mbedtls/include/mbedtls/x509_crt.h
Manuel Pégourié-Gonnard 05e464dff7 Merge branch 'development' into iotssl-1381-x509-verify-refactor-restricted
* development: (557 commits)
  Add attribution for #1351 report
  Adapt version_features.c
  Note incompatibility of truncated HMAC extension in ChangeLog
  Add LinkLibraryDependencies to VS2010 app template
  Add ChangeLog entry for PR #1382
  MD: Make deprecated functions not inline
  Add ChangeLog entry for PR #1384
  Have Visual Studio handle linking to mbedTLS.lib internally
  Mention in ChangeLog that this fixes #1351
  Add issue number to ChangeLog
  Note in the changelog that this fixes an interoperability issue.
  Style fix in ChangeLog
  Add ChangeLog entries for PR #1168 and #1362
  Add ChangeLog entry for PR #1165
  ctr_drbg: Typo fix in the file description comment.
  dhm: Fix typo in RFC 5114 constants
  tests_suite_pkparse: new PKCS8-v2 keys with PRF != SHA1
  data_files/pkcs8-v2: add keys generated with PRF != SHA1
  tests/pkcs5/pbkdf2_hmac: extend array to accommodate longer results
  tests/pkcs5/pbkdf2_hmac: add unit tests for additional SHA algorithms
  ...
2018-03-05 11:55:38 +01:00

671 lines
26 KiB
C

/**
* \file x509_crt.h
*
* \brief X.509 certificate parsing and writing
*/
/*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* 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.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#ifndef MBEDTLS_X509_CRT_H
#define MBEDTLS_X509_CRT_H
#if !defined(MBEDTLS_CONFIG_FILE)
#include "config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif
#include "x509.h"
#include "x509_crl.h"
/**
* \addtogroup x509_module
* \{
*/
#ifdef __cplusplus
extern "C" {
#endif
/**
* \name Structures and functions for parsing and writing X.509 certificates
* \{
*/
/**
* Container for an X.509 certificate. The certificate may be chained.
*/
typedef struct mbedtls_x509_crt
{
mbedtls_x509_buf raw; /**< The raw certificate data (DER). */
mbedtls_x509_buf tbs; /**< The raw certificate body (DER). The part that is To Be Signed. */
int version; /**< The X.509 version. (1=v1, 2=v2, 3=v3) */
mbedtls_x509_buf serial; /**< Unique id for certificate issued by a specific CA. */
mbedtls_x509_buf sig_oid; /**< Signature algorithm, e.g. sha1RSA */
mbedtls_x509_buf issuer_raw; /**< The raw issuer data (DER). Used for quick comparison. */
mbedtls_x509_buf subject_raw; /**< The raw subject data (DER). Used for quick comparison. */
mbedtls_x509_name issuer; /**< The parsed issuer data (named information object). */
mbedtls_x509_name subject; /**< The parsed subject data (named information object). */
mbedtls_x509_time valid_from; /**< Start time of certificate validity. */
mbedtls_x509_time valid_to; /**< End time of certificate validity. */
mbedtls_pk_context pk; /**< Container for the public key context. */
mbedtls_x509_buf issuer_id; /**< Optional X.509 v2/v3 issuer unique identifier. */
mbedtls_x509_buf subject_id; /**< Optional X.509 v2/v3 subject unique identifier. */
mbedtls_x509_buf v3_ext; /**< Optional X.509 v3 extensions. */
mbedtls_x509_sequence subject_alt_names; /**< Optional list of Subject Alternative Names (Only dNSName supported). */
int ext_types; /**< Bit string containing detected and parsed extensions */
int ca_istrue; /**< Optional Basic Constraint extension value: 1 if this certificate belongs to a CA, 0 otherwise. */
int max_pathlen; /**< Optional Basic Constraint extension value: The maximum path length to the root certificate. Path length is 1 higher than RFC 5280 'meaning', so 1+ */
unsigned int key_usage; /**< Optional key usage extension value: See the values in x509.h */
mbedtls_x509_sequence ext_key_usage; /**< Optional list of extended key usage OIDs. */
unsigned char ns_cert_type; /**< Optional Netscape certificate type extension value: See the values in x509.h */
mbedtls_x509_buf sig; /**< Signature: hash of the tbs part signed with the private key. */
mbedtls_md_type_t sig_md; /**< Internal representation of the MD algorithm of the signature algorithm, e.g. MBEDTLS_MD_SHA256 */
mbedtls_pk_type_t sig_pk; /**< Internal representation of the Public Key algorithm of the signature algorithm, e.g. MBEDTLS_PK_RSA */
void *sig_opts; /**< Signature options to be passed to mbedtls_pk_verify_ext(), e.g. for RSASSA-PSS */
struct mbedtls_x509_crt *next; /**< Next certificate in the CA-chain. */
}
mbedtls_x509_crt;
/**
* Build flag from an algorithm/curve identifier (pk, md, ecp)
* Since 0 is always XXX_NONE, ignore it.
