/* * Public Key layer for writing key files and structures * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later * * This file is provided under the Apache License 2.0, or the * GNU General Public License v2.0 or later. * * ********** * Apache License 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. * * ********** * * ********** * GNU General Public License v2.0 or later: * * 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) */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_PK_WRITE_C) #include "mbedtls/pk.h" #include "mbedtls/asn1write.h" #include "mbedtls/oid.h" #include "mbedtls/platform_util.h" #include <string.h> #if defined(MBEDTLS_RSA_C) #include "mbedtls/rsa.h" #endif #if defined(MBEDTLS_ECP_C) #include "mbedtls/bignum.h" #include "mbedtls/ecp.h" #include "mbedtls/platform_util.h" #endif #if defined(MBEDTLS_ECDSA_C) #include "mbedtls/ecdsa.h" #endif #if defined(MBEDTLS_PEM_WRITE_C) #include "mbedtls/pem.h" #endif #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include <stdlib.h> #define mbedtls_calloc calloc #define mbedtls_free free #endif /* Parameter validation macros based on platform_util.h */ #define PK_VALIDATE_RET( cond ) \ MBEDTLS_INTERNAL_VALIDATE_RET( cond, MBEDTLS_ERR_PK_BAD_INPUT_DATA ) #define PK_VALIDATE( cond ) \ MBEDTLS_INTERNAL_VALIDATE( cond ) #if defined(MBEDTLS_RSA_C) /* * RSAPublicKey ::= SEQUENCE { * modulus INTEGER, -- n * publicExponent INTEGER -- e * } */ static int pk_write_rsa_pubkey( unsigned char **p, unsigned char *start, mbedtls_rsa_context *rsa ) { int ret; size_t len = 0; mbedtls_mpi T; mbedtls_mpi_init( &T ); /* Export E */ if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, NULL, NULL, &T ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( p, start, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export N */ if ( ( ret = mbedtls_rsa_export( rsa, &T, NULL, NULL, NULL, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( p, start, &T ) ) < 0 ) goto end_of_export; len += ret; end_of_export: mbedtls_mpi_free( &T ); if( ret < 0 ) return( ret ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); return( (int) len ); } #endif /* MBEDTLS_RSA_C */ #if defined(MBEDTLS_ECP_C) /* * EC public key is an EC point */ static int pk_write_ec_pubkey( unsigned char **p, unsigned char *start, mbedtls_ecp_keypair *ec ) { int ret; size_t len = 0; unsigned char buf[MBEDTLS_ECP_MAX_PT_LEN]; if( ( ret = mbedtls_ecp_point_write_binary( &ec->grp, &ec->Q, MBEDTLS_ECP_PF_UNCOMPRESSED, &len, buf, sizeof( buf ) ) ) != 0 ) { return( ret ); } if( *p < start || (size_t)( *p - start ) < len ) return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); *p -= len; memcpy( *p, buf, len ); return( (int) len ); } /* * ECParameters ::= CHOICE { * namedCurve OBJECT IDENTIFIER * } */ static int pk_write_ec_param( unsigned char **p, unsigned char *start, mbedtls_ecp_keypair *ec ) { int ret; size_t len = 0; const char *oid; size_t oid_len; if( ( ret = mbedtls_oid_get_oid_by_ec_grp( ec->grp.id, &oid, &oid_len ) ) != 0 ) return( ret ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) ); return( (int) len ); } /* * privateKey OCTET STRING -- always of length ceil(log2(n)/8) */ static int pk_write_ec_private( unsigned char **p, unsigned char *start, mbedtls_ecp_keypair *ec ) { int ret; size_t