mbedtls/library/x509write_csr.c

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/*
* X.509 Certificate Signing Request writing
*
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* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
*
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* 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
*
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* http://www.apache.org/licenses/LICENSE-2.0
*
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* 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.
*
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* This file is part of mbed TLS (https://tls.mbed.org)
*/
/*
* References:
* - CSRs: PKCS#10 v1.7 aka RFC 2986
* - attributes: PKCS#9 v2.0 aka RFC 2985
*/
#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#if defined(MBEDTLS_X509_CSR_WRITE_C)
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#include "mbedtls/x509_csr.h"
#include "mbedtls/oid.h"
#include "mbedtls/asn1write.h"
#include "mbedtls/platform_util.h"
#include <string.h>
#include <stdlib.h>
#if defined(MBEDTLS_PEM_WRITE_C)
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#include "mbedtls/pem.h"
#endif
void mbedtls_x509write_csr_init( mbedtls_x509write_csr *ctx )
{
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memset( ctx, 0, sizeof( mbedtls_x509write_csr ) );
}
void mbedtls_x509write_csr_free( mbedtls_x509write_csr *ctx )
{
mbedtls_asn1_free_named_data_list( &ctx->subject );
mbedtls_asn1_free_named_data_list( &ctx->extensions );
mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_csr ) );
}
void mbedtls_x509write_csr_set_md_alg( mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg )
{
ctx->md_alg = md_alg;
}
void mbedtls_x509write_csr_set_key( mbedtls_x509write_csr *ctx, mbedtls_pk_context *key )
{
ctx->key = key;
}
int mbedtls_x509write_csr_set_subject_name( mbedtls_x509write_csr *ctx,
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const char *subject_name )
{
return mbedtls_x509_string_to_names( &ctx->subject, subject_name );
}
int mbedtls_x509write_csr_set_extension( mbedtls_x509write_csr *ctx,
const char *oid, size_t oid_len,
const unsigned char *val, size_t val_len )
{
return mbedtls_x509_set_extension( &ctx->extensions, oid, oid_len,
0, val, val_len );
}
static size_t csr_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_csr_set_key_usage( mbedtls_x509write_csr *ctx, unsigned char key_usage )
{
unsigned char buf[4];
unsigned char *c;
size_t unused_bits;
int ret;
c = buf + 4;
unused_bits = csr_get_unused_bits_for_named_bitstring( key_usage, 0 );
ret = mbedtls_asn1_write_bitstring( &c, buf, &key_usage, 8 - unused_bits );
if( ret < 0 )
return( ret );
else if( ret < 3 || ret > 4 )
return( MBEDTLS_ERR_X509_INVALID_FORMAT );
ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_KEY_USAGE,
MBEDTLS_OID_SIZE( MBEDTLS_OID_KEY_USAGE ),
c, (size_t)ret );
if( ret != 0 )
return( ret );
return( 0 );
}
int mbedtls_x509write_csr_set_ns_cert_type( mbedtls_x509write_csr *ctx,
unsigned char ns_cert_type )
{
unsigned char buf[4];
unsigned char *c;
size_t unused_bits;
int ret;
c = buf + 4;
unused_bits = csr_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 < 0 )
return( ret );
else if( ret < 3 || ret > 4 )
return( ret );
ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_NS_CERT_TYPE,
MBEDTLS_OID_SIZE( MBEDTLS_OID_NS_CERT_TYPE ),
c, (size_t)ret );
if( ret != 0 )
return( ret );
return( 0 );
}
int mbedtls_x509write_csr_der( mbedtls_x509write_csr *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[MBEDTLS_MPI_MAX_SIZE];
unsigned char tmp_buf[2048];
size_t 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 in tmp_buf
*/
c = tmp_buf + sizeof( tmp_buf );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, tmp_buf, ctx->extensions ) );
if( len )
{
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SET ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( &c, tmp_buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ,
MBEDTLS_OID_SIZE( MBEDTLS_OID_PKCS9_CSR_EXT_REQ ) ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE ) );
}
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_CONTEXT_SPECIFIC ) );
MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_pk_write_pubkey_der( ctx->key,
tmp_buf, c - tmp_buf ) );
c -= pub_len;
len += pub_len;
/*
* Subject ::= Name
*/
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_names( &c, tmp_buf, ctx->subject ) );
/*
* Version ::= INTEGER { v1(0), v2(1), v3(2) }
*/
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, tmp_buf, 0 ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE ) );
/*
* Prepare signature
*/
mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash );
if( ( ret = mbedtls_pk_sign( ctx->key, ctx->md_alg, hash, 0, sig, &sig_len,
f_rng, p_rng ) ) != 0 )
{
return( ret );
}
if( mbedtls_pk_can_do( ctx->key, MBEDTLS_PK_RSA ) )
pk_alg = MBEDTLS_PK_RSA;
else if( mbedtls_pk_can_do( ctx->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 );
}
/*
* Write data to output buffer
*/
c2 = buf + size;
MBEDTLS_ASN1_CHK_ADD( sig_and_oid_len, mbedtls_x509_write_sig( &c2, buf,
sig_oid, sig_oid_len, sig, sig_len ) );
if( len > (size_t)( c2 - buf ) )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
c2 -= len;
memcpy( c2, c, len );
len += sig_and_oid_len;
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c2, buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c2, buf, MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE ) );
return( (int) len );
}
#define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n"
#define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n"
#if defined(MBEDTLS_PEM_WRITE_C)
int mbedtls_x509write_csr_pem( mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
unsigned char output_buf[4096];
size_t olen = 0;
if( ( ret = mbedtls_x509write_csr_der( ctx, output_buf, sizeof(output_buf),
f_rng, p_rng ) ) < 0 )
{
return( ret );
}
if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CSR, PEM_END_CSR,
output_buf + sizeof(output_buf) - ret,
ret, buf, size, &olen ) ) != 0 )
{
return( ret );
}
return( 0 );
}
#endif /* MBEDTLS_PEM_WRITE_C */
#endif /* MBEDTLS_X509_CSR_WRITE_C */