OCSP API (GnuTLS 3.8.4)

E.5 OCSP API

The following functions are for OCSP certificate status checking. Their prototypes lie in gnutls/ocsp.h.

gnutls_ocsp_req_add_cert

Function: int gnutls_ocsp_req_add_cert (gnutls_ocsp_req_t req, gnutls_digest_algorithm_t digest, gnutls_x509_crt_t issuer, gnutls_x509_crt_t cert)

req: should contain a gnutls_ocsp_req_t type

digest: hash algorithm, a gnutls_digest_algorithm_t value

issuer: issuer of subject certificate

cert: certificate to request status for

This function will add another request to the OCSP request for a particular certificate. The issuer name hash, issuer key hash, and serial number fields is populated as follows. The issuer name and the serial number is taken from cert . The issuer key is taken from issuer . The hashed values will be hashed using the digest algorithm, normally GNUTLS_DIG_SHA1 .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_add_cert_id

Function: int gnutls_ocsp_req_add_cert_id (gnutls_ocsp_req_t req, gnutls_digest_algorithm_t digest, const gnutls_datum_t * issuer_name_hash, const gnutls_datum_t * issuer_key_hash, const gnutls_datum_t * serial_number)

req: should contain a gnutls_ocsp_req_t type

digest: hash algorithm, a gnutls_digest_algorithm_t value

issuer_name_hash: hash of issuer’s DN

issuer_key_hash: hash of issuer’s public key

serial_number: serial number of certificate to check

This function will add another request to the OCSP request for a particular certificate having the issuer name hash of issuer_name_hash and issuer key hash of issuer_key_hash (both hashed using digest ) and serial number serial_number .

The information needed corresponds to the CertID structure:

<informalexample><programlisting> CertID ::= SEQUENCE { hashAlgorithm AlgorithmIdentifier, issuerNameHash OCTET STRING, – Hash of Issuer’s DN issuerKeyHash OCTET STRING, – Hash of Issuers public key serialNumber CertificateSerialNumber } </programlisting></informalexample>

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_deinit

Function: void gnutls_ocsp_req_deinit (gnutls_ocsp_req_t req)

req: The data to be deinitialized

This function will deinitialize a OCSP request structure.

gnutls_ocsp_req_export

Function: int gnutls_ocsp_req_export (gnutls_ocsp_req_const_t req, gnutls_datum_t * data)

req: Holds the OCSP request

data: newly allocate buffer holding DER encoded OCSP request

This function will export the OCSP request to DER format.

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_ocsp_req_get_cert_id

Function: int gnutls_ocsp_req_get_cert_id (gnutls_ocsp_req_const_t req, unsigned indx, gnutls_digest_algorithm_t * digest, gnutls_datum_t * issuer_name_hash, gnutls_datum_t * issuer_key_hash, gnutls_datum_t * serial_number)

req: should contain a gnutls_ocsp_req_t type

indx: Specifies which extension OID to get. Use (0) to get the first one.

digest: output variable with gnutls_digest_algorithm_t hash algorithm

issuer_name_hash: output buffer with hash of issuer’s DN

issuer_key_hash: output buffer with hash of issuer’s public key

serial_number: output buffer with serial number of certificate to check

This function will return the certificate information of the indx ’ed request in the OCSP request. The information returned corresponds to the CertID structure:

Each of the pointers to output variables may be NULL to indicate that the caller is not interested in that value.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last CertID available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_ocsp_req_get_extension

Function: int gnutls_ocsp_req_get_extension (gnutls_ocsp_req_const_t req, unsigned indx, gnutls_datum_t * oid, unsigned int * critical, gnutls_datum_t * data)

req: should contain a gnutls_ocsp_req_t type

indx: Specifies which extension OID to get. Use (0) to get the first one.

oid: will hold newly allocated buffer with OID of extension, may be NULL

critical: output variable with critical flag, may be NULL.

data: will hold newly allocated buffer with extension data, may be NULL

This function will return all information about the requested extension in the OCSP request. The information returned is the OID, the critical flag, and the data itself. The extension OID will be stored as a string. Any of oid , critical , and data may be NULL which means that the caller is not interested in getting that information back.

The caller needs to deallocate memory by calling gnutls_free() on oid ->data and data ->data.

Since 3.7.0 oid ->size does not account for the terminating null byte.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. If you have reached the last extension available GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

gnutls_ocsp_req_get_nonce

Function: int gnutls_ocsp_req_get_nonce (gnutls_ocsp_req_const_t req, unsigned int * critical, gnutls_datum_t * nonce)

req: should contain a gnutls_ocsp_req_t type

critical: whether nonce extension is marked critical, or NULL

nonce: will hold newly allocated buffer with nonce data

This function will return the OCSP request nonce extension data.

The caller needs to deallocate memory by calling gnutls_free() on nonce ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_get_version

Function: int gnutls_ocsp_req_get_version (gnutls_ocsp_req_const_t req)

req: should contain a gnutls_ocsp_req_t type

This function will return the version of the OCSP request. Typically this is always 1 indicating version 1.

Returns: version of OCSP request, or a negative error code on error.

gnutls_ocsp_req_import

Function: int gnutls_ocsp_req_import (gnutls_ocsp_req_t req, const gnutls_datum_t * data)

req: The data to store the parsed request.

data: DER encoded OCSP request.

