Willie Solano
mbed TLS Build
Diff: include/mbedtls/x509_crt.h
- Revision:
- 0:cdf462088d13
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/include/mbedtls/x509_crt.h Thu Jan 05 00:18:44 2017 +0000
@@ -0,0 +1,654 @@
+/**
+ * \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 but a fatal error.
+ *
+ * \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.
+ *
+ * \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 (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 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( 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 extentedJeyUsage.
+ *
+ * \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 */
