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/*
* The RSA public-key cryptosystem
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
/*
* The following sources were referenced in the design of this implementation
* of the RSA algorithm:
*
* [1] A method for obtaining digital signatures and public-key cryptosystems
* R Rivest, A Shamir, and L Adleman
* http://people.csail.mit.edu/rivest/pubs.html#RSA78
*
* [2] Handbook of Applied Cryptography - 1997, Chapter 8
* Menezes, van Oorschot and Vanstone
*
* [3] Malware Guard Extension: Using SGX to Conceal Cache Attacks
* Michael Schwarz, Samuel Weiser, Daniel Gruss, Clémentine Maurice and
* Stefan Mangard
* https://arxiv.org/abs/1702.08719v2
*
*/
#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_RSA_C)
#include "mbedtls/rsa.h"
#include "mbedtls/rsa_internal.h"
#include "mbedtls/oid.h"
#include <string.h>
#if defined(MBEDTLS_PKCS1_V21)
#include "mbedtls/md.h"
#endif
#if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__)
#include <stdlib.h>
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdio.h>
#define mbedtls_printf printf
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#if !defined(MBEDTLS_RSA_ALT)
/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n ) {
volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
}
#if defined(MBEDTLS_PKCS1_V15)
/* constant-time buffer comparison */
static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n )
{
size_t i;
const unsigned char *A = (const unsigned char *) a;
const unsigned char *B = (const unsigned char *) b;
unsigned char diff = 0;
for( i = 0; i < n; i++ )
diff |= A[i] ^ B[i];
return( diff );
}
#endif /* MBEDTLS_PKCS1_V15 */
int mbedtls_rsa_import( mbedtls_rsa_context *ctx,
const mbedtls_mpi *N,
const mbedtls_mpi *P, const mbedtls_mpi *Q,
const mbedtls_mpi *D, const mbedtls_mpi *E )
{
int ret;
if( ( N != NULL && ( ret = mbedtls_mpi_copy( &ctx->N, N ) ) != 0 ) ||
( P != NULL && ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ) ||
( Q != NULL && ( ret = mbedtls_mpi_copy( &ctx->Q, Q ) ) != 0 ) ||
( D != NULL && ( ret = mbedtls_mpi_copy( &ctx->D, D ) ) != 0 ) ||
( E != NULL && ( ret = mbedtls_mpi_copy( &ctx->E, E ) ) != 0 ) )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
if( N != NULL )
ctx->len = mbedtls_mpi_size( &ctx->N );
return( 0 );
}
int mbedtls_rsa_import_raw( mbedtls_rsa_context *ctx,
unsigned char const *N, size_t N_len,
unsigned char const *P, size_t P_len,
unsigned char const *Q, size_t Q_len,
unsigned char const *D, size_t D_len,
unsigned char const *E, size_t E_len )
{
int ret = 0;
if( N != NULL )
{
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->N, N, N_len ) );
ctx->len = mbedtls_mpi_size( &ctx->N );
}
if( P != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->P, P, P_len ) );
if( Q != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->Q, Q, Q_len ) );
if( D != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->D, D, D_len ) );
if( E != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &ctx->E, E, E_len ) );
cleanup:
if( ret != 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
return( 0 );
}
/*
* Checks whether the context fields are set in such a way
* that the RSA primitives will be able to execute without error.
* It does *not* make guarantees for consistency of the parameters.
*/
static int rsa_check_context( mbedtls_rsa_context const *ctx, int is_priv,
int blinding_needed )
{
#if !defined(MBEDTLS_RSA_NO_CRT)
/* blinding_needed is only used for NO_CRT to decide whether
* P,Q need to be present or not. */
((void) blinding_needed);
#endif
if( ctx->len != mbedtls_mpi_size( &ctx->N ) ||
ctx->len > MBEDTLS_MPI_MAX_SIZE )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
/*
* 1. Modular exponentiation needs positive, odd moduli.
*/
/* Modular exponentiation wrt. N is always used for
* RSA public key operations. */
if( mbedtls_mpi_cmp_int( &ctx->N, 0 ) <= 0 ||
mbedtls_mpi_get_bit( &ctx->N, 0 ) == 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#if !defined(MBEDTLS_RSA_NO_CRT)
/* Modular exponentiation for P and Q is only
* used for private key operations and if CRT
* is used. */
if( is_priv &&
( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 ||
mbedtls_mpi_get_bit( &ctx->P, 0 ) == 0 ||
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 ||
mbedtls_mpi_get_bit( &ctx->Q, 0 ) == 0 ) )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#endif /* !MBEDTLS_RSA_NO_CRT */
/*
* 2. Exponents must be positive
*/
/* Always need E for public key operations */
if( mbedtls_mpi_cmp_int( &ctx->E, 0 ) <= 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
#if defined(MBEDTLS_RSA_NO_CRT)
/* For private key operations, use D or DP & DQ
* as (unblinded) exponents. */
if( is_priv && mbedtls_mpi_cmp_int( &ctx->D, 0 ) <= 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
#else
if( is_priv &&
( mbedtls_mpi_cmp_int( &ctx->DP, 0 ) <= 0 ||
mbedtls_mpi_cmp_int( &ctx->DQ, 0 ) <= 0 ) )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#endif /* MBEDTLS_RSA_NO_CRT */
/* Blinding shouldn't make exponents negative either,
* so check that P, Q >= 1 if that hasn't yet been
* done as part of 1. */
#if defined(MBEDTLS_RSA_NO_CRT)
if( is_priv && blinding_needed &&
( mbedtls_mpi_cmp_int( &ctx->P, 0 ) <= 0 ||
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) <= 0 ) )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#endif
/* It wouldn't lead to an error if it wasn't satisfied,
* but check for QP >= 1 nonetheless. */
#if !defined(MBEDTLS_RSA_NO_CRT)
if( is_priv &&
mbedtls_mpi_cmp_int( &ctx->QP, 0 ) <= 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#endif
return( 0 );
}
int mbedtls_rsa_complete( mbedtls_rsa_context *ctx )
{
int ret = 0;
const int have_N = ( mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 );
const int have_P = ( mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 );
const int have_Q = ( mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 );
const int have_D = ( mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 );
const int have_E = ( mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0 );
/*
* Check whether provided parameters are enough
* to deduce all others. The following incomplete
* parameter sets for private keys are supported:
*
* (1) P, Q missing.
* (2) D and potentially N missing.
*
*/
const int n_missing = have_P && have_Q && have_D && have_E;
const int pq_missing = have_N && !have_P && !have_Q && have_D && have_E;
const int d_missing = have_P && have_Q && !have_D && have_E;
const int is_pub = have_N && !have_P && !have_Q && !have_D && have_E;
/* These three alternatives are mutually exclusive */
const int is_priv = n_missing || pq_missing || d_missing;
if( !is_priv && !is_pub )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
* Step 1: Deduce N if P, Q are provided.
*/
if( !have_N && have_P && have_Q )
{
if( ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P,
&ctx->Q ) ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
ctx->len = mbedtls_mpi_size( &ctx->N );
}
/*
* Step 2: Deduce and verify all remaining core parameters.
*/
if( pq_missing )
{
ret = mbedtls_rsa_deduce_primes( &ctx->N, &ctx->E, &ctx->D,
&ctx->P, &ctx->Q );
if( ret != 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
else if( d_missing )
{
if( ( ret = mbedtls_rsa_deduce_private_exponent( &ctx->P,
&ctx->Q,
&ctx->E,
&ctx->D ) ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
}
/*
* Step 3: Deduce all additional parameters specific
* to our current RSA implementation.
