/* | |
* Elliptic curve DSA | |
* | |
* 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) | |
*/ | |
/* | |
* References: | |
* | |
* SEC1 http://www.secg.org/index.php?action=secg,docs_secg | |
*/ | |
#if !defined(MBEDTLS_CONFIG_FILE) | |
#include "mbedtls/config.h" | |
#else | |
#include MBEDTLS_CONFIG_FILE | |
#endif | |
#if defined(MBEDTLS_ECDSA_C) | |
#include "mbedtls/ecdsa.h" | |
#include "mbedtls/asn1write.h" | |
#include <string.h> | |
#if defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
#include "mbedtls/hmac_drbg.h" | |
#endif | |
#if defined(MBEDTLS_PLATFORM_C) | |
#include "mbedtls/platform.h" | |
#else | |
#include <stdlib.h> | |
#define mbedtls_calloc calloc | |
#define mbedtls_free free | |
#endif | |
#include "mbedtls/platform_util.h" | |
/* Parameter validation macros based on platform_util.h */ | |
#define ECDSA_VALIDATE_RET( cond ) \ | |
MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_ECP_BAD_INPUT_DATA ) | |
#define ECDSA_VALIDATE( cond ) \ | |
MBEDTLS_INTERNAL_VALIDATE( cond ) | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
/* | |
* Sub-context for ecdsa_verify() | |
*/ | |
struct mbedtls_ecdsa_restart_ver | |
{ | |
mbedtls_mpi u1, u2; /* intermediate values */ | |
enum { /* what to do next? */ | |
ecdsa_ver_init = 0, /* getting started */ | |
ecdsa_ver_muladd, /* muladd step */ | |
} state; | |
}; | |
/* | |
* Init verify restart sub-context | |
*/ | |
static void ecdsa_restart_ver_init( mbedtls_ecdsa_restart_ver_ctx *ctx ) | |
{ | |
mbedtls_mpi_init( &ctx->u1 ); | |
mbedtls_mpi_init( &ctx->u2 ); | |
ctx->state = ecdsa_ver_init; | |
} | |
/* | |
* Free the components of a verify restart sub-context | |
*/ | |
static void ecdsa_restart_ver_free( mbedtls_ecdsa_restart_ver_ctx *ctx ) | |
{ | |
if( ctx == NULL ) | |
return; | |
mbedtls_mpi_free( &ctx->u1 ); | |
mbedtls_mpi_free( &ctx->u2 ); | |
ecdsa_restart_ver_init( ctx ); | |
} | |
/* | |
* Sub-context for ecdsa_sign() | |
*/ | |
struct mbedtls_ecdsa_restart_sig | |
{ | |
int sign_tries; | |
int key_tries; | |
mbedtls_mpi k; /* per-signature random */ | |
mbedtls_mpi r; /* r value */ | |
enum { /* what to do next? */ | |
ecdsa_sig_init = 0, /* getting started */ | |
ecdsa_sig_mul, /* doing ecp_mul() */ | |
ecdsa_sig_modn, /* mod N computations */ | |
} state; | |
}; | |
/* | |
* Init verify sign sub-context | |
*/ | |
static void ecdsa_restart_sig_init( mbedtls_ecdsa_restart_sig_ctx *ctx ) | |
{ | |
ctx->sign_tries = 0; | |
ctx->key_tries = 0; | |
mbedtls_mpi_init( &ctx->k ); | |
mbedtls_mpi_init( &ctx->r ); | |
ctx->state = ecdsa_sig_init; | |
} | |
/* | |
* Free the components of a sign restart sub-context | |
*/ | |
static void ecdsa_restart_sig_free( mbedtls_ecdsa_restart_sig_ctx *ctx ) | |
{ | |
if( ctx == NULL ) | |
return; | |
mbedtls_mpi_free( &ctx->k ); | |
mbedtls_mpi_free( &ctx->r ); | |
} | |
#if defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
/* | |
* Sub-context for ecdsa_sign_det() | |
*/ | |
struct mbedtls_ecdsa_restart_det | |
{ | |
mbedtls_hmac_drbg_context rng_ctx; /* DRBG state */ | |
enum { /* what to do next? */ | |
