mbed TLS upgraded to 2.6.0
Fork of mbedtls by
library/ecdh.c
- Committer:
- Jasper Wallace
- Date:
- 2017-09-29
- Revision:
- 2:bbdeda018a3c
- Parent:
- 0:cdf462088d13
File content as of revision 2:bbdeda018a3c:
/* * Elliptic curve Diffie-Hellman * * 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 * RFC 4492 */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_ECDH_C) #include "mbedtls/ecdh.h" #include <string.h> /* * Generate public key: simple wrapper around mbedtls_ecp_gen_keypair */ int mbedtls_ecdh_gen_public( mbedtls_ecp_group *grp, mbedtls_mpi *d, mbedtls_ecp_point *Q, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { return mbedtls_ecp_gen_keypair( grp, d, Q, f_rng, p_rng ); } /* * Compute shared secret (SEC1 3.3.1) */ int mbedtls_ecdh_compute_shared( mbedtls_ecp_group *grp, mbedtls_mpi *z, const mbedtls_ecp_point *Q, const mbedtls_mpi *d, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; mbedtls_ecp_point P; mbedtls_ecp_point_init( &P ); /* * Make sure Q is a valid pubkey before using it */ MBEDTLS_MPI_CHK( mbedtls_ecp_check_pubkey( grp, Q ) ); MBEDTLS_MPI_CHK( mbedtls_ecp_mul( grp, &P, d, Q, f_rng, p_rng ) ); if( mbedtls_ecp_is_zero( &P ) ) { ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA; goto cleanup; } MBEDTLS_MPI_CHK( mbedtls_mpi_copy( z, &P.X ) ); cleanup: mbedtls_ecp_point_free( &P ); return( ret ); } /* * Initialize context */ void mbedtls_ecdh_init( mbedtls_ecdh_context *ctx ) { memset( ctx, 0, sizeof( mbedtls_ecdh_context ) ); } /* * Free context */ void mbedtls_ecdh_free( mbedtls_ecdh_context *ctx ) { if( ctx == NULL ) return; mbedtls_ecp_group_free( &ctx->grp ); mbedtls_ecp_point_free( &ctx->Q ); mbedtls_ecp_point_free( &ctx->Qp ); mbedtls_ecp_point_free( &ctx->Vi ); mbedtls_ecp_point_free( &ctx->Vf ); mbedtls_mpi_free( &ctx->d ); mbedtls_mpi_free( &ctx->z ); mbedtls_mpi_free( &ctx->_d ); } /* * Setup and write the ServerKeyExhange parameters (RFC 4492) * struct { * ECParameters curve_params; * ECPoint public; * } ServerECDHParams; */ int mbedtls_ecdh_make_params( mbedtls_ecdh_context *ctx, size_t *olen, unsigned char *buf, size_t blen, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; size_t grp_len, pt_len; if( ctx == NULL || ctx->grp.pbits == 0 ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) ) != 0 ) return( ret ); if( ( ret = mbedtls_ecp_tls_write_group( &ctx->grp, &grp_len, buf, blen ) ) != 0 ) return( ret ); buf += grp_len; blen -= grp_len; if( ( ret = mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format, &pt_len, buf, blen ) ) != 0 ) return( ret ); *olen = grp_len + pt_len; return( 0 ); } /* * Read the ServerKeyExhange parameters (RFC 4492) * struct { * ECParameters curve_params; * ECPoint public; * } ServerECDHParams; */ int mbedtls_ecdh_read_params( mbedtls_ecdh_context *ctx, const unsigned char **buf, const unsigned char *end ) { int ret; if( ( ret = mbedtls_ecp_tls_read_group( &ctx->grp, buf, end - *buf ) ) != 0 ) return( ret ); if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, buf, end - *buf ) ) != 0 ) return( ret ); return( 0 ); } /* * Get parameters from a keypair */ int mbedtls_ecdh_get_params( mbedtls_ecdh_context *ctx, const mbedtls_ecp_keypair *key, mbedtls_ecdh_side side ) { int ret; if( ( ret = mbedtls_ecp_group_copy( &ctx->grp, &key->grp ) ) != 0 ) return( ret ); /* If it's not our key, just import the public part as Qp */ if( side == MBEDTLS_ECDH_THEIRS ) return( mbedtls_ecp_copy( &ctx->Qp, &key->Q ) ); /* Our key: import public (as Q) and private parts */ if( side != MBEDTLS_ECDH_OURS ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); if( ( ret = mbedtls_ecp_copy( &ctx->Q, &key->Q ) ) != 0 || ( ret = mbedtls_mpi_copy( &ctx->d, &key->d ) ) != 0 ) return( ret ); return( 0 ); } /* * Setup and export the client public value */ int mbedtls_ecdh_make_public( mbedtls_ecdh_context *ctx, size_t *olen, unsigned char *buf, size_t blen, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; if( ctx == NULL || ctx->grp.pbits == 0 ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); if( ( ret = mbedtls_ecdh_gen_public( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) ) != 0 ) return( ret ); return mbedtls_ecp_tls_write_point( &ctx->grp, &ctx->Q, ctx->point_format, olen, buf, blen ); } /* * Parse and import the client's public value */ int mbedtls_ecdh_read_public( mbedtls_ecdh_context *ctx, const unsigned char *buf, size_t blen ) { int ret; const unsigned char *p = buf; if( ctx == NULL ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); if( ( ret = mbedtls_ecp_tls_read_point( &ctx->grp, &ctx->Qp, &p, blen ) ) != 0 ) return( ret ); if( (size_t)( p - buf ) != blen ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); return( 0 ); } /* * Derive and export the shared secret */ int mbedtls_ecdh_calc_secret( mbedtls_ecdh_context *ctx, size_t *olen, unsigned char *buf, size_t blen, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; if( ctx == NULL ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); if( ( ret = mbedtls_ecdh_compute_shared( &ctx->grp, &ctx->z, &ctx->Qp, &ctx->d, f_rng, p_rng ) ) != 0 ) { return( ret ); } if( mbedtls_mpi_size( &ctx->z ) > blen ) return( MBEDTLS_ERR_ECP_BAD_INPUT_DATA ); *olen = ctx->grp.pbits / 8 + ( ( ctx->grp.pbits % 8 ) != 0 ); return mbedtls_mpi_write_binary( &ctx->z, buf, *olen ); } #endif /* MBEDTLS_ECDH_C */