*/
#if !defined(MBEDTLS_RSA_NO_CRT)
if( is_priv )
{
ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D,
&ctx->DP, &ctx->DQ, &ctx->QP );
if( ret != 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
#endif /* MBEDTLS_RSA_NO_CRT */
/*
* Step 3: Basic sanity checks
*/
return( rsa_check_context( ctx, is_priv, 1 ) );
}
int mbedtls_rsa_export_raw( const mbedtls_rsa_context *ctx,
unsigned char *N, size_t N_len,
unsigned char *P, size_t P_len,
unsigned char *Q, size_t Q_len,
unsigned char *D, size_t D_len,
unsigned char *E, size_t E_len )
{
int ret = 0;
/* Check if key is private or public */
const int is_priv =
mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0;
if( !is_priv )
{
/* If we're trying to export private parameters for a public key,
* something must be wrong. */
if( P != NULL || Q != NULL || D != NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
if( N != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->N, N, N_len ) );
if( P != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->P, P, P_len ) );
if( Q != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->Q, Q, Q_len ) );
if( D != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->D, D, D_len ) );
if( E != NULL )
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->E, E, E_len ) );
cleanup:
return( ret );
}
int mbedtls_rsa_export( const mbedtls_rsa_context *ctx,
mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q,
mbedtls_mpi *D, mbedtls_mpi *E )
{
int ret;
/* Check if key is private or public */
int is_priv =
mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0;
if( !is_priv )
{
/* If we're trying to export private parameters for a public key,
* something must be wrong. */
if( P != NULL || Q != NULL || D != NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
/* Export all requested core parameters. */
if( ( N != NULL && ( ret = mbedtls_mpi_copy( N, &ctx->N ) ) != 0 ) ||
( P != NULL && ( ret = mbedtls_mpi_copy( P, &ctx->P ) ) != 0 ) ||
( Q != NULL && ( ret = mbedtls_mpi_copy( Q, &ctx->Q ) ) != 0 ) ||
( D != NULL && ( ret = mbedtls_mpi_copy( D, &ctx->D ) ) != 0 ) ||
( E != NULL && ( ret = mbedtls_mpi_copy( E, &ctx->E ) ) != 0 ) )
{
return( ret );
}
return( 0 );
}
/*
* Export CRT parameters
* This must also be implemented if CRT is not used, for being able to
* write DER encoded RSA keys. The helper function mbedtls_rsa_deduce_crt
* can be used in this case.
*/
int mbedtls_rsa_export_crt( const mbedtls_rsa_context *ctx,
mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP )
{
int ret;
/* Check if key is private or public */
int is_priv =
mbedtls_mpi_cmp_int( &ctx->N, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->P, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->Q, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->D, 0 ) != 0 &&
mbedtls_mpi_cmp_int( &ctx->E, 0 ) != 0;
if( !is_priv )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
#if !defined(MBEDTLS_RSA_NO_CRT)
/* Export all requested blinding parameters. */
if( ( DP != NULL && ( ret = mbedtls_mpi_copy( DP, &ctx->DP ) ) != 0 ) ||
( DQ != NULL && ( ret = mbedtls_mpi_copy( DQ, &ctx->DQ ) ) != 0 ) ||
( QP != NULL && ( ret = mbedtls_mpi_copy( QP, &ctx->QP ) ) != 0 ) )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
#else
if( ( ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D,
DP, DQ, QP ) ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
}
#endif
return( 0 );
}
/*
* Initialize an RSA context
*/
void mbedtls_rsa_init( mbedtls_rsa_context *ctx,
int padding,
int hash_id )
{
memset( ctx, 0, sizeof( mbedtls_rsa_context ) );
mbedtls_rsa_set_padding( ctx, padding, hash_id );
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &ctx->mutex );
#endif
}
/*
* Set padding for an existing RSA context
*/
void mbedtls_rsa_set_padding( mbedtls_rsa_context *ctx, int padding, int hash_id )
{
ctx->padding = padding;
ctx->hash_id = hash_id;
}
/*
* Get length in bytes of RSA modulus
*/
size_t mbedtls_rsa_get_len( const mbedtls_rsa_context *ctx )
{
return( ctx->len );
}
#if defined(MBEDTLS_GENPRIME)
/*
* Generate an RSA keypair
*/
int mbedtls_rsa_gen_key( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
unsigned int nbits, int exponent )
{
int ret;
mbedtls_mpi H, G;
if( f_rng == NULL || nbits < 128 || exponent < 3 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
if( nbits % 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &H );
mbedtls_mpi_init( &G );
/*
* find primes P and Q with Q < P so that:
* GCD( E, (P-1)*(Q-1) ) == 1
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->E, exponent ) );
do
{
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->P, nbits >> 1, 0,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gen_prime( &ctx->Q, nbits >> 1, 0,
f_rng, p_rng ) );
if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) == 0 )
continue;
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P, &ctx->Q ) );
if( mbedtls_mpi_bitlen( &ctx->N ) != nbits )
continue;
if( mbedtls_mpi_cmp_mpi( &ctx->P, &ctx->Q ) < 0 )
mbedtls_mpi_swap( &ctx->P, &ctx->Q );
/* Temporarily replace P,Q by P-1, Q-1 */
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->P, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &ctx->Q, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &ctx->P, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) );
}
while( mbedtls_mpi_cmp_int( &G, 1 ) != 0 );
/* Restore P,Q */
MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->P, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_int( &ctx->Q, &ctx->Q, 1 ) );
ctx->len = mbedtls_mpi_size( &ctx->N );
/*
* D = E^-1 mod ((P-1)*(Q-1))
* DP = D mod (P - 1)
* DQ = D mod (Q - 1)
* QP = Q^-1 mod P
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->D, &ctx->E, &H ) );
#if !defined(MBEDTLS_RSA_NO_CRT)
MBEDTLS_MPI_CHK( mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D,
&ctx->DP, &ctx->DQ, &ctx->QP ) );
#endif /* MBEDTLS_RSA_NO_CRT */
/* Double-check */
MBEDTLS_MPI_CHK( mbedtls_rsa_check_privkey( ctx ) );
cleanup:
mbedtls_mpi_free( &H );
mbedtls_mpi_free( &G );
if( ret != 0 )
{
mbedtls_rsa_free( ctx );
return( MBEDTLS_ERR_RSA_KEY_GEN_FAILED + ret );
}
return( 0 );
}
#endif /* MBEDTLS_GENPRIME */
/*
* Check a public RSA key
*/
int mbedtls_rsa_check_pubkey( const mbedtls_rsa_context *ctx )
{
if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) != 0 )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
if( mbedtls_mpi_bitlen( &ctx->N ) < 128 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
if( mbedtls_mpi_get_bit( &ctx->E, 0 ) == 0 ||
mbedtls_mpi_bitlen( &ctx->E ) < 2 ||
mbedtls_mpi_cmp_mpi( &ctx->E, &ctx->N ) >= 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
return( 0 );
}
/*
* Check for the consistency of all fields in an RSA private key context
*/
int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx )
{
if( mbedtls_rsa_check_pubkey( ctx ) != 0 ||
rsa_check_context( ctx, 1 /* private */, 1 /* blinding */ ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
if( mbedtls_rsa_validate_params( &ctx->N, &ctx->P, &ctx->Q,
&ctx->D, &ctx->E, NULL, NULL ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
#if !defined(MBEDTLS_RSA_NO_CRT)
else if( mbedtls_rsa_validate_crt( &ctx->P, &ctx->Q, &ctx->D,
&ctx->DP, &ctx->DQ, &ctx->QP ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
#endif
return( 0 );
}
/*
* Check if contexts holding a public and private key match
*/
int mbedtls_rsa_check_pub_priv( const mbedtls_rsa_context *pub,
const mbedtls_rsa_context *prv )
{
if( mbedtls_rsa_check_pubkey( pub ) != 0 ||
mbedtls_rsa_check_privkey( prv ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
if( mbedtls_mpi_cmp_mpi( &pub->N, &prv->N ) != 0 ||
mbedtls_mpi_cmp_mpi( &pub->E, &prv->E ) != 0 )
{
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
}
return( 0 );
}
/*
* Do an RSA public key operation
*/
int mbedtls_rsa_public( mbedtls_rsa_context *ctx,
const unsigned char *input,
unsigned char *output )
{
int ret;
size_t olen;
mbedtls_mpi T;
if( rsa_check_context( ctx, 0 /* public */, 0 /* no blinding */ ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &T );
#if defined(MBEDTLS_THREADING_C)
if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) );
if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
{
ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
goto cleanup;
}
olen = ctx->len;
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, &ctx->E, &ctx->N, &ctx->RN ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) );
cleanup:
#if defined(MBEDTLS_THREADING_C)
if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
#endif
mbedtls_mpi_free( &T );
if( ret != 0 )
return( MBEDTLS_ERR_RSA_PUBLIC_FAILED + ret );
return( 0 );
}
/*
* Generate or update blinding values, see section 10 of:
* KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
* DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer
* Berlin Heidelberg, 1996. p. 104-113.