byte_length = ( ec->grp.pbits + 7 ) / 8; unsigned char tmp[MBEDTLS_ECP_MAX_BYTES]; ret = mbedtls_mpi_write_binary( &ec->d, tmp, byte_length ); if( ret != 0 ) goto exit; ret = mbedtls_asn1_write_octet_string( p, start, tmp, byte_length ); exit: mbedtls_platform_zeroize( tmp, byte_length ); return( ret ); } #endif /* MBEDTLS_ECP_C */ int mbedtls_pk_write_pubkey( unsigned char **p, unsigned char *start, const mbedtls_pk_context *key ) { int ret; size_t len = 0; PK_VALIDATE_RET( p != NULL ); PK_VALIDATE_RET( *p != NULL ); PK_VALIDATE_RET( start != NULL ); PK_VALIDATE_RET( key != NULL ); #if defined(MBEDTLS_RSA_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA ) MBEDTLS_ASN1_CHK_ADD( len, pk_write_rsa_pubkey( p, start, mbedtls_pk_rsa( *key ) ) ); else #endif #if defined(MBEDTLS_ECP_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) MBEDTLS_ASN1_CHK_ADD( len, pk_write_ec_pubkey( p, start, mbedtls_pk_ec( *key ) ) ); else #endif return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE ); return( (int) len ); } int mbedtls_pk_write_pubkey_der( mbedtls_pk_context *key, unsigned char *buf, size_t size ) { int ret; unsigned char *c; size_t len = 0, par_len = 0, oid_len; const char *oid; PK_VALIDATE_RET( key != NULL ); if( size == 0 ) return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); PK_VALIDATE_RET( buf != NULL ); c = buf + size; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, key ) ); if( c - buf < 1 ) return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); /* * SubjectPublicKeyInfo ::= SEQUENCE { * algorithm AlgorithmIdentifier, * subjectPublicKey BIT STRING } */ *--c = 0; len += 1; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_BIT_STRING ) ); if( ( ret = mbedtls_oid_get_oid_by_pk_alg( mbedtls_pk_get_type( key ), &oid, &oid_len ) ) != 0 ) { return( ret ); } #if defined(MBEDTLS_ECP_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) { MBEDTLS_ASN1_CHK_ADD( par_len, pk_write_ec_param( &c, buf, mbedtls_pk_ec( *key ) ) ); } #endif MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_algorithm_identifier( &c, buf, oid, oid_len, par_len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); return( (int) len ); } int mbedtls_pk_write_key_der( mbedtls_pk_context *key, unsigned char *buf, size_t size ) { int ret; unsigned char *c; size_t len = 0; PK_VALIDATE_RET( key != NULL ); if( size == 0 ) return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); PK_VALIDATE_RET( buf != NULL ); c = buf + size; #if defined(MBEDTLS_RSA_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA ) { mbedtls_mpi T; /* Temporary holding the exported parameters */ mbedtls_rsa_context *rsa = mbedtls_pk_rsa( *key ); /* * Export the parameters one after another to avoid simultaneous copies. */ mbedtls_mpi_init( &T ); /* Export QP */ if( ( ret = mbedtls_rsa_export_crt( rsa, NULL, NULL, &T ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export DQ */ if( ( ret = mbedtls_rsa_export_crt( rsa, NULL, &T, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export DP */ if( ( ret = mbedtls_rsa_export_crt( rsa, &T, NULL, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export Q */ if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, &T, NULL, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export P */ if ( ( ret = mbedtls_rsa_export( rsa, NULL, &T, NULL, NULL, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export D */ if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, NULL, &T, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export E */ if ( ( ret = mbedtls_rsa_export( rsa, NULL, NULL, NULL, NULL, &T ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; /* Export N */ if ( ( ret = mbedtls_rsa_export( rsa, &T, NULL, NULL, NULL, NULL ) ) != 0 || ( ret = mbedtls_asn1_write_mpi( &c, buf, &T ) ) < 0 ) goto end_of_export; len += ret; end_of_export: mbedtls_mpi_free( &T ); if( ret < 0 ) return( ret ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 0 ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); } else #endif /* MBEDTLS_RSA_C */ #if defined(MBEDTLS_ECP_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) { mbedtls_ecp_keypair *ec = mbedtls_pk_ec( *key ); size_t pub_len = 0, par_len = 0; /* * RFC 5915, or SEC1 Appendix C.4 * * ECPrivateKey ::= SEQUENCE { * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), * privateKey OCTET STRING, * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, * publicKey [1] BIT STRING OPTIONAL * } */ /* publicKey */ MBEDTLS_ASN1_CHK_ADD( pub_len, pk_write_ec_pubkey( &c, buf, ec ) ); if( c - buf < 1 ) return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); *--c = 0; pub_len += 1; MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_len( &c, buf, pub_len ) ); MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_BIT_STRING ) ); MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_len( &c, buf, pub_len ) ); MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 1 ) ); len += pub_len; /* parameters */ MBEDTLS_ASN1_CHK_ADD( par_len, pk_write_ec_param( &c, buf, ec ) ); MBEDTLS_ASN1_CHK_ADD( par_len, mbedtls_asn1_write_len( &c, buf, par_len ) ); MBEDTLS_ASN1_CHK_ADD( par_len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 0 ) ); len += par_len; /* privateKey */ MBEDTLS_ASN1_CHK_ADD( len, pk_write_ec_private( &c, buf, ec ) ); /* version */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 1 ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); } else #endif /* MBEDTLS_ECP_C */ return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE ); return( (int) len ); } #if defined(MBEDTLS_PEM_WRITE_C) #define PEM_BEGIN_PUBLIC_KEY "-----BEGIN PUBLIC KEY-----\n" #define PEM_END_PUBLIC_KEY "-----END PUBLIC KEY-----\n" #define PEM_BEGIN_PRIVATE_KEY_RSA "-----BEGIN RSA PRIVATE KEY-----\n" #define PEM_END_PRIVATE_KEY_RSA "-----END RSA PRIVATE KEY-----\n" #define PEM_BEGIN_PRIVATE_KEY_EC "-----BEGIN EC PRIVATE KEY-----\n" #define PEM_END_PRIVATE_KEY_EC "-----END EC PRIVATE KEY-----\n" /* * Max sizes of key per types. Shown as tag + len (+ content). */ #if defined(MBEDTLS_RSA_C) /* * RSA public keys: * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 3 * algorithm AlgorithmIdentifier, 1 + 1 (sequence) * + 1 + 1 + 9 (rsa oid) * + 1 + 1 (params null) * subjectPublicKey BIT STRING } 1 + 3 + (1 + below) * RSAPublicKey ::= SEQUENCE { 1 + 3 * modulus INTEGER, -- n 1 + 3 + MPI_MAX + 1 * publicExponent INTEGER -- e 1 + 3 + MPI_MAX + 1 * } */ #define RSA_PUB_DER_MAX_BYTES 38 + 2 * MBEDTLS_MPI_MAX_SIZE /* * RSA private keys: * RSAPrivateKey ::= SEQUENCE { 1 + 3 * version Version, 1 + 1 + 1 * modulus