*/
#define MBEDTLS_X509_ID_FLAG( id ) ( 1 << ( id - 1 ) )
/**
* Security profile for certificate verification.
*
* All lists are bitfields, built by ORing flags from MBEDTLS_X509_ID_FLAG().
*/
typedef struct
{
uint32_t allowed_mds; /**< MDs for signatures */
uint32_t allowed_pks; /**< PK algs for signatures */
uint32_t allowed_curves; /**< Elliptic curves for ECDSA */
uint32_t rsa_min_bitlen; /**< Minimum size for RSA keys */
}
mbedtls_x509_crt_profile;
#define MBEDTLS_X509_CRT_VERSION_1 0
#define MBEDTLS_X509_CRT_VERSION_2 1
#define MBEDTLS_X509_CRT_VERSION_3 2
#define MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN 32
#define MBEDTLS_X509_RFC5280_UTC_TIME_LEN 15
#if !defined( MBEDTLS_X509_MAX_FILE_PATH_LEN )
#define MBEDTLS_X509_MAX_FILE_PATH_LEN 512
#endif
/**
* Container for writing a certificate (CRT)
*/
typedef struct mbedtls_x509write_cert
{
int version;
mbedtls_mpi serial;
mbedtls_pk_context *subject_key;
mbedtls_pk_context *issuer_key;
mbedtls_asn1_named_data *subject;
mbedtls_asn1_named_data *issuer;
mbedtls_md_type_t md_alg;
char not_before[MBEDTLS_X509_RFC5280_UTC_TIME_LEN + 1];
char not_after[MBEDTLS_X509_RFC5280_UTC_TIME_LEN + 1];
mbedtls_asn1_named_data *extensions;
}
mbedtls_x509write_cert;
#if defined(MBEDTLS_X509_CRT_PARSE_C)
/**
* Default security profile. Should provide a good balance between security
* and compatibility with current deployments.
*/
extern const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_default;
/**
* Expected next default profile. Recommended for new deployments.
* Currently targets a 128-bit security level, except for RSA-2048.
*/
extern const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_next;
/**
* NSA Suite B profile.
*/
extern const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_suiteb;
/**
* \brief Parse a single DER formatted certificate and add it
* to the chained list.
*
* \param chain points to the start of the chain
* \param buf buffer holding the certificate DER data
* \param buflen size of the buffer
*
* \return 0 if successful, or a specific X509 or PEM error code
*/
int mbedtls_x509_crt_parse_der( mbedtls_x509_crt *chain, const unsigned char *buf,
size_t buflen );
/**
* \brief Parse one or more certificates and add them
* to the chained list. Parses permissively. If some
* certificates can be parsed, the result is the number
* of failed certificates it encountered. If none complete
* correctly, the first error is returned.
*
* \param chain points to the start of the chain
* \param buf buffer holding the certificate data in PEM or DER format
* \param buflen size of the buffer
* (including the terminating null byte for PEM data)
*
* \return 0 if all certificates parsed successfully, a positive number
* if partly successful or a specific X509 or PEM error code
*/
int mbedtls_x509_crt_parse( mbedtls_x509_crt *chain, const unsigned char *buf, size_t buflen );
#if defined(MBEDTLS_FS_IO)
/**
* \brief Load one or more certificates and add them
* to the chained list. Parses permissively. If some
* certificates can be parsed, the result is the number
* of failed certificates it encountered. If none complete
* correctly, the first error is returned.
*
* \param chain points to the start of the chain
* \param path filename to read the certificates from
*
* \return 0 if all certificates parsed successfully, a positive number
* if partly successful or a specific X509 or PEM error code
*/
int mbedtls_x509_crt_parse_file( mbedtls_x509_crt *chain, const char *path );
/**
* \brief Load one or more certificate files from a path and add them
* to the chained list. Parses permissively. If some
* certificates can be parsed, the result is the number
* of failed certificates it encountered. If none complete
* correctly, the first error is returned.
