diff options
Diffstat (limited to 'thirdparty/mbedtls/library/ecdsa.c')
| -rw-r--r-- | thirdparty/mbedtls/library/ecdsa.c | 458 |
1 files changed, 458 insertions, 0 deletions
diff --git a/thirdparty/mbedtls/library/ecdsa.c b/thirdparty/mbedtls/library/ecdsa.c new file mode 100644 index 0000000000..826fefe5c6 --- /dev/null +++ b/thirdparty/mbedtls/library/ecdsa.c @@ -0,0 +1,458 @@ +/* + * 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 + +/* + * 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) + */ +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 ) +{ + int ret, key_tries, sign_tries, blind_tries; + mbedtls_ecp_point R; + mbedtls_mpi k, e, t; + + /* 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 ); + + sign_tries = 0; + do + { + /* + * Steps 1-3: generate a suitable ephemeral keypair + * and set r = xR mod n + */ + key_tries = 0; + do + { + MBEDTLS_MPI_CHK( mbedtls_ecp_gen_keypair( grp, &k, &R, f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( r, &R.X, &grp->N ) ); + + if( key_tries++ > 10 ) + { + ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; + goto cleanup; + } + } + while( mbedtls_mpi_cmp_int( r, 0 ) == 0 ); + + /* + * 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. + */ + blind_tries = 0; + do + { + size_t n_size = ( grp->nbits + 7 ) / 8; + MBEDTLS_MPI_CHK( mbedtls_mpi_fill_random( &t, n_size, f_rng, p_rng ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &t, 8 * n_size - grp->nbits ) ); + + /* See mbedtls_ecp_gen_keypair() */ + if( ++blind_tries > 30 ) + return( MBEDTLS_ERR_ECP_RANDOM_FAILED ); + } + while( mbedtls_mpi_cmp_int( &t, 1 ) < 0 || + mbedtls_mpi_cmp_mpi( &t, &grp->N ) >= 0 ); + + /* + * Step 6: compute s = (e + r * d) / k = t (e + rd) / (kt) mod n + */ + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, r, 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( &k, &k, &t ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( s, &k, &grp->N ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( s, s, &e ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( s, s, &grp->N ) ); + + if( sign_tries++ > 10 ) + { + ret = MBEDTLS_ERR_ECP_RANDOM_FAILED; + goto cleanup; + } + } + while( mbedtls_mpi_cmp_int( s, 0 ) == 0 ); + +cleanup: + mbedtls_ecp_point_free( &R ); + mbedtls_mpi_free( &k ); mbedtls_mpi_free( &e ); mbedtls_mpi_free( &t ); + + return( ret ); +} +#endif /* MBEDTLS_ECDSA_SIGN_ALT */ + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) +/* + * 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 ) +{ + int ret; + mbedtls_hmac_drbg_context 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 ); + + /* 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( &rng_ctx, md_info, data, 2 * grp_len ); + + ret = mbedtls_ecdsa_sign( grp, r, s, d, buf, blen, + mbedtls_hmac_drbg_random, &rng_ctx ); + +cleanup: + mbedtls_hmac_drbg_free( &rng_ctx ); + mbedtls_mpi_free( &h ); + + return( ret ); +} +#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) + */ +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) +{ + int ret; + mbedtls_mpi e, s_inv, u1, u2; + mbedtls_ecp_point R; + + 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 ); + + /* + * 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; + } + + /* + * Additional precaution: make sure Q is valid + */ + MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) ); + + /* + * 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 + */ + MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &s_inv, s, &grp->N ) ); + + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u1, &e, &s_inv ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u1, &u1, &grp->N ) ); + + MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &u2, r, &s_inv ) ); + MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &u2, &u2, &grp->N ) ); + + /* + * Step 5: R = u1 G + u2 Q + * + * Since we're not using any secret data, no need to pass a RNG to + * mbedtls_ecp_mul() for countermesures. + */ + MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, &R, &u1, &grp->G, &u2, Q ) ); + + 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 ); + + return( ret ); +} +#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( 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 ) +{ + int ret; + mbedtls_mpi r, s; + + mbedtls_mpi_init( &r ); + mbedtls_mpi_init( &s ); + +#if defined(MBEDTLS_ECDSA_DETERMINISTIC) + (void) f_rng; + (void) p_rng; + + MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign_det( &ctx->grp, &r, &s, &ctx->d, + hash, hlen, md_alg ) ); +#else + (void) md_alg; + + MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d, + hash, hlen, f_rng, p_rng ) ); +#endif + + MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) ); + +cleanup: + mbedtls_mpi_free( &r ); + mbedtls_mpi_free( &s ); + + return( ret ); +} + +#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 ) +{ + 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 ) +{ + int ret; + unsigned char *p = (unsigned char *) sig; + const unsigned char *end = sig + slen; + size_t len; + mbedtls_mpi r, s; + + 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( ( ret = mbedtls_ecdsa_verify( &ctx->grp, hash, hlen, + &ctx->Q, &r, &s ) ) != 0 ) + goto cleanup; + + 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 ) +{ + return( mbedtls_ecp_group_load( &ctx->grp, gid ) || + 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; + + 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 ) +{ + mbedtls_ecp_keypair_init( ctx ); +} + +/* + * Free context + */ +void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx ) +{ + mbedtls_ecp_keypair_free( ctx ); +} + +#endif /* MBEDTLS_ECDSA_C */ |