INTEGER, 1 + 3 + MPI_MAX + 1 * publicExponent INTEGER, 1 + 3 + MPI_MAX + 1 * privateExponent INTEGER, 1 + 3 + MPI_MAX + 1 * prime1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 * prime2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 * exponent1 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 * exponent2 INTEGER, 1 + 3 + MPI_MAX / 2 + 1 * coefficient INTEGER, 1 + 3 + MPI_MAX / 2 + 1 * otherPrimeInfos OtherPrimeInfos OPTIONAL 0 (not supported) * } */ #define MPI_MAX_SIZE_2 MBEDTLS_MPI_MAX_SIZE / 2 + \ MBEDTLS_MPI_MAX_SIZE % 2 #define RSA_PRV_DER_MAX_BYTES 47 + 3 * MBEDTLS_MPI_MAX_SIZE \ + 5 * MPI_MAX_SIZE_2 #else /* MBEDTLS_RSA_C */ #define RSA_PUB_DER_MAX_BYTES 0 #define RSA_PRV_DER_MAX_BYTES 0 #endif /* MBEDTLS_RSA_C */ #if defined(MBEDTLS_ECP_C) /* * EC public keys: * SubjectPublicKeyInfo ::= SEQUENCE { 1 + 2 * algorithm AlgorithmIdentifier, 1 + 1 (sequence) * + 1 + 1 + 7 (ec oid) * + 1 + 1 + 9 (namedCurve oid) * subjectPublicKey BIT STRING 1 + 2 + 1 [1] * + 1 (point format) [1] * + 2 * ECP_MAX (coords) [1] * } */ #define ECP_PUB_DER_MAX_BYTES 30 + 2 * MBEDTLS_ECP_MAX_BYTES /* * EC private keys: * ECPrivateKey ::= SEQUENCE { 1 + 2 * version INTEGER , 1 + 1 + 1 * privateKey OCTET STRING, 1 + 1 + ECP_MAX * parameters [0] ECParameters OPTIONAL, 1 + 1 + (1 + 1 + 9) * publicKey [1] BIT STRING OPTIONAL 1 + 2 + [1] above * } */ #define ECP_PRV_DER_MAX_BYTES 29 + 3 * MBEDTLS_ECP_MAX_BYTES #else /* MBEDTLS_ECP_C */ #define ECP_PUB_DER_MAX_BYTES 0 #define ECP_PRV_DER_MAX_BYTES 0 #endif /* MBEDTLS_ECP_C */ #define PUB_DER_MAX_BYTES RSA_PUB_DER_MAX_BYTES > ECP_PUB_DER_MAX_BYTES ? \ RSA_PUB_DER_MAX_BYTES : ECP_PUB_DER_MAX_BYTES #define PRV_DER_MAX_BYTES RSA_PRV_DER_MAX_BYTES > ECP_PRV_DER_MAX_BYTES ? \ RSA_PRV_DER_MAX_BYTES : ECP_PRV_DER_MAX_BYTES int mbedtls_pk_write_pubkey_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size ) { int ret; unsigned char output_buf[PUB_DER_MAX_BYTES]; size_t olen = 0; PK_VALIDATE_RET( key != NULL ); PK_VALIDATE_RET( buf != NULL || size == 0 ); if( ( ret = mbedtls_pk_write_pubkey_der( key, output_buf, sizeof(output_buf) ) ) < 0 ) { return( ret ); } if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_PUBLIC_KEY, PEM_END_PUBLIC_KEY, output_buf + sizeof(output_buf) - ret, ret, buf, size, &olen ) ) != 0 ) { return( ret ); } return( 0 ); } int mbedtls_pk_write_key_pem( mbedtls_pk_context *key, unsigned char *buf, size_t size ) { int ret; unsigned char output_buf[PRV_DER_MAX_BYTES]; const char *begin, *end; size_t olen = 0; PK_VALIDATE_RET( key != NULL ); PK_VALIDATE_RET( buf != NULL || size == 0 ); if( ( ret = mbedtls_pk_write_key_der( key, output_buf, sizeof(output_buf) ) ) < 0 ) return( ret ); #if defined(MBEDTLS_RSA_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_RSA ) { begin = PEM_BEGIN_PRIVATE_KEY_RSA; end = PEM_END_PRIVATE_KEY_RSA; } else #endif #if defined(MBEDTLS_ECP_C) if( mbedtls_pk_get_type( key ) == MBEDTLS_PK_ECKEY ) { begin = PEM_BEGIN_PRIVATE_KEY_EC; end = PEM_END_PRIVATE_KEY_EC; } else #endif return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE ); if( ( ret = mbedtls_pem_write_buffer( begin, end, output_buf + sizeof(output_buf) - ret, ret, buf, size, &olen ) ) != 0 ) { return( ret ); } return( 0 ); } #endif /* MBEDTLS_PEM_WRITE_C */ #endif /* MBEDTLS_PK_WRITE_C */