385 lines
12 KiB
C
385 lines
12 KiB
C
/*
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* X.509 Certificate Signing Request writing
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*
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* This file is provided under the Apache License 2.0, or the
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* GNU General Public License v2.0 or later.
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*
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* **********
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* Apache License 2.0:
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* **********
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*
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* **********
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* GNU General Public License v2.0 or later:
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* **********
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*/
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/*
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* References:
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* - CSRs: PKCS#10 v1.7 aka RFC 2986
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* - attributes: PKCS#9 v2.0 aka RFC 2985
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_X509_CSR_WRITE_C)
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#include "mbedtls/x509_csr.h"
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#include "mbedtls/oid.h"
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#include "mbedtls/asn1write.h"
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#include "mbedtls/platform_util.h"
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#include <string.h>
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#include <stdlib.h>
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#if defined(MBEDTLS_PEM_WRITE_C)
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#include "mbedtls/pem.h"
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#endif
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/*
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* For the currently used signature algorithms the buffer to store any signature
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* must be at least of size MAX(MBEDTLS_ECDSA_MAX_LEN, MBEDTLS_MPI_MAX_SIZE)
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*/
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#if MBEDTLS_ECDSA_MAX_LEN > MBEDTLS_MPI_MAX_SIZE
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#define SIGNATURE_MAX_SIZE MBEDTLS_ECDSA_MAX_LEN
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#else
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#define SIGNATURE_MAX_SIZE MBEDTLS_MPI_MAX_SIZE
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#endif
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#if defined(MBEDTLS_PLATFORM_C)
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#include "mbedtls/platform.h"
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#else
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#include <stdlib.h>
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#define mbedtls_calloc calloc
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#define mbedtls_free free
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#endif
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void mbedtls_x509write_csr_init( mbedtls_x509write_csr *ctx )
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{
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memset( ctx, 0, sizeof( mbedtls_x509write_csr ) );
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}
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void mbedtls_x509write_csr_free( mbedtls_x509write_csr *ctx )
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{
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mbedtls_asn1_free_named_data_list( &ctx->subject );
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mbedtls_asn1_free_named_data_list( &ctx->extensions );
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mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_csr ) );
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}
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void mbedtls_x509write_csr_set_md_alg( mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg )
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{
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ctx->md_alg = md_alg;
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}
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void mbedtls_x509write_csr_set_key( mbedtls_x509write_csr *ctx, mbedtls_pk_context *key )
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{
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ctx->key = key;
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}
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int mbedtls_x509write_csr_set_subject_name( mbedtls_x509write_csr *ctx,
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const char *subject_name )
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{
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return mbedtls_x509_string_to_names( &ctx->subject, subject_name );
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}
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int mbedtls_x509write_csr_set_extension( mbedtls_x509write_csr *ctx,
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const char *oid, size_t oid_len,
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const unsigned char *val, size_t val_len )
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{
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return mbedtls_x509_set_extension( &ctx->extensions, oid, oid_len,
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0, val, val_len );
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}
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static size_t csr_get_unused_bits_for_named_bitstring( unsigned char bitstring,
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size_t bit_offset )
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{
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size_t unused_bits;
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/* Count the unused bits removing trailing 0s */
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for( unused_bits = bit_offset; unused_bits < 8; unused_bits++ )
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if( ( ( bitstring >> unused_bits ) & 0x1 ) != 0 )
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break;
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return( unused_bits );
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}
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int mbedtls_x509write_csr_set_key_usage( mbedtls_x509write_csr *ctx, unsigned char key_usage )
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{
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unsigned char buf[4];
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unsigned char *c;
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size_t unused_bits;
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int ret;
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c = buf + 4;
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unused_bits = csr_get_unused_bits_for_named_bitstring( key_usage, 0 );
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ret = mbedtls_asn1_write_bitstring( &c, buf, &key_usage, 8 - unused_bits );
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if( ret < 0 )
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return( ret );
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else if( ret < 3 || ret > 4 )
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return( MBEDTLS_ERR_X509_INVALID_FORMAT );
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ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_KEY_USAGE,
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MBEDTLS_OID_SIZE( MBEDTLS_OID_KEY_USAGE ),
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c, (size_t)ret );
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if( ret != 0 )
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return( ret );
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return( 0 );
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}
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int mbedtls_x509write_csr_set_ns_cert_type( mbedtls_x509write_csr *ctx,
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unsigned char ns_cert_type )
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{
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unsigned char buf[4];
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unsigned char *c;
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size_t unused_bits;
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int ret;
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c = buf + 4;
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unused_bits = csr_get_unused_bits_for_named_bitstring( ns_cert_type, 0 );
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ret = mbedtls_asn1_write_bitstring( &c,
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buf,
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&ns_cert_type,
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8 - unused_bits );
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if( ret < 0 )
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return( ret );
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else if( ret < 3 || ret > 4 )
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return( ret );
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ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_NS_CERT_TYPE,
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MBEDTLS_OID_SIZE( MBEDTLS_OID_NS_CERT_TYPE ),
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c, (size_t)ret );
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if( ret != 0 )
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return( ret );
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return( 0 );
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}
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static int x509write_csr_der_internal( mbedtls_x509write_csr *ctx,
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unsigned char *buf,
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size_t size,
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unsigned char *sig,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng )
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{
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int ret;
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const char *sig_oid;
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size_t sig_oid_len = 0;
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unsigned char *c, *c2;
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unsigned char hash[64];
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size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
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size_t len = 0;
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mbedtls_pk_type_t pk_alg;
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/* Write the CSR backwards starting from the end of buf */
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c = buf + size;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, buf,
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ctx->extensions ) );
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if( len )
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{
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_tag(
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&c, buf,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_tag(
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&c, buf,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_oid(
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&c, buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ,
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MBEDTLS_OID_SIZE( MBEDTLS_OID_PKCS9_CSR_EXT_REQ ) ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_tag(
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&c, buf,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
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}
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_tag(
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&c, buf,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) );
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MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_pk_write_pubkey_der( ctx->key,
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buf, c - buf ) );
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c -= pub_len;
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len += pub_len;
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/*
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* Subject ::= Name
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*/
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_names( &c, buf,
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ctx->subject ) );
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/*
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* Version ::= INTEGER { v1(0), v2(1), v3(2) }
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*/
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 0 ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_tag(
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&c, buf,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
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/*
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* Sign the written CSR data into the sig buffer
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* Note: hash errors can happen only after an internal error
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*/
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ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash );
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if( ret != 0 )
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return( ret );
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if( ( ret = mbedtls_pk_sign( ctx->key, ctx->md_alg, hash, 0, sig, &sig_len,
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f_rng, p_rng ) ) != 0 )
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{
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return( ret );
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}
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if( mbedtls_pk_can_do( ctx->key, MBEDTLS_PK_RSA ) )
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pk_alg = MBEDTLS_PK_RSA;
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else if( mbedtls_pk_can_do( ctx->key, MBEDTLS_PK_ECDSA ) )
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pk_alg = MBEDTLS_PK_ECDSA;
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else
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return( MBEDTLS_ERR_X509_INVALID_ALG );
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if( ( ret = mbedtls_oid_get_oid_by_sig_alg( pk_alg, ctx->md_alg,
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&sig_oid, &sig_oid_len ) ) != 0 )
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{
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return( ret );
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}
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/*
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* Move the written CSR data to the start of buf to create space for
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* writing the signature into buf.
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*/
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memmove( buf, c, len );
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/*
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* Write sig and its OID into buf backwards from the end of buf.
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* Note: mbedtls_x509_write_sig will check for c2 - ( buf + len ) < sig_len
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* and return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if needed.
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*/
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c2 = buf + size;
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MBEDTLS_ASN1_CHK_ADD( sig_and_oid_len,
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mbedtls_x509_write_sig( &c2, buf + len, sig_oid, sig_oid_len,
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sig, sig_len ) );
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/*
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* Compact the space between the CSR data and signature by moving the
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* CSR data to the start of the signature.
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*/
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c2 -= len;
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memmove( c2, buf, len );
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/* ASN encode the total size and tag the CSR data with it. */
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len += sig_and_oid_len;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c2, buf, len ) );
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MBEDTLS_ASN1_CHK_ADD( len,
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mbedtls_asn1_write_tag(
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&c2, buf,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
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/* Zero the unused bytes at the start of buf */
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memset( buf, 0, c2 - buf);
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return( (int) len );
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}
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int mbedtls_x509write_csr_der( mbedtls_x509write_csr *ctx, unsigned char *buf,
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size_t size,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng )
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{
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int ret;
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unsigned char *sig;
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if( ( sig = mbedtls_calloc( 1, SIGNATURE_MAX_SIZE ) ) == NULL )
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{
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return( MBEDTLS_ERR_X509_ALLOC_FAILED );
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}
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ret = x509write_csr_der_internal( ctx, buf, size, sig, f_rng, p_rng );
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mbedtls_free( sig );
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return( ret );
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}
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#define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n"
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#define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n"
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#if defined(MBEDTLS_PEM_WRITE_C)
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int mbedtls_x509write_csr_pem( mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size,
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int (*f_rng)(void *, unsigned char *, size_t),
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void *p_rng )
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{
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int ret;
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unsigned char output_buf[4096];
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size_t olen = 0;
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if( ( ret = mbedtls_x509write_csr_der( ctx, output_buf, sizeof(output_buf),
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f_rng, p_rng ) ) < 0 )
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{
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return( ret );
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}
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if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CSR, PEM_END_CSR,
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output_buf + sizeof(output_buf) - ret,
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ret, buf, size, &olen ) ) != 0 )
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{
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return( ret );
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}
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return( 0 );
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}
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#endif /* MBEDTLS_PEM_WRITE_C */
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#endif /* MBEDTLS_X509_CSR_WRITE_C */
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