/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:4;coding:utf-8 -*-│ │ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │ ╞══════════════════════════════════════════════════════════════════════════════╡ │ Copyright The Mbed TLS Contributors │ │ │ │ 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. │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "third_party/mbedtls/asn1write.h" #include "third_party/mbedtls/common.h" #include "third_party/mbedtls/error.h" #include "third_party/mbedtls/oid.h" #include "third_party/mbedtls/pem.h" #include "third_party/mbedtls/platform.h" #include "third_party/mbedtls/sha1.h" #include "third_party/mbedtls/x509_crt.h" asm(".ident\t\"\\n\\n\ Mbed TLS (Apache 2.0)\\n\ Copyright ARM Limited\\n\ Copyright Mbed TLS Contributors\""); asm(".include \"libc/disclaimer.inc\""); /* * X.509 certificate writing * * 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: * - 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_X509_CRT_WRITE_C) /** * \brief Initialize a CRT writing context * * \param ctx CRT context to initialize */ void mbedtls_x509write_crt_init( mbedtls_x509write_cert *ctx ) { mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_cert ) ); mbedtls_mpi_init( &ctx->serial ); ctx->version = MBEDTLS_X509_CRT_VERSION_3; } /** * \brief Free the contents of a CRT write context * * \param ctx CRT context to free */ 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 ) ); } /** * \brief Set the verion for a Certificate * Default: MBEDTLS_X509_CRT_VERSION_3 * * \param ctx CRT context to use * \param version version to set (MBEDTLS_X509_CRT_VERSION_1, MBEDTLS_X509_CRT_VERSION_2 or * MBEDTLS_X509_CRT_VERSION_3) */ void mbedtls_x509write_crt_set_version( mbedtls_x509write_cert *ctx, int version ) { ctx->version = version; } /** * \brief Set the MD algorithm to use for the signature * (e.g. MBEDTLS_MD_SHA1) * * \param ctx CRT context to use * \param md_alg MD algorithm to use */ void mbedtls_x509write_crt_set_md_alg( mbedtls_x509write_cert *ctx, mbedtls_md_type_t md_alg ) { ctx->md_alg = md_alg; } /** * \brief Set the subject public key for the certificate * * \param ctx CRT context to use * \param key public key to include */ void mbedtls_x509write_crt_set_subject_key( mbedtls_x509write_cert *ctx, mbedtls_pk_context *key ) { ctx->subject_key = key; } /** * \brief Set the issuer key used for signing the certificate * * \param ctx CRT context to use * \param key private key to sign with */ void mbedtls_x509write_crt_set_issuer_key( mbedtls_x509write_cert *ctx, mbedtls_pk_context *key ) { ctx->issuer_key = key; } /** * \brief Set the subject name for a Certificate * Subject names should contain a comma-separated list * of OID types and values: * e.g. "C=UK,O=ARM,CN=mbed TLS Server 1" * * \param ctx CRT context to use * \param subject_name subject name to set * * \return 0 if subject name was parsed successfully, or * a specific error code */ 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 ); } /** * \brief Set the issuer name for a Certificate * Issuer names should contain a comma-separated list * of OID types and values: * e.g. "C=UK,O=ARM,CN=mbed TLS CA" * * \param ctx CRT context to use * \param issuer_name issuer name to set * * \return 0 if issuer name was parsed successfully, or * a specific error code */ 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 ); } /** * \brief Set the serial number for a Certificate. * * \param ctx CRT context to use * \param serial serial number to set * * \return 0 if successful */ int mbedtls_x509write_crt_set_serial( mbedtls_x509write_cert *ctx, const mbedtls_mpi *serial ) { int ret = MBEDTLS_ERR_THIS_CORRUPTION; if( ( ret = mbedtls_mpi_copy( &ctx->serial, serial ) ) != 0 ) return( ret ); return( 0 ); } /** * \brief Set the validity period for a Certificate * Timestamps should be in string format for UTC timezone * i.e. "YYYYMMDDhhmmss" * e.g. "20131231235959" for December 31st 2013 * at 23:59:59 * * \param ctx CRT context to use * \param not_before not_before timestamp * \param not_after not_after timestamp * * \return 0 if timestamp was parsed successfully, or * a specific error code */ 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 ); } /** * \brief Generic function to add to or replace an extension in the * CRT * * \param ctx CRT context to use * \param oid OID of the extension * \param oid_len length of the OID * \param critical if the extension is critical (per the RFC's definition) * \param val value of the extension OCTET STRING * \param val_len length of the value data * * \return 0 if successful, or a MBEDTLS_ERR_X509_ALLOC_FAILED */ 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 ) ); } /** * \brief Set the basicConstraints extension for a CRT * * \param ctx CRT context to use * \param is_ca is this a CA certificate * \param max_pathlen maximum length of certificate chains below this * certificate (only for CA certificates, -1 is * inlimited) * * \return 0 if successful, or a MBEDTLS_ERR_X509_ALLOC_FAILED */ int mbedtls_x509write_crt_set_basic_constraints( mbedtls_x509write_cert *ctx, int is_ca, int max_pathlen ) { int ret = MBEDTLS_ERR_THIS_CORRUPTION; unsigned char buf[9]; unsigned char *c = buf + sizeof(buf); size_t len = 0; mbedtls_platform_zeroize( buf, 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) /** * \brief Set the subjectKeyIdentifier extension for a CRT * Requires that mbedtls_x509write_crt_set_subject_key() has been * called before * * \param ctx CRT context to use * * \return 0 if successful, or a MBEDTLS_ERR_X509_ALLOC_FAILED */ int