*/
static int rsa_prepare_blinding( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
int ret, count = 0;
if( ctx->Vf.p != NULL )
{
/* We already have blinding values, just update them by squaring */
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->N ) );
goto cleanup;
}
/* Unblinding value: Vf = random number, invertible mod N */
do {
if( count++ > 10 )
return( MBEDTLS_ERR_RSA_RNG_FAILED );
MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &ctx->Vf, ctx->len - 1, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &ctx->Vi, &ctx->Vf, &ctx->N ) );
} while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) != 0 );
/* Blinding value: Vi = Vf^(-e) mod N */
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vi, &ctx->Vf, &ctx->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN ) );
cleanup:
return( ret );
}
/*
* Exponent blinding supposed to prevent side-channel attacks using multiple
* traces of measurements to recover the RSA key. The more collisions are there,
* the more bits of the key can be recovered. See [3].
*
* Collecting n collisions with m bit long blinding value requires 2^(m-m/n)
* observations on avarage.
*
* For example with 28 byte blinding to achieve 2 collisions the adversary has
* to make 2^112 observations on avarage.
*
* (With the currently (as of 2017 April) known best algorithms breaking 2048
* bit RSA requires approximately as much time as trying out 2^112 random keys.
* Thus in this sense with 28 byte blinding the security is not reduced by
* side-channel attacks like the one in [3])
*
* This countermeasure does not help if the key recovery is possible with a
* single trace.
*/
#define RSA_EXPONENT_BLINDING 28
/*
* Do an RSA private key operation
*/
int mbedtls_rsa_private( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
const unsigned char *input,
unsigned char *output )
{
int ret;
size_t olen;
/* Temporary holding the result */
mbedtls_mpi T;
/* Temporaries holding P-1, Q-1 and the
* exponent blinding factor, respectively. */
mbedtls_mpi P1, Q1, R;
#if !defined(MBEDTLS_RSA_NO_CRT)
/* Temporaries holding the results mod p resp. mod q. */
mbedtls_mpi TP, TQ;
/* Temporaries holding the blinded exponents for
* the mod p resp. mod q computation (if used). */
mbedtls_mpi DP_blind, DQ_blind;
/* Pointers to actual exponents to be used - either the unblinded
* or the blinded ones, depending on the presence of a PRNG. */
mbedtls_mpi *DP = &ctx->DP;
mbedtls_mpi *DQ = &ctx->DQ;
#else
/* Temporary holding the blinded exponent (if used). */
mbedtls_mpi D_blind;
/* Pointer to actual exponent to be used - either the unblinded
* or the blinded one, depending on the presence of a PRNG. */
mbedtls_mpi *D = &ctx->D;
#endif /* MBEDTLS_RSA_NO_CRT */
/* Temporaries holding the initial input and the double
* checked result; should be the same in the end. */
mbedtls_mpi I, C;
if( rsa_check_context( ctx, 1 /* private key checks */,
f_rng != NULL /* blinding y/n */ ) != 0 )
{
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
#if defined(MBEDTLS_THREADING_C)
if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
return( ret );
#endif
/* MPI Initialization */
mbedtls_mpi_init( &T );
mbedtls_mpi_init( &P1 );
mbedtls_mpi_init( &Q1 );
mbedtls_mpi_init( &R );
if( f_rng != NULL )
{
#if defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_init( &D_blind );
#else
mbedtls_mpi_init( &DP_blind );
mbedtls_mpi_init( &DQ_blind );
#endif
}
#if !defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_init( &TP ); mbedtls_mpi_init( &TQ );
#endif
mbedtls_mpi_init( &I );
mbedtls_mpi_init( &C );
/* End of MPI initialization */
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &T, input, ctx->len ) );
if( mbedtls_mpi_cmp_mpi( &T, &ctx->N ) >= 0 )
{
ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
goto cleanup;
}
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &I, &T ) );
if( f_rng != NULL )
{
/*
* Blinding
* T = T * Vi mod N
*/
MBEDTLS_MPI_CHK( rsa_prepare_blinding( ctx, f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vi ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) );
/*
* Exponent blinding
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
#if defined(MBEDTLS_RSA_NO_CRT)
/*
* D_blind = ( P - 1 ) * ( Q - 1 ) * R + D
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &D_blind, &D_blind, &R ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &D_blind, &D_blind, &ctx->D ) );
D = &D_blind;
#else
/*
* DP_blind = ( P - 1 ) * R + DP
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DP_blind, &P1, &R ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DP_blind, &DP_blind,
&ctx->DP ) );
DP = &DP_blind;
/*
* DQ_blind = ( Q - 1 ) * R + DQ
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &R, RSA_EXPONENT_BLINDING,
f_rng, p_rng ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DQ_blind, &Q1, &R ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &DQ_blind, &DQ_blind,
&ctx->DQ ) );
DQ = &DQ_blind;
#endif /* MBEDTLS_RSA_NO_CRT */
}
#if defined(MBEDTLS_RSA_NO_CRT)
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T, &T, D, &ctx->N, &ctx->RN ) );
#else
/*
* Faster decryption using the CRT
*
* TP = input ^ dP mod P
* TQ = input ^ dQ mod Q
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TP, &T, DP, &ctx->P, &ctx->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &TQ, &T, DQ, &ctx->Q, &ctx->RQ ) );
/*
* T = (TP - TQ) * (Q^-1 mod P) mod P
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &TP, &TQ ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->QP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &TP, &ctx->P ) );
/*
* T = TQ + T * Q
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &TP, &T, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &TQ, &TP ) );
#endif /* MBEDTLS_RSA_NO_CRT */
if( f_rng != NULL )
{
/*
* Unblind
* T = T * Vf mod N
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T, &T, &ctx->Vf ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T, &ctx->N ) );
}
/* Verify the result to prevent glitching attacks. */
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &C, &T, &ctx->E,
&ctx->N, &ctx->RN ) );
if( mbedtls_mpi_cmp_mpi( &C, &I ) != 0 )
{
ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
goto cleanup;
}
olen = ctx->len;
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &T, output, olen ) );
cleanup:
#if defined(MBEDTLS_THREADING_C)
if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
#endif
mbedtls_mpi_free( &P1 );
mbedtls_mpi_free( &Q1 );
mbedtls_mpi_free( &R );
if( f_rng != NULL )
{
#if defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_free( &D_blind );
#else
mbedtls_mpi_free( &DP_blind );
mbedtls_mpi_free( &DQ_blind );
#endif
}
mbedtls_mpi_free( &T );
#if !defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_free( &TP ); mbedtls_mpi_free( &TQ );
#endif
mbedtls_mpi_free( &C );
mbedtls_mpi_free( &I );
if( ret != 0 )
return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret );
return( 0 );
}
#if defined(MBEDTLS_PKCS1_V21)
/**
* Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer.