*
* \param chain points to the start of the chain
* \param path directory / folder to read the certificate files from
*
* \return 0 if all certificates parsed successfully, a positive number
* if partly successful or a specific X509 or PEM error code
*/
int mbedtls_x509_crt_parse_path( mbedtls_x509_crt *chain, const char *path );
#endif /* MBEDTLS_FS_IO */
/**
* \brief Returns an informational string about the
* certificate.
*
* \param buf Buffer to write to
* \param size Maximum size of buffer
* \param prefix A line prefix
* \param crt The X509 certificate to represent
*
* \return The length of the string written (not including the
* terminated nul byte), or a negative error code.
*/
int mbedtls_x509_crt_info( char *buf, size_t size, const char *prefix,
const mbedtls_x509_crt *crt );
/**
* \brief Returns an informational string about the
* verification status of a certificate.
*
* \param buf Buffer to write to
* \param size Maximum size of buffer
* \param prefix A line prefix
* \param flags Verification flags created by mbedtls_x509_crt_verify()
*
* \return The length of the string written (not including the
* terminated nul byte), or a negative error code.
*/
int mbedtls_x509_crt_verify_info( char *buf, size_t size, const char *prefix,
uint32_t flags );
/**
* \brief Verify the certificate signature
*
* The verify callback is a user-supplied callback that
* can clear / modify / add flags for a certificate. If set,
* the verification callback is called for each
* certificate in the chain (from the trust-ca down to the
* presented crt). The parameters for the callback are:
* (void *parameter, mbedtls_x509_crt *crt, int certificate_depth,
* int *flags). With the flags representing current flags for
* that specific certificate and the certificate depth from
* the bottom (Peer cert depth = 0).
*
* All flags left after returning from the callback
* are also returned to the application. The function should
* return 0 for anything (including invalid certificates)
* other than fatal error, as a non-zero return code
* immediately aborts the verification process. For fatal
* errors, a specific error code should be used (different
* from MBEDTLS_ERR_X509_CERT_VERIFY_FAILED which should not
* be returned at this point), or MBEDTLS_ERR_X509_FATAL_ERROR
* can be used if no better code is available.
*
* \note In case verification failed, the results can be displayed
* using \c mbedtls_x509_crt_verify_info()
*
* \note Same as \c mbedtls_x509_crt_verify_with_profile() with the
* default security profile.
*
* \note It is your responsibility to provide up-to-date CRLs for
* all trusted CAs. If no CRL is provided for the CA that was
* used to sign the certificate, CRL verification is skipped
* silently, that is *without* setting any flag.
*
* \note The \c trust_ca list can contain two types of certificates:
* (1) those of trusted root CAs, so that certificates
* chaining up to those CAs will be trusted, and (2)
* self-signed end-entity certificates to be trusted (for
* specific peers you know) - in that case, the self-signed
* certificate doesn't need to have the CA bit set.
*
* \param crt a certificate (chain) to be verified
* \param trust_ca the list of trusted CAs (see note above)
* \param ca_crl the list of CRLs for trusted CAs (see note above)
* \param cn expected Common Name (can be set to
* NULL if the CN must not be verified)
* \param flags result of the verification
* \param f_vrfy verification function
* \param p_vrfy verification parameter
*
* \return 0 (and flags set to 0) if the chain was verified and valid,
* MBEDTLS_ERR_X509_CERT_VERIFY_FAILED if the chain was verified
* but found to be invalid, in which case *flags will have one
* or more MBEDTLS_X509_BADCERT_XXX or MBEDTLS_X509_BADCRL_XXX
* flags set, or another error (and flags set to 0xffffffff)
* in case of a fatal error encountered during the
* verification process.
*/
int mbedtls_x509_crt_verify( mbedtls_x509_crt *crt,
mbedtls_x509_crt *trust_ca,
mbedtls_x509_crl *ca_crl,
const char *cn, uint32_t *flags,
int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
void *p_vrfy );
/**
* \brief Verify the certificate signature according to profile
*
* \note Same as \c mbedtls_x509_crt_verify(), but with explicit
* security profile.
*
* \note The restrictions on keys (RSA minimum size, allowed curves
* for ECDSA) apply to all certificates: trusted root,
* intermediate CAs if any, and end entity certificate.