ecdsa_det_init = 0, /* getting started */ | |
ecdsa_det_sign, /* make signature */ | |
} state; | |
}; | |
/* | |
* Init verify sign_det sub-context | |
*/ | |
static void ecdsa_restart_det_init( mbedtls_ecdsa_restart_det_ctx *ctx ) | |
{ | |
mbedtls_hmac_drbg_init( &ctx->rng_ctx ); | |
ctx->state = ecdsa_det_init; | |
} | |
/* | |
* Free the components of a sign_det restart sub-context | |
*/ | |
static void ecdsa_restart_det_free( mbedtls_ecdsa_restart_det_ctx *ctx ) | |
{ | |
if( ctx == NULL ) | |
return; | |
mbedtls_hmac_drbg_free( &ctx->rng_ctx ); | |
ecdsa_restart_det_init( ctx ); | |
} | |
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */ | |
#define ECDSA_RS_ECP &rs_ctx->ecp | |
/* Utility macro for checking and updating ops budget */ | |
#define ECDSA_BUDGET( ops ) \ | |
MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, &rs_ctx->ecp, ops ) ); | |
/* Call this when entering a function that needs its own sub-context */ | |
#define ECDSA_RS_ENTER( SUB ) do { \ | |
/* reset ops count for this call if top-level */ \ | |
if( rs_ctx != NULL && rs_ctx->ecp.depth++ == 0 ) \ | |
rs_ctx->ecp.ops_done = 0; \ | |
\ | |
/* set up our own sub-context if needed */ \ | |
if( mbedtls_ecp_restart_is_enabled() && \ | |
rs_ctx != NULL && rs_ctx->SUB == NULL ) \ | |
{ \ | |
rs_ctx->SUB = mbedtls_calloc( 1, sizeof( *rs_ctx->SUB ) ); \ | |
if( rs_ctx->SUB == NULL ) \ | |
return( MBEDTLS_ERR_ECP_ALLOC_FAILED ); \ | |
\ | |
ecdsa_restart_## SUB ##_init( rs_ctx->SUB ); \ | |
} \ | |
} while( 0 ) | |
/* Call this when leaving a function that needs its own sub-context */ | |
#define ECDSA_RS_LEAVE( SUB ) do { \ | |
/* clear our sub-context when not in progress (done or error) */ \ | |
if( rs_ctx != NULL && rs_ctx->SUB != NULL && \ | |
ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) \ | |
{ \ | |
ecdsa_restart_## SUB ##_free( rs_ctx->SUB ); \ | |
mbedtls_free( rs_ctx->SUB ); \ | |
rs_ctx->SUB = NULL; \ | |
} \ | |
\ | |
if( rs_ctx != NULL ) \ | |
rs_ctx->ecp.depth--; \ | |
} while( 0 ) | |
#else /* MBEDTLS_ECP_RESTARTABLE */ | |
#define ECDSA_RS_ECP NULL | |
#define ECDSA_BUDGET( ops ) /* no-op; for compatibility */ | |
#define ECDSA_RS_ENTER( SUB ) (void) rs_ctx | |
#define ECDSA_RS_LEAVE( SUB ) (void) rs_ctx | |
#endif /* MBEDTLS_ECP_RESTARTABLE */ | |
/* | |
* Derive a suitable integer for group grp from a buffer of length len | |
* SEC1 4.1.3 step 5 aka SEC1 4.1.4 step 3 | |
*/ | |
static int derive_mpi( const mbedtls_ecp_group *grp, mbedtls_mpi *x, | |
const unsigned char *buf, size_t blen ) | |
{ | |
int ret; | |
size_t n_size = ( grp->nbits + 7 ) / 8; | |
size_t use_size = blen > n_size ? n_size : blen; | |
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( x, buf, use_size ) ); | |
if( use_size * 8 > grp->nbits ) | |
MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( x, use_size * 8 - grp->nbits ) ); | |
/* While at it, reduce modulo N */ | |
if( mbedtls_mpi_cmp_mpi( x, &grp->N ) >= 0 ) | |
MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mpi( x, x, &grp->N ) ); | |
cleanup: | |
return( ret ); | |
} | |
#if !defined(MBEDTLS_ECDSA_SIGN_ALT) | |