*
* \param dst buffer to mask
* \param dlen length of destination buffer
* \param src source of the mask generation
* \param slen length of the source buffer
* \param md_ctx message digest context to use
*/
static int mgf_mask( unsigned char *dst, size_t dlen, unsigned char *src,
size_t slen, mbedtls_md_context_t *md_ctx )
{
unsigned char mask[MBEDTLS_MD_MAX_SIZE];
unsigned char counter[4];
unsigned char *p;
unsigned int hlen;
size_t i, use_len;
int ret = 0;
memset( mask, 0, MBEDTLS_MD_MAX_SIZE );
memset( counter, 0, 4 );
hlen = mbedtls_md_get_size( md_ctx->md_info );
/* Generate and apply dbMask */
p = dst;
while( dlen > 0 )
{
use_len = hlen;
if( dlen < hlen )
use_len = dlen;
if( ( ret = mbedtls_md_starts( md_ctx ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_update( md_ctx, src, slen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_update( md_ctx, counter, 4 ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_finish( md_ctx, mask ) ) != 0 )
goto exit;
for( i = 0; i < use_len; ++i )
*p++ ^= mask[i];
counter[3]++;
dlen -= use_len;
}
exit:
mbedtls_zeroize( mask, sizeof( mask ) );
return( ret );
}
#endif /* MBEDTLS_PKCS1_V21 */
#if defined(MBEDTLS_PKCS1_V21)
/*
* Implementation of the PKCS#1 v2.1 RSAES-OAEP-ENCRYPT function
*/
int mbedtls_rsa_rsaes_oaep_encrypt( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
const unsigned char *label, size_t label_len,
size_t ilen,
const unsigned char *input,
unsigned char *output )
{
size_t olen;
int ret;
unsigned char *p = output;
unsigned int hlen;
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
if( f_rng == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
olen = ctx->len;
hlen = mbedtls_md_get_size( md_info );
/* first comparison checks for overflow */
if( ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
memset( output, 0, olen );
*p++ = 0;
/* Generate a random octet string seed */
if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 )
return( MBEDTLS_ERR_RSA_RNG_FAILED + ret );
p += hlen;
/* Construct DB */
if( ( ret = mbedtls_md( md_info, label, label_len, p ) ) != 0 )
return( ret );
p += hlen;
p += olen - 2 * hlen - 2 - ilen;
*p++ = 1;
memcpy( p, input, ilen );
mbedtls_md_init( &md_ctx );
if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
goto exit;
/* maskedDB: Apply dbMask to DB */
if( ( ret = mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen,
&md_ctx ) ) != 0 )
goto exit;
/* maskedSeed: Apply seedMask to seed */
if( ( ret = mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1,
&md_ctx ) ) != 0 )
goto exit;
exit:
mbedtls_md_free( &md_ctx );
if( ret != 0 )
return( ret );
return( ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, output, output )
: mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) );
}
#endif /* MBEDTLS_PKCS1_V21 */
#if defined(MBEDTLS_PKCS1_V15)
/*
* Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-ENCRYPT function
*/
int mbedtls_rsa_rsaes_pkcs1_v15_encrypt( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode, size_t ilen,
const unsigned char *input,
unsigned char *output )
{
size_t nb_pad, olen;
int ret;
unsigned char *p = output;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
// We don't check p_rng because it won't be dereferenced here
if( f_rng == NULL || input == NULL || output == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
olen = ctx->len;
/* first comparison checks for overflow */
if( ilen + 11 < ilen || olen < ilen + 11 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
nb_pad = olen - 3 - ilen;
*p++ = 0;
if( mode == MBEDTLS_RSA_PUBLIC )
{
*p++ = MBEDTLS_RSA_CRYPT;
while( nb_pad-- > 0 )
{
int rng_dl = 100;
do {
ret = f_rng( p_rng, p, 1 );
} while( *p == 0 && --rng_dl && ret == 0 );
/* Check if RNG failed to generate data */
if( rng_dl == 0 || ret != 0 )
return( MBEDTLS_ERR_RSA_RNG_FAILED + ret );
p++;
}
}
else
{
*p++ = MBEDTLS_RSA_SIGN;
while( nb_pad-- > 0 )
*p++ = 0xFF;
}
*p++ = 0;
memcpy( p, input, ilen );
return( ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, output, output )
: mbedtls_rsa_private( ctx, f_rng, p_rng, output, output ) );
}
#endif /* MBEDTLS_PKCS1_V15 */
/*
* Add the message padding, then do an RSA operation
*/
int mbedtls_rsa_pkcs1_encrypt( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode, size_t ilen,
const unsigned char *input,
unsigned char *output )
{
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
case MBEDTLS_RSA_PKCS_V15:
return mbedtls_rsa_rsaes_pkcs1_v15_encrypt( ctx, f_rng, p_rng, mode, ilen,
input, output );
#endif
#if defined(MBEDTLS_PKCS1_V21)
case MBEDTLS_RSA_PKCS_V21:
return mbedtls_rsa_rsaes_oaep_encrypt( ctx, f_rng, p_rng, mode, NULL, 0,
ilen, input, output );
#endif
default:
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
}
}
#if defined(MBEDTLS_PKCS1_V21)
/*
* Implementation of the PKCS#1 v2.1 RSAES-OAEP-DECRYPT function
*/
int mbedtls_rsa_rsaes_oaep_decrypt( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
const unsigned char *label, size_t label_len,
size_t *olen,
const unsigned char *input,
unsigned char *output,
size_t output_max_len )
{
int ret;
size_t ilen, i, pad_len;
unsigned char *p, bad, pad_done;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
unsigned char lhash[MBEDTLS_MD_MAX_SIZE];
unsigned int hlen;
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
/*
* Parameters sanity checks
*/
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
ilen = ctx->len;
if( ilen < 16 || ilen > sizeof( buf ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hlen = mbedtls_md_get_size( md_info );
// checking for integer underflow
if( 2 * hlen + 2 > ilen )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
* RSA operation
*/
ret = ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, input, buf )
: mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf );
if( ret != 0 )
goto cleanup;
/*
* Unmask data and generate lHash
*/
mbedtls_md_init( &md_ctx );
if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
{
mbedtls_md_free( &md_ctx );
goto cleanup;
}
/* seed: Apply seedMask to maskedSeed */
if( ( ret = mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
&md_ctx ) ) != 0 ||
/* DB: Apply dbMask to maskedDB */
( ret = mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
&md_ctx ) ) != 0 )
{
mbedtls_md_free( &md_ctx );
goto cleanup;
}
mbedtls_md_free( &md_ctx );
/* Generate lHash */
if( ( ret = mbedtls_md( md_info, label, label_len, lhash ) ) != 0 )
goto cleanup;
/*
* Check contents, in "constant-time"
*/
p = buf;
bad = 0;
bad |= *p++; /* First byte must be 0 */
p += hlen; /* Skip seed */
/* Check lHash */
for( i = 0; i < hlen; i++ )
bad |= lhash[i] ^ *p++;
/* Get zero-padding len, but always read till end of buffer
* (minus one, for the 01 byte) */
pad_len = 0;
pad_done = 0;
for( i = 0; i < ilen - 2 * hlen - 2; i++ )
{
pad_done |= p[i];
pad_len += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
}
p += pad_len;
bad |= *p++ ^ 0x01;
/*
* The only information "leaked" is whether the padding was correct or not
* (eg, no data is copied if it was not correct). This meets the
* recommendations in PKCS#1 v2.2: an opponent cannot distinguish between
* the different error conditions.