*
* \param crt a certificate (chain) to be verified
* \param trust_ca the list of trusted CAs
* \param ca_crl the list of CRLs for trusted CAs
* \param profile security profile for verification
* \param cn expected Common Name (can be set to
* NULL if the CN must not be verified)
* \param flags result of the verification
* \param f_vrfy verification function
* \param p_vrfy verification parameter
*
* \return 0 if successful or MBEDTLS_ERR_X509_CERT_VERIFY_FAILED
* in which case *flags will have one or more
* MBEDTLS_X509_BADCERT_XXX or MBEDTLS_X509_BADCRL_XXX flags
* set,
* or another error in case of a fatal error encountered
* during the verification process.
*/
int mbedtls_x509_crt_verify_with_profile( mbedtls_x509_crt *crt,
mbedtls_x509_crt *trust_ca,
mbedtls_x509_crl *ca_crl,
const mbedtls_x509_crt_profile *profile,
const char *cn, uint32_t *flags,
int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
void *p_vrfy );
#if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
/**
* \brief Check usage of certificate against keyUsage extension.
*
* \param crt Leaf certificate used.
* \param usage Intended usage(s) (eg MBEDTLS_X509_KU_KEY_ENCIPHERMENT
* before using the certificate to perform an RSA key
* exchange).
*
* \note Except for decipherOnly and encipherOnly, a bit set in the
* usage argument means this bit MUST be set in the
* certificate. For decipherOnly and encipherOnly, it means
* that bit MAY be set.
*
* \return 0 is these uses of the certificate are allowed,
* MBEDTLS_ERR_X509_BAD_INPUT_DATA if the keyUsage extension
* is present but does not match the usage argument.
*
* \note You should only call this function on leaf certificates, on
* (intermediate) CAs the keyUsage extension is automatically
* checked by \c mbedtls_x509_crt_verify().
*/
int mbedtls_x509_crt_check_key_usage( const mbedtls_x509_crt *crt,
unsigned int usage );
#endif /* MBEDTLS_X509_CHECK_KEY_USAGE) */
#if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
/**
* \brief Check usage of certificate against extendedKeyUsage.
*
* \param crt Leaf certificate used.
* \param usage_oid Intended usage (eg MBEDTLS_OID_SERVER_AUTH or
* MBEDTLS_OID_CLIENT_AUTH).
* \param usage_len Length of usage_oid (eg given by MBEDTLS_OID_SIZE()).
*
* \return 0 if this use of the certificate is allowed,
* MBEDTLS_ERR_X509_BAD_INPUT_DATA if not.
*
* \note Usually only makes sense on leaf certificates.
*/
int mbedtls_x509_crt_check_extended_key_usage( const mbedtls_x509_crt *crt,
const char *usage_oid,
size_t usage_len );
#endif /* MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE */
#if defined(MBEDTLS_X509_CRL_PARSE_C)
/**
* \brief Verify the certificate revocation status
*
* \param crt a certificate to be verified
* \param crl the CRL to verify against
*
* \return 1 if the certificate is revoked, 0 otherwise
*
*/
int mbedtls_x509_crt_is_revoked( const mbedtls_x509_crt *crt, const mbedtls_x509_crl *crl );
#endif /* MBEDTLS_X509_CRL_PARSE_C */
/**
* \brief Initialize a certificate (chain)
*
* \param crt Certificate chain to initialize
*/
void mbedtls_x509_crt_init( mbedtls_x509_crt *crt );
/**
* \brief Unallocate all certificate data
*
* \param crt Certificate chain to free
*/
void mbedtls_x509_crt_free( mbedtls_x509_crt *crt );
#endif /* MBEDTLS_X509_CRT_PARSE_C */
/* \} name */
/* \} addtogroup x509_module */
#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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
/**
* \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 );
#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 );
/**
* \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 );
#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 );
/**
* \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 );
/**
* \brief Free the contents of a CRT write context
*
* \param ctx CRT context to free
*/
void mbedtls_x509write_crt_free( mbedtls_x509write_cert *ctx );
/**
* \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 );
#if defined(MBEDTLS_PEM_WRITE_C)
/**
* \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 *ctx, unsigned char *buf, size_t size,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng );
#endif /* MBEDTLS_PEM_WRITE_C */
#endif /* MBEDTLS_X509_CRT_WRITE_C */
#ifdef __cplusplus
}
#endif
#endif /* mbedtls_x509_crt.h */