI_ALLOC_FAILED );
}
MBEDTLS_MPI_CHK( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig_try ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_public( ctx, sig_try, verif ) );
/* Compare in constant time just in case */
for( diff = 0, i = 0; i < ctx->len; i++ )
diff |= verif[i] ^ sig[i];
diff_no_optimize = diff;
if( diff_no_optimize != 0 )
{
ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
goto cleanup;
}
memcpy( sig, sig_try, ctx->len );
cleanup:
mbedtls_free( sig_try );
mbedtls_free( verif );
return( ret );
return( mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) );
}
#endif /* MBEDTLS_PKCS1_V15 */