/* * X.509 certificate writing * * Copyright The Mbed TLS Contributors * 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. * * ********** */ /* * References: * - certificates: RFC 5280, updated by RFC 6818 * - CSRs: PKCS#10 v1.7 aka RFC 2986 * - attributes: PKCS#9 v2.0 aka RFC 2985 */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_X509_CRT_WRITE_C) #include "mbedtls/x509_crt.h" #include "mbedtls/oid.h" #include "mbedtls/asn1write.h" #include "mbedtls/sha1.h" #include "mbedtls/platform_util.h" #include #if defined(MBEDTLS_PEM_WRITE_C) #include "mbedtls/pem.h" #endif /* MBEDTLS_PEM_WRITE_C */ /* * For the currently used signature algorithms the buffer to store any signature * must be at least of size MAX(MBEDTLS_ECDSA_MAX_LEN, MBEDTLS_MPI_MAX_SIZE) */ #if MBEDTLS_ECDSA_MAX_LEN > MBEDTLS_MPI_MAX_SIZE #define SIGNATURE_MAX_SIZE MBEDTLS_ECDSA_MAX_LEN #else #define SIGNATURE_MAX_SIZE MBEDTLS_MPI_MAX_SIZE #endif void mbedtls_x509write_crt_init( mbedtls_x509write_cert *ctx ) { memset( ctx, 0, sizeof( mbedtls_x509write_cert ) ); mbedtls_mpi_init( &ctx->serial ); ctx->version = MBEDTLS_X509_CRT_VERSION_3; } void mbedtls_x509write_crt_free( mbedtls_x509write_cert *ctx ) { mbedtls_mpi_free( &ctx->serial ); mbedtls_asn1_free_named_data_list( &ctx->subject ); mbedtls_asn1_free_named_data_list( &ctx->issuer ); mbedtls_asn1_free_named_data_list( &ctx->extensions ); mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_cert ) ); } void mbedtls_x509write_crt_set_version( mbedtls_x509write_cert *ctx, int version ) { ctx->version = version; } void mbedtls_x509write_crt_set_md_alg( mbedtls_x509write_cert *ctx, mbedtls_md_type_t md_alg ) { ctx->md_alg = md_alg; } void mbedtls_x509write_crt_set_subject_key( mbedtls_x509write_cert *ctx, mbedtls_pk_context *key ) { ctx->subject_key = key; } void mbedtls_x509write_crt_set_issuer_key( mbedtls_x509write_cert *ctx, mbedtls_pk_context *key ) { ctx->issuer_key = key; } int mbedtls_x509write_crt_set_subject_name( mbedtls_x509write_cert *ctx, const char *subject_name ) { return mbedtls_x509_string_to_names( &ctx->subject, subject_name ); } int mbedtls_x509write_crt_set_issuer_name( mbedtls_x509write_cert *ctx, const char *issuer_name ) { return mbedtls_x509_string_to_names( &ctx->issuer, issuer_name ); } int mbedtls_x509write_crt_set_serial( mbedtls_x509write_cert *ctx, const mbedtls_mpi *serial ) { int ret; if( ( ret = mbedtls_mpi_copy( &ctx->serial, serial ) ) != 0 ) return( ret ); return( 0 ); } int mbedtls_x509write_crt_set_validity( mbedtls_x509write_cert *ctx, const char *not_before, const char *not_after ) { if( strlen( not_before ) != MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1 || strlen( not_after ) != MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1 ) { return( MBEDTLS_ERR_X509_BAD_INPUT_DATA ); } strncpy( ctx->not_before, not_before, MBEDTLS_X509_RFC5280_UTC_TIME_LEN ); strncpy( ctx->not_after , not_after , MBEDTLS_X509_RFC5280_UTC_TIME_LEN ); ctx->not_before[MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1] = 'Z'; ctx->not_after[MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1] = 'Z'; return( 0 ); } int mbedtls_x509write_crt_set_extension( mbedtls_x509write_cert *ctx, const char *oid, size_t oid_len, int critical, const unsigned char *val, size_t val_len ) { return( mbedtls_x509_set_extension( &ctx->extensions, oid, oid_len, critical, val, val_len ) ); } int mbedtls_x509write_crt_set_basic_constraints( mbedtls_x509write_cert *ctx, int is_ca, int max_pathlen ) { int ret; unsigned char buf[9]; unsigned char *c = buf + sizeof(buf); size_t len = 0; memset( buf, 0, sizeof(buf) ); if( is_ca && max_pathlen > 127 ) return( MBEDTLS_ERR_X509_BAD_INPUT_DATA ); if( is_ca ) { if( max_pathlen >= 0 ) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, max_pathlen ) ); } MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_bool( &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 ) ); return( mbedtls_x509write_crt_set_extension( ctx, MBEDTLS_OID_BASIC_CONSTRAINTS, MBEDTLS_OID_SIZE( MBEDTLS_OID_BASIC_CONSTRAINTS ), is_ca, buf + sizeof(buf) - len, len ) ); } #if defined(MBEDTLS_SHA1_C) int mbedtls_x509write_crt_set_subject_key_identifier( mbedtls_x509write_cert *ctx ) { int ret; unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */ unsigned char *c = buf + sizeof(buf); size_t len = 0; memset( buf, 0, sizeof(buf) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, ctx->subject_key ) ); ret = mbedtls_sha1_ret( buf + sizeof( buf ) - len, len, buf + sizeof( buf ) - 20 ); if( ret != 0 ) return( ret ); c = buf + sizeof( buf ) - 20; len = 20; 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_OCTET_STRING ) ); return mbedtls_x509write_crt_set_extension( ctx, MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER, MBEDTLS_OID_SIZE( MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER ), 0, buf + sizeof(buf) - len, len ); } int mbedtls_x509write_crt_set_authority_key_identifier( mbedtls_x509write_cert *ctx ) { int ret; unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */ unsigned char *c = buf + sizeof( buf ); size_t len = 0; memset( buf, 0, sizeof(buf) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_pk_write_pubkey( &c, buf, ctx->issuer_key ) ); ret = mbedtls_sha1_ret( buf + sizeof( buf ) - len, len, buf + sizeof( buf ) - 20 ); if( ret != 0 ) return( ret ); c = buf + sizeof( buf ) - 20; len = 20; 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_CONTEXT_SPECIFIC | 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 ) ); return mbedtls_x509write_crt_set_extension( ctx, MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER, MBEDTLS_OID_SIZE( MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER ), 0, buf + sizeof( buf ) - len, len ); } #endif /* MBEDTLS_SHA1_C */ static size_t crt_get_unused_bits_for_named_bitstring( unsigned char bitstring, size_t bit_offset ) { size_t unused_bits; /* Count the unused bits removing trailing 0s */ for( unused_bits = bit_offset; unused_bits < 8; unused_bits++ ) if( ( ( bitstring >> unused_bits ) & 0x1 ) != 0 ) break; return( unused_bits ); } int mbedtls_x509write_crt_set_key_usage( mbedtls_x509write_cert *ctx, unsigned int key_usage ) { unsigned char buf[4], ku; unsigned char *c; int ret; size_t unused_bits; const unsigned int allowed_bits = MBEDTLS_X509_KU_DIGITAL_SIGNATURE | MBEDTLS_X509_KU_NON_REPUDIATION | MBEDTLS_X509_KU_KEY_ENCIPHERMENT | MBEDTLS_X509_KU_DATA_ENCIPHERMENT | MBEDTLS_X509_KU_KEY_AGREEMENT | MBEDTLS_X509_KU_KEY_CERT_SIGN | MBEDTLS_X509_KU_CRL_SIGN; /* Check that nothing other than the allowed flags is set */ if( ( key_usage & ~allowed_bits ) != 0 ) return( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE ); c = buf + 4; ku = (unsigned char)key_usage; unused_bits = crt_get_unused_bits_for_named_bitstring( ku, 1 ); ret = mbedtls_asn1_write_bitstring( &c, buf, &ku, 8 - unused_bits ); if( ret < 0 ) return( ret ); else if( ret < 3 || ret > 4 ) return( MBEDTLS_ERR_X509_INVALID_FORMAT ); ret = mbedtls_x509write_crt_set_extension( ctx, MBEDTLS_OID_KEY_USAGE, MBEDTLS_OID_SIZE( MBEDTLS_OID_KEY_USAGE ), 1, c, (size_t)ret ); if( ret != 0 ) return( ret ); return( 0 ); } int mbedtls_x509write_crt_set_ns_cert_type( mbedtls_x509write_cert *ctx, unsigned char ns_cert_type ) { unsigned char buf[4]; unsigned char *c; size_t unused_bits; int ret; c = buf + 4; unused_bits = crt_get_unused_bits_for_named_bitstring( ns_cert_type, 0 ); ret = mbedtls_asn1_write_bitstring( &c, buf, &ns_cert_type, 8 - unused_bits ); if( ret < 3 || ret > 4 ) return( ret ); ret = mbedtls_x509write_crt_set_extension( ctx, MBEDTLS_OID_NS_CERT_TYPE, MBEDTLS_OID_SIZE( MBEDTLS_OID_NS_CERT_TYPE ), 0, c, (size_t)ret ); if( ret != 0 ) return( ret ); return( 0 ); } static int x509_write_time( unsigned char **p, unsigned char *start, const char *t, size_t size ) { int ret; size_t len = 0; /* * write MBEDTLS_ASN1_UTC_TIME if year < 2050 (2 bytes shorter) */ if( t[0] == '2' && t[1] == '0' && t[2] < '5' ) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, (const unsigned char *) t + 2, size - 2 ) ); 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_UTC_TIME ) ); } else { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, (const unsigned char *) t, size ) ); 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_GENERALIZED_TIME ) ); } return( (int) len ); } int mbedtls_x509write_crt_der( mbedtls_x509write_cert *ctx, unsigned char *buf, size_t size, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; const char *sig_oid; size_t sig_oid_len = 0; unsigned