mbedtls_x509write_crt_set_subject_key_identifier( mbedtls_x509write_cert *ctx ) { int ret = MBEDTLS_ERR_THIS_CORRUPTION; unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */ unsigned char *c = buf + sizeof(buf); size_t len = 0; mbedtls_platform_zeroize( buf, 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 ); } /** * \brief Set the authorityKeyIdentifier extension for a CRT * Requires that mbedtls_x509write_crt_set_issuer_key() has been * called before * * \param ctx CRT context to use * * \return 0 if successful, or a MBEDTLS_ERR_X509_ALLOC_FAILED */ int mbedtls_x509write_crt_set_authority_key_identifier( mbedtls_x509write_cert *ctx ) { int ret = MBEDTLS_ERR_THIS_CORRUPTION; unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */ unsigned char *c = buf + sizeof( buf ); size_t len = 0; mbedtls_platform_zeroize( buf, 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 */ /** * \brief Set the Key Usage Extension flags * (e.g. MBEDTLS_X509_KU_DIGITAL_SIGNATURE | MBEDTLS_X509_KU_KEY_CERT_SIGN) * * \param ctx CRT context to use * \param key_usage key usage flags to set * * \return 0 if successful, or MBEDTLS_ERR_X509_ALLOC_FAILED */ int mbedtls_x509write_crt_set_key_usage( mbedtls_x509write_cert *ctx, unsigned int key_usage ) { unsigned char buf[5], ku[2]; unsigned char *c; int ret = MBEDTLS_ERR_THIS_CORRUPTION; 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 | MBEDTLS_X509_KU_ENCIPHER_ONLY | MBEDTLS_X509_KU_DECIPHER_ONLY; /* Check that nothing other than the allowed flags is set */ if( ( key_usage & ~allowed_bits ) != 0 ) return( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE ); c = buf + 5; ku[0] = (unsigned char)( key_usage ); ku[1] = (unsigned char)( key_usage >> 8 ); ret = mbedtls_asn1_write_named_bitstring( &c, buf, ku, 9 ); if( ret < 0 ) return( ret ); else if( ret < 3 || ret > 5 ) 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 ); } /** * \brief Set the Netscape Cert Type flags * (e.g. MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT | MBEDTLS_X509_NS_CERT_TYPE_EMAIL) * * \param ctx CRT context to use * \param ns_cert_type Netscape Cert Type flags to set * * \return 0 if successful, or MBEDTLS_ERR_X509_ALLOC_FAILED */ int mbedtls_x509write_crt_set_ns_cert_type( mbedtls_x509write_cert *ctx, unsigned char ns_cert_type ) { unsigned char buf[4]; unsigned char *c; int ret = MBEDTLS_ERR_THIS_CORRUPTION; c = buf + 4; ret = mbedtls_asn1_write_named_bitstring( &c, buf, &ns_cert_type, 8 ); 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 ); } /** * Writes Extended Key Usage section to certificate. * * @see mbedtls_x509write_crt_set_ns_cert_type() * @see RFC5280 §4.2.1.12 */ int mbedtls_x509write_crt_set_ext_key_usage(mbedtls_x509write_cert *ctx, int ns_cert_type) { int ret; size_t len; unsigned char buf[256]; unsigned char *c; if (!ns_cert_type) return 0; if (ns_cert_type & ~(MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT | MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER | MBEDTLS_X509_NS_CERT_TYPE_EMAIL)) { return MBEDTLS_ERR_X509_BAD_INPUT_DATA; } len = 0; c = buf + sizeof(buf); mbedtls_platform_zeroize(buf, sizeof(buf)); if (ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid(&c, buf, MBEDTLS_OID_CLIENT_AUTH, MBEDTLS_OID_SIZE(MBEDTLS_OID_CLIENT_AUTH))); } if (ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid(&c, buf, MBEDTLS_OID_SERVER_AUTH, MBEDTLS_OID_SIZE(MBEDTLS_OID_SERVER_AUTH))); } if (ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_EMAIL) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid(&c, buf, MBEDTLS_OID_EMAIL_PROTECTION, MBEDTLS_OID_SIZE(MBEDTLS_OID_EMAIL_PROTECTION))); } 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_EXTENDED_KEY_USAGE, MBEDTLS_OID_SIZE(MBEDTLS_OID_EXTENDED_KEY_USAGE), false, buf + sizeof(buf) - len, len); } static int x509_write_time( unsigned char **p, unsigned char *start, const char *t, size_t size ) { int ret = MBEDTLS_ERR_THIS_CORRUPTION; 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 ); } /** * \brief Write a built up certificate to a X509 DER structure * Note: data is written at the end of the buffer! Use the * return value to determine where you should start * using the buffer * * \param ctx certificate to write away * \param buf buffer to write to * \param size size of the buffer * \param f_rng RNG function (for signature, see note) * \param p_rng RNG parameter * * \return length of data written if successful, or a specific * error code * * \note f_rng may be NULL if RSA is used for signature and the * signature is made offline (otherwise f_rng is desirable * for countermeasures against timing attacks). * ECDSA signatures always require a non-NULL f_rng. */ 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 = MBEDTLS_ERR_THIS_CORRUPTION; const char *sig_oid; size_t sig_oid_len = 0; unsigned char *c, *c2; unsigned char hash[64]; unsigned char sig[MBEDTLS_PK_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" /** * \brief Write a built up certificate to a X509 PEM string * * \param ctx certificate to write away * \param buf buffer to write to * \param size size of the buffer * \param f_rng RNG function (for signature, see note) * \param p_rng RNG parameter * * \return 0 if successful, or a specific error code * * \note f_rng may be NULL if RSA is used for signature and the * signature is made offline (otherwise f_rng is desirable * for countermeasures against timing attacks). * ECDSA signatures always require a non-NULL f_rng. */ 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 = MBEDTLS_ERR_THIS_CORRUPTION; 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_X509_CRT_WRITE_C */