/* | |
* Compute ECDSA signature of a hashed message (SEC1 4.1.3) | |
* Obviously, compared to SEC1 4.1.3, we skip step 4 (hash message) | |
*/ | |
static int ecdsa_sign_restartable( mbedtls_ecp_group *grp, | |
mbedtls_mpi *r, mbedtls_mpi *s, | |
const mbedtls_mpi *d, const unsigned char *buf, size_t blen, | |
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, | |
mbedtls_ecdsa_restart_ctx *rs_ctx ) | |
{ | |
int ret, key_tries, sign_tries; | |
int *p_sign_tries = &sign_tries, *p_key_tries = &key_tries; | |
mbedtls_ecp_point R; | |
mbedtls_mpi k, e, t; | |
mbedtls_mpi *pk = &k, *pr = r; | |
/* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */ | |
if( grp->N.p == NULL ) | |
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); | |
/* Make sure d is in range 1..n-1 */ | |
if( mbedtls_mpi_cmp_int( d, 1 ) < 0 || mbedtls_mpi_cmp_mpi( d, &grp->N ) >= 0 ) | |
return( MBEDTLS_ERR_ECP_INVALID_KEY ); | |
mbedtls_ecp_point_init( &R ); | |
mbedtls_mpi_init( &k ); mbedtls_mpi_init( &e ); mbedtls_mpi_init( &t ); | |
ECDSA_RS_ENTER( sig ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->sig != NULL ) | |
{ | |
/* redirect to our context */ | |
p_sign_tries = &rs_ctx->sig->sign_tries; | |
p_key_tries = &rs_ctx->sig->key_tries; | |
pk = &rs_ctx->sig->k; | |
pr = &rs_ctx->sig->r; | |
/* jump to current step */ | |
if( rs_ctx->sig->state == ecdsa_sig_mul ) | |
goto mul; | |
if( rs_ctx->sig->state == ecdsa_sig_modn ) | |
goto modn; | |
} | |
#endif /* MBEDTLS_ECP_RESTARTABLE */ | |
*p_sign_tries = 0; | |
do | |
{ | |
if( *p_sign_tries++ > 10 ) | |
{ | |
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; | |
goto cleanup; | |
} | |
/* | |
* Steps 1-3: generate a suitable ephemeral keypair | |
* and set r = xR mod n | |
*/ | |
*p_key_tries = 0; | |
do | |
{ | |
if( *p_key_tries++ > 10 ) | |
{ | |
ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; | |
goto cleanup; | |
} | |
MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, pk, f_rng, p_rng ) ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->sig != NULL ) | |
rs_ctx->sig->state = ecdsa_sig_mul; | |
mul: | |
#endif | |
MBEDTLS_MPI_CHK( mbedtls_ecp_mul_restartable( grp, &R, pk, &grp->G, | |
f_rng, p_rng, ECDSA_RS_ECP ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pr, &R.X, &grp->N ) ); | |
} | |
while( mbedtls_mpi_cmp_int( pr, 0 ) == 0 ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->sig != NULL ) | |
rs_ctx->sig->state = ecdsa_sig_modn; | |
modn: | |
#endif | |
/* | |
* Accounting for everything up to the end of the loop | |
* (step 6, but checking now avoids saving e and t) | |
*/ | |
ECDSA_BUDGET( MBEDTLS_ECP_OPS_INV + 4 ); | |
/* | |
* Step 5: derive MPI from hashed message | |
*/ | |
MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) ); | |
/* | |
* Generate a random value to blind inv_mod in next step, | |
* avoiding a potential timing leak. | |
*/ | |
MBEDTLS_MPI_CHK( mbedtls_ecp_gen_privkey( grp, &t, f_rng, p_rng ) ); | |
/* | |
* Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n | |
