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31a2d14b92
mbedtls/library/rsa.c
Gilles Peskine 31a2d14b92 RSA PSS: fix first byte check for keys of size 8N+1 
For a key of size 8N+1, check that the first byte after applying the
public key operation is 0 (it could have been 1 instead). The code was
incorrectly doing a no-op check instead, which led to invalid
signatures being accepted. Not a security flaw, since you would need the
private key to craft such an invalid signature, but a bug nonetheless.
2017-10-19 15:43:53 +02:00

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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)
*/
/*
* RSA was designed by Ron Rivest, Adi Shamir and Len Adleman.
*
* http://theory.lcs.mit.edu/~rivest/rsapaper.pdf
* http://www.cacr.math.uwaterloo.ca/hac/about/chap8.pdf
* [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/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
/* 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;
}
/*
* 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;
}
#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 P1, Q1, 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( &P1 ); mbedtls_mpi_init( &Q1 );
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 );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) );
}
while( mbedtls_mpi_cmp_int( &G, 1 ) != 0 );
/*
* 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 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->DP, &ctx->D, &P1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->DQ, &ctx->D, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->QP, &ctx->Q, &ctx->P ) );
ctx->len = ( mbedtls_mpi_bitlen( &ctx->N ) + 7 ) >> 3;
cleanup:
mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 ); 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( !ctx->N.p || !ctx->E.p )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
if( ( ctx->N.p[0] & 1 ) == 0 ||
( ctx->E.p[0] & 1 ) == 0 )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
if( mbedtls_mpi_bitlen( &ctx->N ) < 128 ||
mbedtls_mpi_bitlen( &ctx->N ) > MBEDTLS_MPI_MAX_BITS )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
if( 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 a private RSA key
*/
int mbedtls_rsa_check_privkey( const mbedtls_rsa_context *ctx )
{
int ret;
mbedtls_mpi PQ, DE, P1, Q1, H, I, G, G2, L1, L2, DP, DQ, QP;
if( ( ret = mbedtls_rsa_check_pubkey( ctx ) ) != 0 )
return( ret );
if( !ctx->P.p || !ctx->Q.p || !ctx->D.p )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED );
mbedtls_mpi_init( &PQ ); mbedtls_mpi_init( &DE ); mbedtls_mpi_init( &P1 ); mbedtls_mpi_init( &Q1 );
mbedtls_mpi_init( &H ); mbedtls_mpi_init( &I ); mbedtls_mpi_init( &G ); mbedtls_mpi_init( &G2 );
mbedtls_mpi_init( &L1 ); mbedtls_mpi_init( &L2 ); mbedtls_mpi_init( &DP ); mbedtls_mpi_init( &DQ );
mbedtls_mpi_init( &QP );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &PQ, &ctx->P, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &DE, &ctx->D, &ctx->E ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &P1, &ctx->P, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &Q1, &ctx->Q, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &H, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G, &ctx->E, &H ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_gcd( &G2, &P1, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_div_mpi( &L1, &L2, &H, &G2 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &I, &DE, &L1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &DP, &ctx->D, &P1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &DQ, &ctx->D, &Q1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &QP, &ctx->Q, &ctx->P ) );
/*
* Check for a valid PKCS1v2 private key
*/
if( mbedtls_mpi_cmp_mpi( &PQ, &ctx->N ) != 0 ||
mbedtls_mpi_cmp_mpi( &DP, &ctx->DP ) != 0 ||
mbedtls_mpi_cmp_mpi( &DQ, &ctx->DQ ) != 0 ||
mbedtls_mpi_cmp_mpi( &QP, &ctx->QP ) != 0 ||
mbedtls_mpi_cmp_int( &L2, 0 ) != 0 ||
mbedtls_mpi_cmp_int( &I, 1 ) != 0 ||
mbedtls_mpi_cmp_int( &G, 1 ) != 0 )
{
ret = MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
}
cleanup:
mbedtls_mpi_free( &PQ ); mbedtls_mpi_free( &DE ); mbedtls_mpi_free( &P1 ); mbedtls_mpi_free( &Q1 );