char *c, *c2; unsigned char hash[64]; unsigned char sig[SIGNATURE_MAX_SIZE]; size_t sub_len = 0, pub_len = 0, sig_and_oid_len = 0, sig_len; size_t len = 0; mbedtls_pk_type_t pk_alg; /* * Prepare data to be signed at the end of the target buffer */ c = buf + size; /* Signature algorithm needed in TBS, and later for actual signature */ /* There's no direct way of extracting a signature algorithm * (represented as an element of mbedtls_pk_type_t) from a PK instance. */ if( mbedtls_pk_can_do( ctx->issuer_key, MBEDTLS_PK_RSA ) ) pk_alg = MBEDTLS_PK_RSA; else if( mbedtls_pk_can_do( ctx->issuer_key, MBEDTLS_PK_ECDSA ) ) pk_alg = MBEDTLS_PK_ECDSA; else return( MBEDTLS_ERR_X509_INVALID_ALG ); if( ( ret = mbedtls_oid_get_oid_by_sig_alg( pk_alg, ctx->md_alg, &sig_oid, &sig_oid_len ) ) != 0 ) { return( ret ); } /* * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension */ /* Only for v3 */ if( ctx->version == MBEDTLS_X509_CRT_VERSION_3 ) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, buf, ctx->extensions ) ); 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 ) ); 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_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 3 ) ); } /* * SubjectPublicKeyInfo */ MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_pk_write_pubkey_der( ctx->subject_key, buf, c - buf ) ); c -= pub_len; len += pub_len; /* * Subject ::= Name */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_names( &c, buf, ctx->subject ) ); /* * Validity ::= SEQUENCE { * notBefore Time, * notAfter Time } */ sub_len = 0; MBEDTLS_ASN1_CHK_ADD( sub_len, x509_write_time( &c, buf, ctx->not_after, MBEDTLS_X509_RFC5280_UTC_TIME_LEN ) ); MBEDTLS_ASN1_CHK_ADD( sub_len, x509_write_time( &c, buf, ctx->not_before, MBEDTLS_X509_RFC5280_UTC_TIME_LEN ) ); len += sub_len; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, sub_len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); /* * Issuer ::= Name */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_names( &c, buf, ctx->issuer ) ); /* * Signature ::= AlgorithmIdentifier */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_algorithm_identifier( &c, buf, sig_oid, strlen( sig_oid ), 0 ) ); /* * Serial ::= INTEGER */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_mpi( &c, buf, &ctx->serial ) ); /* * Version ::= INTEGER { v1(0), v2(1), v3(2) } */ /* Can be omitted for v1 */ if( ctx->version != MBEDTLS_X509_CRT_VERSION_1 ) { sub_len = 0; MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, buf, ctx->version ) ); len += sub_len; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, sub_len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 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 ) ); /* * Make signature */ /* Compute hash of CRT. */ if( ( ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash ) ) != 0 ) { return( ret ); } if( ( ret = mbedtls_pk_sign( ctx->issuer_key, ctx->md_alg, hash, 0, sig, &sig_len, f_rng, p_rng ) ) != 0 ) { return( ret ); } /* Move CRT to the front of the buffer to have space * for the signature. */ memmove( buf, c, len ); c = buf + len; /* Add signature at the end of the buffer, * making sure that it doesn't underflow * into the CRT buffer. */ c2 = buf + size; MBEDTLS_ASN1_CHK_ADD( sig_and_oid_len, mbedtls_x509_write_sig( &c2, c, sig_oid, sig_oid_len, sig, sig_len ) ); /* * Memory layout after this step: * * buf c=buf+len c2 buf+size * [CRT0,...,CRTn, UNUSED, ..., UNUSED, SIG0, ..., SIGm] */ /* Move raw CRT to just before the signature. */ c = c2 - len; memmove( c, buf, len ); len += sig_and_oid_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 ); } #define PEM_BEGIN_CRT "-----BEGIN CERTIFICATE-----\n" #define PEM_END_CRT "-----END CERTIFICATE-----\n" #if defined(MBEDTLS_PEM_WRITE_C) int mbedtls_x509write_crt_pem( mbedtls_x509write_cert *crt, unsigned char *buf, size_t size, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; size_t olen; if( ( ret = mbedtls_x509write_crt_der( crt, buf, size, f_rng, p_rng ) ) < 0 ) { return( ret ); } if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CRT, PEM_END_CRT, buf + size - ret, ret, buf, size, &olen ) ) != 0 ) { return( ret ); } return( 0 ); } #endif /* MBEDTLS_PEM_WRITE_C */ #endif /* MBEDTLS_X509_CRT_WRITE_C */