*/ | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, pr, d ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &e, &e, s ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &e, &e, &t ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pk, pk, &t ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, pk, &grp->N ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) ); | |
} | |
while( mbedtls_mpi_cmp_int( s, 0 ) == 0 ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->sig != NULL ) | |
mbedtls_mpi_copy( r, pr ); | |
#endif | |
cleanup: | |
mbedtls_ecp_point_free( &R ); | |
mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t ); | |
ECDSA_RS_LEAVE( sig ); | |
return( ret ); | |
} | |
/* | |
* Compute ECDSA signature of a hashed message | |
*/ | |
int mbedtls_ecdsa_sign( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s, | |
const mbedtls_mpi *d, const unsigned char *buf, size_t blen, | |
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) | |
{ | |
ECDSA_VALIDATE_RET( grp != NULL ); | |
ECDSA_VALIDATE_RET( r != NULL ); | |
ECDSA_VALIDATE_RET( s != NULL ); | |
ECDSA_VALIDATE_RET( d != NULL ); | |
ECDSA_VALIDATE_RET( f_rng != NULL ); | |
ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); | |
return( ecdsa_sign_restartable( grp, r, s, d, buf, blen, | |
f_rng, p_rng, NULL ) ); | |
} | |
#endif /* !MBEDTLS_ECDSA_SIGN_ALT */ | |
#if defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
/* | |
* Deterministic signature wrapper | |
*/ | |
static int ecdsa_sign_det_restartable( mbedtls_ecp_group *grp, | |
mbedtls_mpi *r, mbedtls_mpi *s, | |
const mbedtls_mpi *d, const unsigned char *buf, size_t blen, | |
mbedtls_md_type_t md_alg, | |
mbedtls_ecdsa_restart_ctx *rs_ctx ) | |
{ | |
int ret; | |
mbedtls_hmac_drbg_context rng_ctx; | |
mbedtls_hmac_drbg_context *p_rng = &rng_ctx; | |
unsigned char data[2 * MBEDTLS_ECP_MAX_BYTES]; | |
size_t grp_len = ( grp->nbits + 7 ) / 8; | |
const mbedtls_md_info_t *md_info; | |
mbedtls_mpi h; | |
if( ( md_info = mbedtls_md_info_from_type( md_alg ) ) == NULL ) | |
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); | |
mbedtls_mpi_init( &h ); | |
mbedtls_hmac_drbg_init( &rng_ctx ); | |
ECDSA_RS_ENTER( det ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->det != NULL ) | |
{ | |
/* redirect to our context */ | |
p_rng = &rs_ctx->det->rng_ctx; | |
/* jump to current step */ | |
if( rs_ctx->det->state == ecdsa_det_sign ) | |
goto sign; | |
} | |
#endif /* MBEDTLS_ECP_RESTARTABLE */ | |
/* Use private key and message hash (reduced) to initialize HMAC_DRBG */ | |
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( d, data, grp_len ) ); | |
MBEDTLS_MPI_CHK( derive_mpi( grp, &h, buf, blen ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, data + grp_len, grp_len ) ); | |
mbedtls_hmac_drbg_seed_buf( p_rng, md_info, data, 2 * grp_len ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->det != NULL ) | |
rs_ctx->det->state = ecdsa_det_sign; | |
sign: | |
#endif | |
#if defined(MBEDTLS_ECDSA_SIGN_ALT) | |
ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen, | |
mbedtls_hmac_drbg_random, p_rng ); | |
#else | |
ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen, | |
mbedtls_hmac_drbg_random, p_rng, rs_ctx ); | |
#endif /* MBEDTLS_ECDSA_SIGN_ALT */ | |
cleanup: | |
mbedtls_hmac_drbg_free( &rng_ctx ); | |
mbedtls_mpi_free( &h ); | |
ECDSA_RS_LEAVE( det ); | |
return( ret ); | |
} | |
/* | |
* Deterministic signature wrapper | |
*/ | |
int mbedtls_ecdsa_sign_det( mbedtls_ecp_group *grp, mbedtls_mpi *r, mbedtls_mpi *s, | |
const mbedtls_mpi *d, const unsigned char *buf, size_t blen, | |
mbedtls_md_type_t md_alg ) | |
{ | |
ECDSA_VALIDATE_RET( grp != NULL ); | |
ECDSA_VALIDATE_RET( r != NULL ); | |
ECDSA_VALIDATE_RET( s != NULL ); | |
ECDSA_VALIDATE_RET( d != NULL ); | |
ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); | |
return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg, NULL ) ); | |
} | |
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */ | |
#if !defined(MBEDTLS_ECDSA_VERIFY_ALT) | |
/* | |
* Verify ECDSA signature of hashed message (SEC1 4.1.4) | |
* Obviously, compared to SEC1 4.1.3, we skip step 2 (hash message) | |
*/ | |
static int ecdsa_verify_restartable( mbedtls_ecp_group *grp, | |
const unsigned char *buf, size_t blen, | |
const mbedtls_ecp_point *Q, | |
const mbedtls_mpi *r, const mbedtls_mpi *s, | |
mbedtls_ecdsa_restart_ctx *rs_ctx ) | |
{ | |
int ret; | |
mbedtls_mpi e, s_inv, u1, u2; | |
mbedtls_ecp_point R; | |
mbedtls_mpi *pu1 = &u1, *pu2 = &u2; | |
mbedtls_ecp_point_init( &R ); | |
mbedtls_mpi_init( &e ); mbedtls_mpi_init( &s_inv ); | |
mbedtls_mpi_init( &u1 ); mbedtls_mpi_init( &u2 ); | |
/* Fail cleanly on curves such as Curve25519 that can't be used for ECDSA */ | |
if( grp->N.p == NULL ) | |
return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); | |
ECDSA_RS_ENTER( ver ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->ver != NULL ) | |
{ | |
/* redirect to our context */ | |
pu1 = &rs_ctx->ver->u1; | |
pu2 = &rs_ctx->ver->u2; | |
/* jump to current step */ | |
if( rs_ctx->ver->state == ecdsa_ver_muladd ) | |
goto muladd; | |
} | |
#endif /* MBEDTLS_ECP_RESTARTABLE */ | |
/* | |
* Step 1: make sure r and s are in range 1..n-1 | |
*/ | |
if( mbedtls_mpi_cmp_int( r, 1 ) < 0 || mbedtls_mpi_cmp_mpi( r, &grp->N ) >= 0 || | |
mbedtls_mpi_cmp_int( s, 1 ) < 0 || mbedtls_mpi_cmp_mpi( s, &grp->N ) >= 0 ) | |
{ | |
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; | |
goto cleanup; | |
} | |
/* | |
* Step 3: derive MPI from hashed message | |
*/ | |
MBEDTLS_MPI_CHK( derive_mpi( grp, &e, buf, blen ) ); | |
/* | |
* Step 4: u1 = e / s mod n, u2 = r / s mod n | |
*/ | |
ECDSA_BUDGET( MBEDTLS_ECP_OPS_CHK + MBEDTLS_ECP_OPS_INV + 2 ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu1, &e, &s_inv ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pu1, pu1, &grp->N ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( pu2, r, &s_inv ) ); | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( pu2, pu2, &grp->N ) ); | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
if( rs_ctx != NULL && rs_ctx->ver != NULL ) | |
rs_ctx->ver->state = ecdsa_ver_muladd; | |
muladd: | |
#endif | |
/* | |
* Step 5: R = u1 G + u2 Q | |
*/ | |