*/
if( bad != 0 )
{
ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
goto cleanup;
}
if( ilen - ( p - buf ) > output_max_len )
{
ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE;
goto cleanup;
}
*olen = ilen - (p - buf);
memcpy( output, p, *olen );
ret = 0;
cleanup:
mbedtls_zeroize( buf, sizeof( buf ) );
mbedtls_zeroize( lhash, sizeof( lhash ) );
return( ret );
}
#endif /* MBEDTLS_PKCS1_V21 */
#if defined(MBEDTLS_PKCS1_V15)
/** Turn zero-or-nonzero into zero-or-all-bits-one, without branches.
*
* \param value The value to analyze.
* \return Zero if \p value is zero, otherwise all-bits-one.
*/
static unsigned all_or_nothing_int( unsigned value )
{
/* MSVC has a warning about unary minus on unsigned, but this is
* well-defined and precisely what we want to do here */
#if defined(_MSC_VER)
#pragma warning( push )
#pragma warning( disable : 4146 )
#endif
return( - ( ( value | - value ) >> ( sizeof( value ) * 8 - 1 ) ) );
#if defined(_MSC_VER)
#pragma warning( pop )
#endif
}
/** Check whether a size is out of bounds, without branches.
*
* This is equivalent to `size > max`, but is likely to be compiled to
* to code using bitwise operation rather than a branch.
*
* \param size Size to check.
* \param max Maximum desired value for \p size.
* \return \c 0 if `size <= max`.
* \return \c 1 if `size > max`.
*/
static unsigned size_greater_than( size_t size, size_t max )
{
/* Return the sign bit (1 for negative) of (max - size). */
return( ( max - size ) >> ( sizeof( size_t ) * 8 - 1 ) );
}
/** Choose between two integer values, without branches.
*
* This is equivalent to `cond ? if1 : if0`, but is likely to be compiled
* to code using bitwise operation rather than a branch.
*
* \param cond Condition to test.
* \param if1 Value to use if \p cond is nonzero.
* \param if0 Value to use if \p cond is zero.
* \return \c if1 if \p cond is nonzero, otherwise \c if0.
*/
static unsigned if_int( unsigned cond, unsigned if1, unsigned if0 )
{
unsigned mask = all_or_nothing_int( cond );
return( ( mask & if1 ) | (~mask & if0 ) );
}
/** Shift some data towards the left inside a buffer without leaking
* the length of the data through side channels.
*
* `mem_move_to_left(start, total, offset)` is functionally equivalent to
* ```
* memmove(start, start + offset, total - offset);
* memset(start + offset, 0, total - offset);
* ```
* but it strives to use a memory access pattern (and thus total timing)
* that does not depend on \p offset. This timing independence comes at
* the expense of performance.
*
* \param start Pointer to the start of the buffer.
* \param total Total size of the buffer.
* \param offset Offset from which to copy \p total - \p offset bytes.
*/
static void mem_move_to_left( void *start,
size_t total,
size_t offset )
{
volatile unsigned char *buf = start;
size_t i, n;
if( total == 0 )
return;
for( i = 0; i < total; i++ )
{
unsigned no_op = size_greater_than( total - offset, i );
/* The first `total - offset` passes are a no-op. The last
* `offset` passes shift the data one byte to the left and
* zero out the last byte. */
for( n = 0; n < total - 1; n++ )
buf[n] = if_int( no_op, buf[n], buf[n+1] );
buf[total-1] = if_int( no_op, buf[total-1], 0 );
}
}
/*
* Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function
*/
int mbedtls_rsa_rsaes_pkcs1_v15_decrypt( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode, size_t *olen,
const unsigned char *input,
unsigned char *output,
size_t output_max_len )
{
int ret;
size_t ilen = ctx->len;
size_t i;
size_t plaintext_max_size = ( output_max_len > ilen - 11 ?
ilen - 11 :
output_max_len );
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
/* The following variables take sensitive values: their value must
* not leak into the observable behavior of the function other than
* the designated outputs (output, olen, return value). Otherwise
* this would open the execution of the function to
* side-channel-based variants of the Bleichenbacher padding oracle
* attack. Potential side channels include overall timing, memory
* access patterns (especially visible to an adversary who has access
* to a shared memory cache), and branches (especially visible to
* an adversary who has access to a shared code cache or to a shared
* branch predictor). */
size_t pad_count = 0;
unsigned bad = 0;
unsigned char pad_done = 0;
size_t plaintext_size = 0;
unsigned output_too_large;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
if( ilen < 16 || ilen > sizeof( buf ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
ret = ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, input, buf )
: mbedtls_rsa_private( ctx, f_rng, p_rng, input, buf );
if( ret != 0 )
goto cleanup;
/*
* Check and get padding len in "constant-time"
*/
bad |= buf[0]; /* First byte must be 0 */
/* This test does not depend on secret data */
if( mode == MBEDTLS_RSA_PRIVATE )
{
bad |= buf[1] ^ MBEDTLS_RSA_CRYPT;
/* Get padding len, but always read till end of buffer
* (minus one, for the 00 byte) */
for( i = 2; i < ilen - 1; i++ )
{
pad_done |= ((buf[i] | (unsigned char)-buf[i]) >> 7) ^ 1;
pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
}
bad |= buf[pad_count + 2];
}
else
{
bad |= buf[1] ^ MBEDTLS_RSA_SIGN;
/* Get padding len, but always read till end of buffer
* (minus one, for the 00 byte) */
for( i = 2; i < ilen - 1; i++ )
{
pad_done |= ( buf[i] != 0xFF );
pad_count += ( pad_done == 0 );
}
bad |= buf[pad_count + 2];
}
/* There must be at least 8 bytes of padding. */
bad |= size_greater_than( 8, pad_count );
/* If the padding is valid, set plaintext_size to the number of
* remaining bytes after stripping the padding. If the padding
* is invalid, avoid leaking this fact through the size of the
* output: use the maximum message size that fits in the output
* buffer. Do it without branches to avoid leaking the padding
* validity through timing. RSA keys are small enough that all the
* size_t values involved fit in unsigned int. */
plaintext_size = if_int( bad,
(unsigned) plaintext_max_size,
(unsigned) ( ilen - pad_count - 3 ) );
/* Set output_too_large to 0 if the plaintext fits in the output
* buffer and to 1 otherwise. */
output_too_large = size_greater_than( plaintext_size,
plaintext_max_size );
/* Set ret without branches to avoid timing attacks. Return:
* - INVALID_PADDING if the padding is bad (bad != 0).
* - OUTPUT_TOO_LARGE if the padding is good but the decrypted
* plaintext does not fit in the output buffer.
* - 0 if the padding is correct. */
ret = - if_int( bad, - MBEDTLS_ERR_RSA_INVALID_PADDING,
if_int( output_too_large, - MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE,
0 ) );
/* If the padding is bad or the plaintext is too large, zero the
* data that we're about to copy to the output buffer.
* We need to copy the same amount of data
* from the same buffer whether the padding is good or not to
* avoid leaking the padding validity through overall timing or
* through memory or cache access patterns. */
for( i = 11; i < ilen; i++ )
buf[i] &= ~( bad | output_too_large );
/* If the plaintext is too large, truncate it to the buffer size.