mbedtls_mpi_free( &H ); mbedtls_mpi_free( &I ); mbedtls_mpi_free( &G ); mbedtls_mpi_free( &G2 );
mbedtls_mpi_free( &L1 ); mbedtls_mpi_free( &L2 ); mbedtls_mpi_free( &DP ); mbedtls_mpi_free( &DQ );
mbedtls_mpi_free( &QP );
if( ret == MBEDTLS_ERR_RSA_KEY_CHECK_FAILED )
return( ret );
if( ret != 0 )
return( MBEDTLS_ERR_RSA_KEY_CHECK_FAILED + ret );
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;
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;
mbedtls_mpi T, T1, T2;
mbedtls_mpi P1, Q1, R;
#if defined(MBEDTLS_RSA_NO_CRT)
mbedtls_mpi D_blind;
mbedtls_mpi *D = &ctx->D;
#else
mbedtls_mpi DP_blind, DQ_blind;
mbedtls_mpi *DP = &ctx->DP;
mbedtls_mpi *DQ = &ctx->DQ;
#endif
/* Make sure we have private key info, prevent possible misuse */
if( ctx->P.p == NULL || ctx->Q.p == NULL || ctx->D.p == NULL )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
mbedtls_mpi_init( &T ); mbedtls_mpi_init( &T1 ); mbedtls_mpi_init( &T2 );
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_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;
}
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
*
* T1 = input ^ dP mod P
* T2 = input ^ dQ mod Q
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T1, &T, DP, &ctx->P, &ctx->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &T2, &T, DQ, &ctx->Q, &ctx->RQ ) );
/*
* T = (T1 - T2) * (Q^-1 mod P) mod P
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( &T, &T1, &T2 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T1, &T, &ctx->QP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &T, &T1, &ctx->P ) );
/*
* T = T2 + T * Q
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &T1, &T, &ctx->Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &T, &T2, &T1 ) );
#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 ) );
}
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( &T ); mbedtls_mpi_free( &T1 ); mbedtls_mpi_free( &T2 );
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
}
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 void 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;
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;
mbedtls_md_starts( md_ctx );
mbedtls_md_update( md_ctx, src, slen );
mbedtls_md_update( md_ctx, counter, 4 );
mbedtls_md_finish( md_ctx, mask );
for( i = 0; i < use_len; ++i )
*p++ ^= mask[i];
counter[3]++;
dlen -= use_len;
}
mbedtls_zeroize( mask, sizeof( mask ) );
}
#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
//
mbedtls_md( md_info, label, label_len, p );
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 )
{
mbedtls_md_free( &md_ctx );
return( ret );
}
// maskedDB: Apply dbMask to DB
//
mgf_mask( output + hlen + 1, olen - hlen - 1, output + 1, hlen,
&md_ctx );
// maskedSeed: Apply seedMask to seed
//
mgf_mask( output + 1, hlen, output + hlen + 1, olen - hlen - 1,
&md_ctx );
mbedtls_md_free( &md_ctx );
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;
}
/* Generate lHash */
mbedtls_md( md_info, label, label_len, lhash );
/* seed: Apply seedMask to maskedSeed */
mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
&md_ctx );
/* DB: Apply dbMask to maskedDB */
mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
&md_ctx );
mbedtls_md_free( &md_ctx );
/*
* 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)
/*
* 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, pad_count = 0, i;
unsigned char *p, bad, pad_done = 0;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
ilen = ctx->len;
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;
p = buf;
bad = 0;
/*
* Check and get padding len in "constant-time"
*/
bad |= *p++; /* First byte must be 0 */
/* This test does not depend on secret data */
if( mode == MBEDTLS_RSA_PRIVATE )
{
bad |= *p++ ^ MBEDTLS_RSA_CRYPT;
/* Get padding len, but always read till end of buffer
* (minus one, for the 00 byte) */
for( i = 0; i < ilen - 3; i++ )
{
pad_done |= ((p[i] | (unsigned char)-p[i]) >> 7) ^ 1;
pad_count += ((pad_done | (unsigned char)-pad_done) >> 7) ^ 1;
}
p += pad_count;
bad |= *p++; /* Must be zero */
}
else
{
bad |= *p++ ^ MBEDTLS_RSA_SIGN;
/* Get padding len, but always read till end of buffer
* (minus one, for the 00 byte) */
for( i = 0; i < ilen - 3; i++ )
{
pad_done |= ( p[i] != 0xFF );