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd_restartable( grp, | |
&R, pu1, &grp->G, pu2, Q, ECDSA_RS_ECP ) ); | |
if( mbedtls_ecp_is_zero( &R ) ) | |
{ | |
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; | |
goto cleanup; | |
} | |
/* | |
* Step 6: convert xR to an integer (no-op) | |
* Step 7: reduce xR mod n (gives v) | |
*/ | |
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &R.X, &R.X, &grp->N ) ); | |
/* | |
* Step 8: check if v (that is, R.X) is equal to r | |
*/ | |
if( mbedtls_mpi_cmp_mpi( &R.X, r ) != 0 ) | |
{ | |
ret = MBEDTLS_ERR_ECP_VERIFY_FAILED; | |
goto cleanup; | |
} | |
cleanup: | |
mbedtls_ecp_point_free( &R ); | |
mbedtls_mpi_free( &e ); mbedtls_mpi_free( &s_inv ); | |
mbedtls_mpi_free( &u1 ); mbedtls_mpi_free( &u2 ); | |
ECDSA_RS_LEAVE( ver ); | |
return( ret ); | |
} | |
/* | |
* Verify ECDSA signature of hashed message | |
*/ | |
int mbedtls_ecdsa_verify( mbedtls_ecp_group *grp, | |
const unsigned char *buf, size_t blen, | |
const mbedtls_ecp_point *Q, | |
const mbedtls_mpi *r, | |
const mbedtls_mpi *s) | |
{ | |
ECDSA_VALIDATE_RET( grp != NULL ); | |
ECDSA_VALIDATE_RET( Q != NULL ); | |
ECDSA_VALIDATE_RET( r != NULL ); | |
ECDSA_VALIDATE_RET( s != NULL ); | |
ECDSA_VALIDATE_RET( buf != NULL || blen == 0 ); | |
return( ecdsa_verify_restartable( grp, buf, blen, Q, r, s, NULL ) ); | |
} | |
#endif /* !MBEDTLS_ECDSA_VERIFY_ALT */ | |
/* | |
* Convert a signature (given by context) to ASN.1 | |
*/ | |
static int ecdsa_signature_to_asn1( const mbedtls_mpi *r, const mbedtls_mpi *s, | |
unsigned char *sig, size_t *slen ) | |
{ | |
int ret; | |
unsigned char buf[MBEDTLS_ECDSA_MAX_LEN]; | |
unsigned char *p = buf + sizeof( buf ); | |
size_t len = 0; | |
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, s ) ); | |
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &p, buf, r ) ); | |
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) ); | |
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf, | |
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); | |
memcpy( sig, p, len ); | |
*slen = len; | |
return( 0 ); | |
} | |
/* | |
* Compute and write signature | |
*/ | |
int mbedtls_ecdsa_write_signature_restartable( mbedtls_ecdsa_context *ctx, | |
mbedtls_md_type_t md_alg, | |
const unsigned char *hash, size_t hlen, | |
unsigned char *sig, size_t *slen, | |
int (*f_rng)(void *, unsigned char *, size_t), | |
void *p_rng, | |
mbedtls_ecdsa_restart_ctx *rs_ctx ) | |
{ | |
int ret; | |
mbedtls_mpi r, s; | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( hash != NULL ); | |
ECDSA_VALIDATE_RET( sig != NULL ); | |
ECDSA_VALIDATE_RET( slen != NULL ); | |
mbedtls_mpi_init( &r ); | |
mbedtls_mpi_init( &s ); | |
#if defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
(void) f_rng; | |
(void) p_rng; | |
MBEDTLS_MPI_CHK( ecdsa_sign_det_restartable( &ctx->grp, &r, &s, &ctx->d, | |
hash, hlen, md_alg, rs_ctx ) ); | |
#else | |
(void) md_alg; | |
#if defined(MBEDTLS_ECDSA_SIGN_ALT) | |
MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d, | |
hash, hlen, f_rng, p_rng ) ); | |
#else | |