* Copy anyway to avoid revealing the length through timing, because
* revealing the length is as bad as revealing the padding validity
* for a Bleichenbacher attack. */
plaintext_size = if_int( output_too_large,
(unsigned) plaintext_max_size,
(unsigned) plaintext_size );
/* Move the plaintext to the leftmost position where it can start in
* the working buffer, i.e. make it start plaintext_max_size from
* the end of the buffer. Do this with a memory access trace that
* does not depend on the plaintext size. After this move, the
* starting location of the plaintext is no longer sensitive
* information. */
mem_move_to_left( buf + ilen - plaintext_max_size,
plaintext_max_size,
plaintext_max_size - plaintext_size );
/* Finally copy the decrypted plaintext plus trailing zeros
* into the output buffer. */
memcpy( output, buf + ilen - plaintext_max_size, plaintext_max_size );
/* Report the amount of data we copied to the output buffer. In case
* of errors (bad padding or output too large), the value of *olen
* when this function returns is not specified. Making it equivalent
* to the good case limits the risks of leaking the padding validity. */
*olen = plaintext_size;
cleanup:
mbedtls_zeroize( buf, sizeof( buf ) );
return( ret );
}
#endif /* MBEDTLS_PKCS1_V15 */
/*
* Do an RSA operation, then remove the message padding
*/
int mbedtls_rsa_pkcs1_decrypt( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode, size_t *olen,
const unsigned char *input,
unsigned char *output,
size_t output_max_len)
{
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
case MBEDTLS_RSA_PKCS_V15:
return mbedtls_rsa_rsaes_pkcs1_v15_decrypt( ctx, f_rng, p_rng, mode, olen,
input, output, output_max_len );
#endif
#if defined(MBEDTLS_PKCS1_V21)
case MBEDTLS_RSA_PKCS_V21:
return mbedtls_rsa_rsaes_oaep_decrypt( ctx, f_rng, p_rng, mode, NULL, 0,
olen, input, output,
output_max_len );
#endif
default:
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
}
}
#if defined(MBEDTLS_PKCS1_V21)
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function
*/
int mbedtls_rsa_rsassa_pss_sign( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig )
{
size_t olen;
unsigned char *p = sig;
unsigned char salt[MBEDTLS_MD_MAX_SIZE];
unsigned int slen, hlen, offset = 0;
int ret;
size_t msb;
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
if( f_rng == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
olen = ctx->len;
if( md_alg != MBEDTLS_MD_NONE )
{
/* Gather length of hash to sign */
md_info = mbedtls_md_info_from_type( md_alg );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hashlen = mbedtls_md_get_size( md_info );
}
md_info = mbedtls_md_info_from_type( (mbedtls_md_type_t) ctx->hash_id );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hlen = mbedtls_md_get_size( md_info );
slen = hlen;
if( olen < hlen + slen + 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
memset( sig, 0, olen );
/* Generate salt of length slen */
if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 )
return( MBEDTLS_ERR_RSA_RNG_FAILED + ret );
/* Note: EMSA-PSS encoding is over the length of N - 1 bits */
msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
p += olen - hlen * 2 - 2;
*p++ = 0x01;
memcpy( p, salt, slen );
p += slen;
mbedtls_md_init( &md_ctx );
if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
goto exit;
/* Generate H = Hash( M' ) */
if( ( ret = mbedtls_md_starts( &md_ctx ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_update( &md_ctx, p, 8 ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_update( &md_ctx, hash, hashlen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_update( &md_ctx, salt, slen ) ) != 0 )
goto exit;
if( ( ret = mbedtls_md_finish( &md_ctx, p ) ) != 0 )
goto exit;
/* Compensate for boundary condition when applying mask */
if( msb % 8 == 0 )
offset = 1;
/* maskedDB: Apply dbMask to DB */
if( ( ret = mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen,
&md_ctx ) ) != 0 )
goto exit;
msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
sig[0] &= 0xFF >> ( olen * 8 - msb );
p += hlen;
*p++ = 0xBC;
mbedtls_zeroize( salt, sizeof( salt ) );
exit:
mbedtls_md_free( &md_ctx );
if( ret != 0 )
return( ret );
return( ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, sig, sig )
: mbedtls_rsa_private( ctx, f_rng, p_rng, sig, sig ) );
}
#endif /* MBEDTLS_PKCS1_V21 */
#if defined(MBEDTLS_PKCS1_V15)
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function
*/
/* Construct a PKCS v1.5 encoding of a hashed message
*
* This is used both for signature generation and verification.
*
* Parameters:
* - md_alg: Identifies the hash algorithm used to generate the given hash;
* MBEDTLS_MD_NONE if raw data is signed.
* - hashlen: Length of hash in case hashlen is MBEDTLS_MD_NONE.
* - hash: Buffer containing the hashed message or the raw data.
* - dst_len: Length of the encoded message.
* - dst: Buffer to hold the encoded message.
*
* Assumptions:
* - hash has size hashlen if md_alg == MBEDTLS_MD_NONE.
* - hash has size corresponding to md_alg if md_alg != MBEDTLS_MD_NONE.
* - dst points to a buffer of size at least dst_len.
*
*/
static int rsa_rsassa_pkcs1_v15_encode( mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
size_t dst_len,
unsigned char *dst )
{
size_t oid_size = 0;
size_t nb_pad = dst_len;
unsigned char *p = dst;
const char *oid = NULL;
/* Are we signing hashed or raw data? */
if( md_alg != MBEDTLS_MD_NONE )
{
const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
if( mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size ) != 0 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hashlen = mbedtls_md_get_size( md_info );
/* Double-check that 8 + hashlen + oid_size can be used as a
* 1-byte ASN.1 length encoding and that there's no overflow. */
if( 8 + hashlen + oid_size >= 0x80 ||
10 + hashlen < hashlen ||
10 + hashlen + oid_size < 10 + hashlen )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
* Static bounds check:
* - Need 10 bytes for five tag-length pairs.
* (Insist on 1-byte length encodings to protect against variants of
* Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification)
* - Need hashlen bytes for hash
* - Need oid_size bytes for hash alg OID.
