0,0 → 1,993 |
/* |
* Elliptic curve DSA |
* |
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved |
* SPDX-License-Identifier: GPL-2.0 |
* |
* This program is free software; you can redistribute it and/or modify |
* it under the terms of the GNU General Public License as published by |
* the Free Software Foundation; either version 2 of the License, or |
* (at your option) any later version. |
* |
* This program is distributed in the hope that it will be useful, |
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
* GNU General Public License for more details. |
* |
* You should have received a copy of the GNU General Public License along |
* with this program; if not, write to the Free Software Foundation, Inc., |
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
* |
* 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 == NULL ? NULL : &rs_ctx->ecp ) |
|
/* Utility macro for checking and updating ops budget */ |
#define ECDSA_BUDGET( ops ) \ |
MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, ECDSA_RS_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, |
int (*f_rng_blind)(void *, unsigned char *, size_t), |
void *p_rng_blind, |
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_blind, |
p_rng_blind, |
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_blind, |
p_rng_blind ) ); |
|
/* |
* 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_mod_mpi( pk, pk, &grp->N ) ); |
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 ); |
|
/* Use the same RNG for both blinding and ephemeral key generation */ |
return( ecdsa_sign_restartable( grp, r, s, d, buf, blen, |
f_rng, p_rng, 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, |
int (*f_rng_blind)(void *, unsigned char *, size_t), |
void *p_rng_blind, |
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 |
if( f_rng_blind != NULL ) |
ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen, |
mbedtls_hmac_drbg_random, p_rng, |
f_rng_blind, p_rng_blind, rs_ctx ); |
else |
{ |
mbedtls_hmac_drbg_context *p_rng_blind_det; |
|
#if !defined(MBEDTLS_ECP_RESTARTABLE) |
/* |
* To avoid reusing rng_ctx and risking incorrect behavior we seed a |
* second HMAC-DRBG with the same seed. We also apply a label to avoid |
* reusing the bits of the ephemeral key for blinding and eliminate the |
* risk that they leak this way. |
*/ |
const char* blind_label = "BLINDING CONTEXT"; |
mbedtls_hmac_drbg_context rng_ctx_blind; |
|
mbedtls_hmac_drbg_init( &rng_ctx_blind ); |
p_rng_blind_det = &rng_ctx_blind; |
|
mbedtls_hmac_drbg_seed_buf( p_rng_blind_det, md_info, |
data, 2 * grp_len ); |
ret = mbedtls_hmac_drbg_update_ret( p_rng_blind_det, |
(const unsigned char*) blind_label, |
strlen( blind_label ) ); |
if( ret != 0 ) |
{ |
mbedtls_hmac_drbg_free( &rng_ctx_blind ); |
goto cleanup; |
} |
#else |
/* |
* In the case of restartable computations we would either need to store |
* the second RNG in the restart context too or set it up at every |
* restart. The first option would penalize the correct application of |
* the function and the second would defeat the purpose of the |
* restartable feature. |
* |
* Therefore in this case we reuse the original RNG. This comes with the |
* price that the resulting signature might not be a valid deterministic |
* ECDSA signature with a very low probability (same magnitude as |
* successfully guessing the private key). However even then it is still |
* a valid ECDSA signature. |
*/ |
p_rng_blind_det = p_rng; |
#endif /* MBEDTLS_ECP_RESTARTABLE */ |
|
/* |
* Since the output of the RNGs is always the same for the same key and |
* message, this limits the efficiency of blinding and leaks information |
* through side channels. After mbedtls_ecdsa_sign_det() is removed NULL |
* won't be a valid value for f_rng_blind anymore. Therefore it should |
* be checked by the caller and this branch and check can be removed. |
*/ |
ret = ecdsa_sign_restartable( grp, r, s, d, buf, blen, |
mbedtls_hmac_drbg_random, p_rng, |
mbedtls_hmac_drbg_random, p_rng_blind_det, |
rs_ctx ); |
|
#if !defined(MBEDTLS_ECP_RESTARTABLE) |
mbedtls_hmac_drbg_free( &rng_ctx_blind ); |
#endif |
} |
#endif /* MBEDTLS_ECDSA_SIGN_ALT */ |
|
cleanup: |
mbedtls_hmac_drbg_free( &rng_ctx ); |
mbedtls_mpi_free( &h ); |
|
ECDSA_RS_LEAVE( det ); |
|
return( ret ); |
} |
|
/* |
* Deterministic signature wrappers |
*/ |
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, NULL, NULL ) ); |
} |
|
int mbedtls_ecdsa_sign_det_ext( 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, |
int (*f_rng_blind)(void *, unsigned char *, |
size_t), |
void *p_rng_blind ) |
{ |
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 ); |
ECDSA_VALIDATE_RET( f_rng_blind != NULL ); |
|
return( ecdsa_sign_det_restartable( grp, r, s, d, buf, blen, md_alg, |
f_rng_blind, p_rng_blind, 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) |
MBEDTLS_MPI_CHK( ecdsa_sign_det_restartable( &ctx->grp, &r, &s, &ctx->d, |
hash, hlen, md_alg, f_rng, |
p_rng, 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 |
/* Use the same RNG for both blinding and ephemeral key generation */ |
MBEDTLS_MPI_CHK( ecdsa_sign_restartable( &ctx->grp, &r, &s, &ctx->d, |
hash, hlen, f_rng, p_rng, 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 */ |