MBEDTLS_MPI_CHK( ecdsa_sign_restartable( &ctx->grp, &r, &s, &ctx->d, | |
hash, hlen, f_rng, p_rng, rs_ctx ) ); | |
#endif /* MBEDTLS_ECDSA_SIGN_ALT */ | |
#endif /* MBEDTLS_ECDSA_DETERMINISTIC */ | |
MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) ); | |
cleanup: | |
mbedtls_mpi_free( &r ); | |
mbedtls_mpi_free( &s ); | |
return( ret ); | |
} | |
/* | |
* Compute and write signature | |
*/ | |
int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, | |
mbedtls_md_type_t md_alg, | |
const unsigned char *hash, size_t hlen, | |
unsigned char *sig, size_t *slen, | |
int (*f_rng)(void *, unsigned char *, size_t), | |
void *p_rng ) | |
{ | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( hash != NULL ); | |
ECDSA_VALIDATE_RET( sig != NULL ); | |
ECDSA_VALIDATE_RET( slen != NULL ); | |
return( mbedtls_ecdsa_write_signature_restartable( | |
ctx, md_alg, hash, hlen, sig, slen, f_rng, p_rng, NULL ) ); | |
} | |
#if !defined(MBEDTLS_DEPRECATED_REMOVED) && \ | |
defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
int mbedtls_ecdsa_write_signature_det( mbedtls_ecdsa_context *ctx, | |
const unsigned char *hash, size_t hlen, | |
unsigned char *sig, size_t *slen, | |
mbedtls_md_type_t md_alg ) | |
{ | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( hash != NULL ); | |
ECDSA_VALIDATE_RET( sig != NULL ); | |
ECDSA_VALIDATE_RET( slen != NULL ); | |
return( mbedtls_ecdsa_write_signature( ctx, md_alg, hash, hlen, sig, slen, | |
NULL, NULL ) ); | |
} | |
#endif | |
/* | |
* Read and check signature | |
*/ | |
int mbedtls_ecdsa_read_signature( mbedtls_ecdsa_context *ctx, | |
const unsigned char *hash, size_t hlen, | |
const unsigned char *sig, size_t slen ) | |
{ | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( hash != NULL ); | |
ECDSA_VALIDATE_RET( sig != NULL ); | |
return( mbedtls_ecdsa_read_signature_restartable( | |
ctx, hash, hlen, sig, slen, NULL ) ); | |
} | |
/* | |
* Restartable read and check signature | |
*/ | |
int mbedtls_ecdsa_read_signature_restartable( mbedtls_ecdsa_context *ctx, | |
const unsigned char *hash, size_t hlen, | |
const unsigned char *sig, size_t slen, | |
mbedtls_ecdsa_restart_ctx *rs_ctx ) | |
{ | |
int ret; | |
unsigned char *p = (unsigned char *) sig; | |
const unsigned char *end = sig + slen; | |
size_t len; | |
mbedtls_mpi r, s; | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( hash != NULL ); | |
ECDSA_VALIDATE_RET( sig != NULL ); | |
mbedtls_mpi_init( &r ); | |
mbedtls_mpi_init( &s ); | |
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, | |
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) | |
{ | |
ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA; | |
goto cleanup; | |
} | |
if( p + len != end ) | |
{ | |
ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA + | |
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH; | |
goto cleanup; | |
} | |
if( ( ret = mbedtls_asn1_get_mpi( &p, end, &r ) ) != 0 || | |
( ret = mbedtls_asn1_get_mpi( &p, end, &s ) ) != 0 ) | |
{ | |
ret += MBEDTLS_ERR_ECP_BAD_INPUT_DATA; | |
goto cleanup; | |
} | |
#if defined(MBEDTLS_ECDSA_VERIFY_ALT) | |
if( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen, | |
&ctx->Q, &r, &s ) ) != 0 ) | |
goto cleanup; | |
#else | |
if( ( ret = ecdsa_verify_restartable( &ctx->grp, hash, hlen, | |
&ctx->Q, &r, &s, rs_ctx ) ) != 0 ) | |
goto cleanup; | |
#endif /* MBEDTLS_ECDSA_VERIFY_ALT */ | |
/* At this point we know that the buffer starts with a valid signature. | |
* Return 0 if the buffer just contains the signature, and a specific | |
* error code if the valid signature is followed by more data. */ | |
if( p != end ) | |
ret = MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH; | |
cleanup: | |
mbedtls_mpi_free( &r ); | |
mbedtls_mpi_free( &s ); | |
return( ret ); | |
} | |
#if !defined(MBEDTLS_ECDSA_GENKEY_ALT) | |
/* | |
* Generate key pair | |
*/ | |
int mbedtls_ecdsa_genkey( mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id gid, | |
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) | |
{ | |
int ret = 0; | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( f_rng != NULL ); | |
ret = mbedtls_ecp_group_load( &ctx->grp, gid ); | |
if( ret != 0 ) | |
return( ret ); | |
return( mbedtls_ecp_gen_keypair( &ctx->grp, &ctx->d, | |
&ctx->Q, f_rng, p_rng ) ); | |
} | |
#endif /* !MBEDTLS_ECDSA_GENKEY_ALT */ | |
/* | |
* Set context from an mbedtls_ecp_keypair | |
*/ | |
int mbedtls_ecdsa_from_keypair( mbedtls_ecdsa_context *ctx, const mbedtls_ecp_keypair *key ) | |
{ | |
int ret; | |
ECDSA_VALIDATE_RET( ctx != NULL ); | |
ECDSA_VALIDATE_RET( key != NULL ); | |
if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 || | |
( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 || | |
( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 ) | |
{ | |
mbedtls_ecdsa_free( ctx ); | |
} | |
return( ret ); | |
} | |
/* | |
* Initialize context | |
*/ | |
void mbedtls_ecdsa_init( mbedtls_ecdsa_context *ctx ) | |
{ | |
ECDSA_VALIDATE( ctx != NULL ); | |
mbedtls_ecp_keypair_init( ctx ); | |
} | |
/* | |
* Free context | |
*/ | |
void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx ) | |
{ | |
if( ctx == NULL ) | |
return; | |
mbedtls_ecp_keypair_free( ctx ); | |
} | |
#if defined(MBEDTLS_ECP_RESTARTABLE) | |
/* | |
* Initialize a restart context | |
*/ | |
void mbedtls_ecdsa_restart_init( mbedtls_ecdsa_restart_ctx *ctx ) | |
{ | |
ECDSA_VALIDATE( ctx != NULL ); | |
mbedtls_ecp_restart_init( &ctx->ecp ); | |
ctx->ver = NULL; | |
ctx->sig = NULL; | |
#if defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
ctx->det = NULL; | |
#endif | |
} | |
/* | |
* Free the components of a restart context | |
*/ | |
void mbedtls_ecdsa_restart_free( mbedtls_ecdsa_restart_ctx *ctx ) | |
{ | |
if( ctx == NULL ) | |
return; | |
mbedtls_ecp_restart_free( &ctx->ecp ); | |
ecdsa_restart_ver_free( ctx->ver ); | |
mbedtls_free( ctx->ver ); | |
ctx->ver = NULL; | |
ecdsa_restart_sig_free( ctx->sig ); | |
mbedtls_free( ctx->sig ); | |
ctx->sig = NULL; | |
#if defined(MBEDTLS_ECDSA_DETERMINISTIC) | |
ecdsa_restart_det_free( ctx->det ); | |
mbedtls_free( ctx->det ); | |
ctx->det = NULL; | |
#endif | |
} | |
#endif /* MBEDTLS_ECP_RESTARTABLE */ | |
#endif /* MBEDTLS_ECDSA_C */ |