*/
if( nb_pad < 10 + hashlen + oid_size )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
nb_pad -= 10 + hashlen + oid_size;
}
else
{
if( nb_pad < hashlen )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
nb_pad -= hashlen;
}
/* Need space for signature header and padding delimiter (3 bytes),
* and 8 bytes for the minimal padding */
if( nb_pad < 3 + 8 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
nb_pad -= 3;
/* Now nb_pad is the amount of memory to be filled
* with padding, and at least 8 bytes long. */
/* Write signature header and padding */
*p++ = 0;
*p++ = MBEDTLS_RSA_SIGN;
memset( p, 0xFF, nb_pad );
p += nb_pad;
*p++ = 0;
/* Are we signing raw data? */
if( md_alg == MBEDTLS_MD_NONE )
{
memcpy( p, hash, hashlen );
return( 0 );
}
/* Signing hashed data, add corresponding ASN.1 structure
*
* DigestInfo ::= SEQUENCE {
* digestAlgorithm DigestAlgorithmIdentifier,
* digest Digest }
* DigestAlgorithmIdentifier ::= AlgorithmIdentifier
* Digest ::= OCTET STRING
*
* Schematic:
* TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID + LEN [ OID ]
* TAG-NULL + LEN [ NULL ] ]
* TAG-OCTET + LEN [ HASH ] ]
*/
*p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
*p++ = (unsigned char)( 0x08 + oid_size + hashlen );
*p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
*p++ = (unsigned char)( 0x04 + oid_size );
*p++ = MBEDTLS_ASN1_OID;
*p++ = (unsigned char) oid_size;
memcpy( p, oid, oid_size );
p += oid_size;
*p++ = MBEDTLS_ASN1_NULL;
*p++ = 0x00;
*p++ = MBEDTLS_ASN1_OCTET_STRING;
*p++ = (unsigned char) hashlen;
memcpy( p, hash, hashlen );
p += hashlen;
/* Just a sanity-check, should be automatic
* after the initial bounds check. */
if( p != dst + dst_len )
{
mbedtls_zeroize( dst, dst_len );
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
}
return( 0 );
}
/*
* Do an RSA operation to sign the message digest
*/
int mbedtls_rsa_rsassa_pkcs1_v15_sign( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig )
{
int ret;
unsigned char *sig_try = NULL, *verif = NULL;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
* Prepare PKCS1-v1.5 encoding (padding and hash identifier)
*/
if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash,
ctx->len, sig ) ) != 0 )
return( ret );
/*
* Call respective RSA primitive
*/
if( mode == MBEDTLS_RSA_PUBLIC )
{
/* Skip verification on a public key operation */
return( mbedtls_rsa_public( ctx, sig, sig ) );
}
/* Private key operation
*
* 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 ) );
if( mbedtls_safer_memcmp( verif, sig, ctx->len ) != 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 );
}
#endif /* MBEDTLS_PKCS1_V15 */
/*
* Do an RSA operation to sign the message digest
*/
int mbedtls_rsa_pkcs1_sign( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
unsigned char *sig )
{
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
case MBEDTLS_RSA_PKCS_V15:
return mbedtls_rsa_rsassa_pkcs1_v15_sign( ctx, f_rng, p_rng, mode, md_alg,
hashlen, hash, sig );
#endif
#if defined(MBEDTLS_PKCS1_V21)
case MBEDTLS_RSA_PKCS_V21:
return mbedtls_rsa_rsassa_pss_sign( ctx, f_rng, p_rng, mode, md_alg,
hashlen, hash, sig );
#endif
default:
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
}
}
#if defined(MBEDTLS_PKCS1_V21)
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function
*/
int mbedtls_rsa_rsassa_pss_verify_ext( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
mbedtls_md_type_t mgf1_hash_id,
int expected_salt_len,
const unsigned char *sig )
{
int ret;
size_t siglen;
unsigned char *p;
unsigned char *hash_start;
unsigned char result[MBEDTLS_MD_MAX_SIZE];
unsigned char zeros[8];
unsigned int hlen;
size_t observed_salt_len, msb;
const mbedtls_md_info_t *md_info;
mbedtls_md_context_t md_ctx;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V21 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
siglen = ctx->len;
if( siglen < 16 || siglen > sizeof( buf ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
ret = ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, sig, buf )
: mbedtls_rsa_private( ctx, f_rng, p_rng, sig, buf );
if( ret != 0 )
return( ret );
p = buf;
if( buf[siglen - 1] != 0xBC )
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
if( md_alg != MBEDTLS_MD_NONE )
{
/* Gather length of hash to sign */
md_info = mbedtls_md_info_from_type( md_alg );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hashlen = mbedtls_md_get_size( md_info );
}
md_info = mbedtls_md_info_from_type( mgf1_hash_id );
if( md_info == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hlen = mbedtls_md_get_size( md_info );
memset( zeros, 0, 8 );
/*
* Note: EMSA-PSS verification is over the length of N - 1 bits
*/
msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
if( buf[0] >> ( 8 - siglen * 8 + msb ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/* Compensate for boundary condition when applying mask */
if( msb % 8 == 0 )
{
p++;
siglen -= 1;
}
if( siglen < hlen + 2 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
hash_start = p + siglen - hlen - 1;
mbedtls_md_init( &md_ctx );
if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 0 ) ) != 0 )
goto exit;
ret = mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx );
if( ret != 0 )
goto exit;
buf[0] &= 0xFF >> ( siglen * 8 - msb );
while( p < hash_start - 1 && *p == 0 )
p++;
if( *p++ != 0x01 )
{
ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
goto exit;
}
observed_salt_len = hash_start - p;
if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY &&
observed_salt_len != (size_t) expected_salt_len )
{
ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
goto exit;
}
/*
* Generate H = Hash( M' )
*/
ret = mbedtls_md_starts( &md_ctx );
if ( ret != 0 )
goto exit;
ret = mbedtls_md_update( &md_ctx, zeros, 8 );
if ( ret != 0 )
goto exit;
ret = mbedtls_md_update( &md_ctx, hash, hashlen );
if ( ret != 0 )
goto exit;
ret = mbedtls_md_update( &md_ctx, p, observed_salt_len );
if ( ret != 0 )
goto exit;
ret = mbedtls_md_finish( &md_ctx, result );
if ( ret != 0 )
goto exit;
if( memcmp( hash_start, result, hlen ) != 0 )
{
ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
goto exit;
}
exit:
mbedtls_md_free( &md_ctx );
return( ret );
}
/*
* Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function
*/
int mbedtls_rsa_rsassa_pss_verify( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
const unsigned char *sig )
{
mbedtls_md_type_t mgf1_hash_id = ( ctx->hash_id != MBEDTLS_MD_NONE )
? (mbedtls_md_type_t) ctx->hash_id
: md_alg;
return( mbedtls_rsa_rsassa_pss_verify_ext( ctx, f_rng, p_rng, mode,
md_alg, hashlen, hash,
mgf1_hash_id, MBEDTLS_RSA_SALT_LEN_ANY,
sig ) );
}
#endif /* MBEDTLS_PKCS1_V21 */
#if defined(MBEDTLS_PKCS1_V15)
/*
* Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function
*/
int mbedtls_rsa_rsassa_pkcs1_v15_verify( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
const unsigned char *sig )
{
int ret = 0;
const size_t sig_len = ctx->len;
unsigned char *encoded = NULL, *encoded_expected = NULL;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
/*
* Prepare expected PKCS1 v1.5 encoding of hash.
*/
if( ( encoded = mbedtls_calloc( 1, sig_len ) ) == NULL ||
( encoded_expected = mbedtls_calloc( 1, sig_len ) ) == NULL )
{
ret = MBEDTLS_ERR_MPI_ALLOC_FAILED;
goto cleanup;
}
if( ( ret = rsa_rsassa_pkcs1_v15_encode( md_alg, hashlen, hash, sig_len,
encoded_expected ) ) != 0 )
goto cleanup;
/*
* Apply RSA primitive to get what should be PKCS1 encoded hash.