pad_count += ( pad_done == 0 );
}
p += pad_count;
bad |= *p++; /* Must be zero */
}
bad |= ( pad_count < 8 );
if( bad )
{
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 ) );
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 )
{
mbedtls_md_free( &md_ctx );
/* No need to zeroize salt: we didn't use it. */
return( ret );
}
// Generate H = Hash( M' )
//
mbedtls_md_starts( &md_ctx );
mbedtls_md_update( &md_ctx, p, 8 );
mbedtls_md_update( &md_ctx, hash, hashlen );
mbedtls_md_update( &md_ctx, salt, slen );
mbedtls_md_finish( &md_ctx, p );
mbedtls_zeroize( salt, sizeof( salt ) );
// Compensate for boundary condition when applying mask
//
if( msb % 8 == 0 )
offset = 1;
// maskedDB: Apply dbMask to DB
//
mgf_mask( sig + offset, olen - hlen - 1 - offset, p, hlen, &md_ctx );
mbedtls_md_free( &md_ctx );
msb = mbedtls_mpi_bitlen( &ctx->N ) - 1;
sig[0] &= 0xFF >> ( olen * 8 - msb );
p += hlen;
*p++ = 0xBC;
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
*/
/*
* 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 )
{
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 );
olen = ctx->len;
nb_pad = olen - 3;
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 );
nb_pad -= 10 + oid_size;
hashlen = mbedtls_md_get_size( md_info );
}
nb_pad -= hashlen;
if( ( nb_pad < 8 ) || ( nb_pad > olen ) )
return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
*p++ = 0;
*p++ = MBEDTLS_RSA_SIGN;
memset( p, 0xFF, nb_pad );
p += nb_pad;
*p++ = 0;
if( md_alg == MBEDTLS_MD_NONE )
{
memcpy( p, hash, hashlen );
}
else
{
/*
* DigestInfo ::= SEQUENCE {
* digestAlgorithm DigestAlgorithmIdentifier,
* digest Digest }
*
* DigestAlgorithmIdentifier ::= AlgorithmIdentifier
*
* Digest ::= OCTET STRING
*/
*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++ = oid_size & 0xFF;
memcpy( p, oid, oid_size );
p += oid_size;
*p++ = MBEDTLS_ASN1_NULL;
*p++ = 0x00;
*p++ = MBEDTLS_ASN1_OCTET_STRING;
*p++ = hashlen;
memcpy( p, hash, hashlen );
}
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 );
}
#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 buf[MBEDTLS_MPI_MAX_SIZE];
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;
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 )
{
mbedtls_md_free( &md_ctx );
return( ret );
}
mgf_mask( p, siglen - hlen - 1, hash_start, hlen, &md_ctx );
buf[0] &= 0xFF >> ( siglen * 8 - msb );
while( p < hash_start - 1 && *p == 0 )
p++;
if( p == hash_start ||
*p++ != 0x01 )
{
mbedtls_md_free( &md_ctx );
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
}
observed_salt_len = hash_start - p;
if( expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY &&
observed_salt_len != (size_t) expected_salt_len )
{
mbedtls_md_free( &md_ctx );
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
}
// Generate H = Hash( M' )
//
mbedtls_md_starts( &md_ctx );
mbedtls_md_update( &md_ctx, zeros, 8 );
mbedtls_md_update( &md_ctx, hash, hashlen );
mbedtls_md_update( &md_ctx, p, observed_salt_len );
mbedtls_md_finish( &md_ctx, result );
mbedtls_md_free( &md_ctx );
if( memcmp( hash_start, result, hlen ) == 0 )
return( 0 );
else
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
}
/*
* 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;
size_t len, siglen, asn1_len;
unsigned char *p, *p0, *end;
unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
mbedtls_md_type_t msg_md_alg;
const mbedtls_md_info_t *md_info;
mbedtls_asn1_buf oid;
if( mode == MBEDTLS_RSA_PRIVATE && ctx->padding != MBEDTLS_RSA_PKCS_V15 )
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( *p++ != 0 || *p++ != MBEDTLS_RSA_SIGN )
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
while( *p != 0 )
{
if( p >= buf + siglen - 1 || *p != 0xFF )
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
p++;
}
p++; /* skip 00 byte */
/* We've read: 00 01 PS 00 where PS must be at least 8 bytes */
if( p - buf < 11 )
return( MBEDTLS_ERR_RSA_INVALID_PADDING );
len = siglen - ( p - buf );
if( len == hashlen && md_alg == MBEDTLS_MD_NONE )
{
if( memcmp( p, hash, hashlen ) == 0 )
return( 0 );
else
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
}
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 );
end = p + len;
/*
* Parse the ASN.1 structure inside the PKCS#1 v1.5 structure.
