| /* |
| * Elliptic curve DSA |
| * |
| * Copyright The Mbed TLS Contributors |
| * 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. |
| */ |
| |
| /* |
| * References: |
| * |
| * SEC1 http://www.secg.org/index.php?action=secg,docs_secg |
| */ |
| |
| #include "common.h" |
| |
| #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" |
| #include "mbedtls/error.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 */ |
| |
| #if defined(MBEDTLS_ECDSA_DETERMINISTIC) || \ |
| !defined(MBEDTLS_ECDSA_SIGN_ALT) || \ |
| !defined(MBEDTLS_ECDSA_VERIFY_ALT) |
| /* |
| * 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| 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 ); |
| } |
| #endif /* ECDSA_DETERMINISTIC || !ECDSA_SIGN_ALT || !ECDSA_VERIFY_ALT */ |
| |
| #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( ! mbedtls_ecdsa_can_do( grp->id ) || 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 ); |
| } |
| |
| int mbedtls_ecdsa_can_do( mbedtls_ecp_group_id gid ) |
| { |
| switch( gid ) |
| { |
| #ifdef MBEDTLS_ECP_DP_CURVE25519_ENABLED |
| case MBEDTLS_ECP_DP_CURVE25519: return 0; |
| #endif |
| #ifdef MBEDTLS_ECP_DP_CURVE448_ENABLED |
| case MBEDTLS_ECP_DP_CURVE448: return 0; |
| #endif |
| default: return 1; |
| } |
| } |
| |
| /* |
| * 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 |
| * |
| * note: The f_rng_blind parameter must not be NULL. |
| * |
| */ |
| 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_ERR_ERROR_CORRUPTION_DETECTED; |
| 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) |
| (void) f_rng_blind; |
| (void) p_rng_blind; |
| 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, |
| f_rng_blind, p_rng_blind, 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_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_ERR_ERROR_CORRUPTION_DETECTED; |
| 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( ! mbedtls_ecdsa_can_do( grp->id ) || 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 sig_size, |
| size_t *slen ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| unsigned char buf[MBEDTLS_ECDSA_MAX_LEN] = {0}; |
| 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 ) ); |
| |
| if( len > sig_size ) |
| return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL ); |
| |
| 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 sig_size, size_t *slen, |
| int (*f_rng)(void *, unsigned char *, size_t), |
| void *p_rng, |
| mbedtls_ecdsa_restart_ctx *rs_ctx ) |
| { |
| int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| mbedtls_mpi r, s; |
| ECDSA_VALIDATE_RET( ctx != NULL ); |
| ECDSA_VALIDATE_RET( hash != NULL ); |
| ECDSA_VALIDATE_RET( sig != NULL ); |
| ECDSA_VALIDATE_RET( slen != NULL ); |
| |
| if( f_rng == NULL ) |
| return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); |
| |
| 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) |
| (void) rs_ctx; |
| |
| 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, sig_size, 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 sig_size, 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, sig_size, slen, |
| f_rng, p_rng, NULL ) ); |
| } |
| |
| /* |
| * 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| 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_ERROR_ADD( 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) |
| (void) rs_ctx; |
| |
| 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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; |
| 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 */ |