*/
ret = ( mode == MBEDTLS_RSA_PUBLIC )
? mbedtls_rsa_public( ctx, sig, encoded )
: mbedtls_rsa_private( ctx, f_rng, p_rng, sig, encoded );
if( ret != 0 )
goto cleanup;
/*
* Compare
*/
if( ( ret = mbedtls_safer_memcmp( encoded, encoded_expected,
sig_len ) ) != 0 )
{
ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
goto cleanup;
}
cleanup:
if( encoded != NULL )
{
mbedtls_zeroize( encoded, sig_len );
mbedtls_free( encoded );
}
if( encoded_expected != NULL )
{
mbedtls_zeroize( encoded_expected, sig_len );
mbedtls_free( encoded_expected );
}
return( ret );
}
#endif /* MBEDTLS_PKCS1_V15 */
/*
* Do an RSA operation and check the message digest
*/
int mbedtls_rsa_pkcs1_verify( mbedtls_rsa_context *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng,
int mode,
mbedtls_md_type_t md_alg,
unsigned int hashlen,
const unsigned char *hash,
const unsigned char *sig )
{
switch( ctx->padding )
{
#if defined(MBEDTLS_PKCS1_V15)
case MBEDTLS_RSA_PKCS_V15:
return mbedtls_rsa_rsassa_pkcs1_v15_verify( ctx, f_rng, p_rng, mode, md_alg,
hashlen, hash, sig );
#endif
#if defined(MBEDTLS_PKCS1_V21)
case MBEDTLS_RSA_PKCS_V21:
return mbedtls_rsa_rsassa_pss_verify( ctx, f_rng, p_rng, mode, md_alg,
hashlen, hash, sig );
#endif
default:
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
}
}
/*
* Copy the components of an RSA key
*/
int mbedtls_rsa_copy( mbedtls_rsa_context *dst, const mbedtls_rsa_context *src )
{
int ret;
dst->ver = src->ver;
dst->len = src->len;
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->N, &src->N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->E, &src->E ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->D, &src->D ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->P, &src->P ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Q, &src->Q ) );
#if !defined(MBEDTLS_RSA_NO_CRT)
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DP, &src->DP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->DQ, &src->DQ ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->QP, &src->QP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) );
#endif
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RN, &src->RN ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vi, &src->Vi ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->Vf, &src->Vf ) );
dst->padding = src->padding;
dst->hash_id = src->hash_id;
cleanup:
if( ret != 0 )
mbedtls_rsa_free( dst );
return( ret );
}
/*
* Free the components of an RSA key
*/
void mbedtls_rsa_free( mbedtls_rsa_context *ctx )
{
mbedtls_mpi_free( &ctx->Vi ); mbedtls_mpi_free( &ctx->Vf );
mbedtls_mpi_free( &ctx->RN ); mbedtls_mpi_free( &ctx->D );
mbedtls_mpi_free( &ctx->Q ); mbedtls_mpi_free( &ctx->P );
mbedtls_mpi_free( &ctx->E ); mbedtls_mpi_free( &ctx->N );
#if !defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi_free( &ctx->RQ ); mbedtls_mpi_free( &ctx->RP );
mbedtls_mpi_free( &ctx->QP ); mbedtls_mpi_free( &ctx->DQ );
mbedtls_mpi_free( &ctx->DP );
#endif /* MBEDTLS_RSA_NO_CRT */
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free( &ctx->mutex );
#endif
}
#endif /* !MBEDTLS_RSA_ALT */
#if defined(MBEDTLS_SELF_TEST)
#include "mbedtls/sha1.h"
/*
* Example RSA-1024 keypair, for test purposes
*/
#define KEY_LEN 128
#define RSA_N "9292758453063D803DD603D5E777D788" \
"8ED1D5BF35786190FA2F23EBC0848AEA" \
"DDA92CA6C3D80B32C4D109BE0F36D6AE" \
"7130B9CED7ACDF54CFC7555AC14EEBAB" \
"93A89813FBF3C4F8066D2D800F7C38A8" \
"1AE31942917403FF4946B0A83D3D3E05" \
"EE57C6F5F5606FB5D4BC6CD34EE0801A" \
"5E94BB77B07507233A0BC7BAC8F90F79"
#define RSA_E "10001"
#define RSA_D "24BF6185468786FDD303083D25E64EFC" \
"66CA472BC44D253102F8B4A9D3BFA750" \
"91386C0077937FE33FA3252D28855837" \
"AE1B484A8A9A45F7EE8C0C634F99E8CD" \
"DF79C5CE07EE72C7F123142198164234" \
"CABB724CF78B8173B9F880FC86322407" \
"AF1FEDFDDE2BEB674CA15F3E81A1521E" \
"071513A1E85B5DFA031F21ECAE91A34D"
#define RSA_P "C36D0EB7FCD285223CFB5AABA5BDA3D8" \
"2C01CAD19EA484A87EA4377637E75500" \
"FCB2005C5C7DD6EC4AC023CDA285D796" \
"C3D9E75E1EFC42488BB4F1D13AC30A57"
#define RSA_Q "C000DF51A7C77AE8D7C7370C1FF55B69" \
"E211C2B9E5DB1ED0BF61D0D9899620F4" \
"910E4168387E3C30AA1E00C339A79508" \
"8452DD96A9A5EA5D9DCA68DA636032AF"
#define PT_LEN 24
#define RSA_PT "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \
"\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD"
#if defined(MBEDTLS_PKCS1_V15)
static int myrand( void *rng_state, unsigned char *output, size_t len )
{
#if !defined(__OpenBSD__)
size_t i;
if( rng_state != NULL )
rng_state = NULL;
for( i = 0; i < len; ++i )
output[i] = rand();
#else
if( rng_state != NULL )
rng_state = NULL;
arc4random_buf( output, len );
#endif /* !OpenBSD */
return( 0 );
}
#endif /* MBEDTLS_PKCS1_V15 */
/*
* Checkup routine
*/
int mbedtls_rsa_self_test( int verbose )
{
int ret = 0;
#if defined(MBEDTLS_PKCS1_V15)
size_t len;
mbedtls_rsa_context rsa;
unsigned char rsa_plaintext[PT_LEN];
unsigned char rsa_decrypted[PT_LEN];
unsigned char rsa_ciphertext[KEY_LEN];
#if defined(MBEDTLS_SHA1_C)
unsigned char sha1sum[20];
#endif
mbedtls_mpi K;
mbedtls_mpi_init( &K );
mbedtls_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_N ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, &K, NULL, NULL, NULL, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_P ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, &K, NULL, NULL, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_Q ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, &K, NULL, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_D ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, &K, NULL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &K, 16, RSA_E ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_import( &rsa, NULL, NULL, NULL, NULL, &K ) );
MBEDTLS_MPI_CHK( mbedtls_rsa_complete( &rsa ) );
if( verbose != 0 )
mbedtls_printf( " RSA key validation: " );
if( mbedtls_rsa_check_pubkey( &rsa ) != 0 ||
mbedtls_rsa_check_privkey( &rsa ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto cleanup;
}
if( verbose != 0 )
mbedtls_printf( "passed\n PKCS#1 encryption : " );
memcpy( rsa_plaintext, RSA_PT, PT_LEN );
if( mbedtls_rsa_pkcs1_encrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PUBLIC,
PT_LEN, rsa_plaintext,
rsa_ciphertext ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto cleanup;
}
if( verbose != 0 )
mbedtls_printf( "passed\n PKCS#1 decryption : " );
if( mbedtls_rsa_pkcs1_decrypt( &rsa, myrand, NULL, MBEDTLS_RSA_PRIVATE,
&len, rsa_ciphertext, rsa_decrypted,
sizeof(rsa_decrypted) ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto cleanup;
}
if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto cleanup;
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
#if defined(MBEDTLS_SHA1_C)
if( verbose != 0 )
mbedtls_printf( " PKCS#1 data sign : " );
if( mbedtls_sha1_ret( rsa_plaintext, PT_LEN, sha1sum ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
return( 1 );
}
if( mbedtls_rsa_pkcs1_sign( &rsa, myrand, NULL,
MBEDTLS_RSA_PRIVATE, MBEDTLS_MD_SHA1, 0,
sha1sum, rsa_ciphertext ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto cleanup;
}
if( verbose != 0 )
mbedtls_printf( "passed\n PKCS#1 sig. verify: " );
if( mbedtls_rsa_pkcs1_verify( &rsa, NULL, NULL,
MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA1, 0,
sha1sum, rsa_ciphertext ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
ret = 1;
goto cleanup;
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
#endif /* MBEDTLS_SHA1_C */
if( verbose != 0 )
mbedtls_printf( "\n" );
cleanup:
mbedtls_mpi_free( &K );
mbedtls_rsa_free( &rsa );
#else /* MBEDTLS_PKCS1_V15 */
((void) verbose);
#endif /* MBEDTLS_PKCS1_V15 */
return( ret );
}
#endif /* MBEDTLS_SELF_TEST */
#endif /* MBEDTLS_RSA_C */