* Insist on 2-byte length tags, to protect against variants of
* Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification.
*/
p0 = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &asn1_len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( p != p0 + 2 || asn1_len + 2 != len )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
p0 = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &asn1_len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( p != p0 + 2 || asn1_len + 6 + hashlen != len )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
p0 = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &oid.len, MBEDTLS_ASN1_OID ) ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( p != p0 + 2 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
oid.p = p;
p += oid.len;
if( mbedtls_oid_get_md_alg( &oid, &msg_md_alg ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( md_alg != msg_md_alg )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
/*
* assume the algorithm parameters must be NULL
*/
p0 = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &asn1_len, MBEDTLS_ASN1_NULL ) ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( p != p0 + 2 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
p0 = p;
if( ( ret = mbedtls_asn1_get_tag( &p, end, &asn1_len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( p != p0 + 2 || asn1_len != hashlen )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
if( memcmp( p, hash, hashlen ) != 0 )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
p += hashlen;
if( p != end )
return( MBEDTLS_ERR_RSA_VERIFY_FAILED );
return( 0 );
}
#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 ) );
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->RN, &src->RN ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RP, &src->RP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &dst->RQ, &src->RQ ) );
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->RQ ); mbedtls_mpi_free( &ctx->RP ); mbedtls_mpi_free( &ctx->RN );
mbedtls_mpi_free( &ctx->QP ); mbedtls_mpi_free( &ctx->DQ ); mbedtls_mpi_free( &ctx->DP );
mbedtls_mpi_free( &ctx->Q ); mbedtls_mpi_free( &ctx->P ); mbedtls_mpi_free( &ctx->D );
mbedtls_mpi_free( &ctx->E ); mbedtls_mpi_free( &ctx->N );
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free( &ctx->mutex );
#endif
}
#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 RSA_DP "C1ACF567564274FB07A0BBAD5D26E298" \
"3C94D22288ACD763FD8E5600ED4A702D" \
"F84198A5F06C2E72236AE490C93F07F8" \
"3CC559CD27BC2D1CA488811730BB5725"
#define RSA_DQ "4959CBF6F8FEF750AEE6977C155579C7" \
"D8AAEA56749EA28623272E4F7D0592AF" \
"7C1F1313CAC9471B5C523BFE592F517B" \
"407A1BD76C164B93DA2D32A383E58357"
#define RSA_QP "9AE7FBC99546432DF71896FC239EADAE" \
"F38D18D2B2F0E2DD275AA977E2BF4411" \
"F5A3B2A5D33605AEBBCCBA7FEB9F2D2F" \
"A74206CEC169D74BF5A8C50D6F48EA08"
#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_rsa_init( &rsa, MBEDTLS_RSA_PKCS_V15, 0 );
rsa.len = KEY_LEN;
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.N , 16, RSA_N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.E , 16, RSA_E ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.D , 16, RSA_D ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.P , 16, RSA_P ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.Q , 16, RSA_Q ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.DP, 16, RSA_DP ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.DQ, 16, RSA_DQ ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_string( &rsa.QP, 16, RSA_QP ) );
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" );
return( 1 );
}
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" );
return( 1 );
}
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" );
return( 1 );
}
if( memcmp( rsa_decrypted, rsa_plaintext, len ) != 0 )
{
if( verbose != 0 )
mbedtls_printf( "failed\n" );
return( 1 );
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
#if defined(MBEDTLS_SHA1_C)
if( verbose != 0 )
mbedtls_printf( "PKCS#1 data sign : " );
mbedtls_sha1( rsa_plaintext, PT_LEN, sha1sum );
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" );
return( 1 );
}
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" );
return( 1 );
}
if( verbose != 0 )
mbedtls_printf( "passed\n" );
#endif /* MBEDTLS_SHA1_C */
if( verbose != 0 )
mbedtls_printf( "\n" );
cleanup:
mbedtls_rsa_free( &rsa );
#else /* MBEDTLS_PKCS1_V15 */
((void) verbose);
#endif /* MBEDTLS_PKCS1_V15 */
return( ret );
}
#endif /* MBEDTLS_SELF_TEST */
#endif /* MBEDTLS_RSA_C */
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