This function will convert the given DER encoded OCSP request to the native gnutls_ocsp_req_t format. The output will be stored in req .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_req_init

Function: int gnutls_ocsp_req_init (gnutls_ocsp_req_t * req)

req: A pointer to the type to be initialized

This function will initialize an OCSP request structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_req_print

Function: int gnutls_ocsp_req_print (gnutls_ocsp_req_const_t req, gnutls_ocsp_print_formats_t format, gnutls_datum_t * out)

req: The data to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a OCSP request, suitable for display to a human.

If the format is GNUTLS_OCSP_PRINT_FULL then all fields of the request will be output, on multiple lines.

The output out ->data needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_req_randomize_nonce

Function: int gnutls_ocsp_req_randomize_nonce (gnutls_ocsp_req_t req)

req: should contain a gnutls_ocsp_req_t type

This function will add or update an nonce extension to the OCSP request with a newly generated random value.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_set_extension

Function: int gnutls_ocsp_req_set_extension (gnutls_ocsp_req_t req, const char * oid, unsigned int critical, const gnutls_datum_t * data)

req: should contain a gnutls_ocsp_req_t type

oid: buffer with OID of extension as a string.

critical: critical flag, normally false.

data: the extension data

This function will add an extension to the OCSP request. Calling this function multiple times for the same OID will overwrite values from earlier calls.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_req_set_nonce

Function: int gnutls_ocsp_req_set_nonce (gnutls_ocsp_req_t req, unsigned int critical, const gnutls_datum_t * nonce)

req: should contain a gnutls_ocsp_req_t type

critical: critical flag, normally false.

nonce: the nonce data

This function will add an nonce extension to the OCSP request. Calling this function multiple times will overwrite values from earlier calls.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_resp_check_crt

Function: int gnutls_ocsp_resp_check_crt (gnutls_ocsp_resp_const_t resp, unsigned int indx, gnutls_x509_crt_t crt)

resp: should contain a gnutls_ocsp_resp_t type

indx: Specifies response number to get. Use (0) to get the first one.

crt: The certificate to check

This function will check whether the OCSP response is about the provided certificate.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

Since: 3.1.3

gnutls_ocsp_resp_deinit

Function: void gnutls_ocsp_resp_deinit (gnutls_ocsp_resp_t resp)

resp: The data to be deinitialized

This function will deinitialize a OCSP response structure.

gnutls_ocsp_resp_export

Function: int gnutls_ocsp_resp_export (gnutls_ocsp_resp_const_t resp, gnutls_datum_t * data)

resp: Holds the OCSP response

data: newly allocate buffer holding DER encoded OCSP response

This function will export the OCSP response to DER format.

Returns: In case of failure a negative error code will be returned, and 0 on success.

gnutls_ocsp_resp_export2

Function: int gnutls_ocsp_resp_export2 (gnutls_ocsp_resp_const_t resp, gnutls_datum_t * data, gnutls_x509_crt_fmt_t fmt)

resp: Holds the OCSP response

data: newly allocate buffer holding DER or PEM encoded OCSP response

fmt: DER or PEM

This function will export the OCSP response to DER or PEM format.

Returns: In case of failure a negative error code will be returned, and 0 on success.

Since: 3.6.3

gnutls_ocsp_resp_get_certs

Function: int gnutls_ocsp_resp_get_certs (gnutls_ocsp_resp_const_t resp, gnutls_x509_crt_t ** certs, size_t * ncerts)

resp: should contain a gnutls_ocsp_resp_t type

certs: newly allocated array with gnutls_x509_crt_t certificates

ncerts: output variable with number of allocated certs.

This function will extract the X.509 certificates found in the Basic OCSP Response. The certs output variable will hold a newly allocated zero-terminated array with X.509 certificates.

Every certificate in the array needs to be de-allocated with gnutls_x509_crt_deinit() and the array itself must be freed using gnutls_free() .

Both the certs and ncerts variables may be NULL. Then the function will work as normal but will not return the NULL:d information. This can be used to get the number of certificates only, or to just get the certificate array without its size.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_get_extension

Function: int gnutls_ocsp_resp_get_extension (gnutls_ocsp_resp_const_t resp, unsigned indx, gnutls_datum_t * oid, unsigned int * critical, gnutls_datum_t * data)

resp: should contain a gnutls_ocsp_resp_t type

indx: Specifies which extension OID to get. Use (0) to get the first one.

oid: will hold newly allocated buffer with OID of extension, may be NULL

critical: output variable with critical flag, may be NULL.

data: will hold newly allocated buffer with extension data, may be NULL

This function will return all information about the requested extension in the OCSP response. The information returned is the OID, the critical flag, and the data itself. The extension OID will be stored as a string. Any of oid , critical , and data may be NULL which means that the caller is not interested in getting that information back.

The caller needs to deallocate memory by calling gnutls_free() on oid ->data and data ->data.

Since 3.7.0 oid ->size does not account for the terminating null byte.

gnutls_ocsp_resp_get_nonce

Function: int gnutls_ocsp_resp_get_nonce (gnutls_ocsp_resp_const_t resp, unsigned int * critical, gnutls_datum_t * nonce)

resp: should contain a gnutls_ocsp_resp_t type

critical: whether nonce extension is marked critical

nonce: will hold newly allocated buffer with nonce data

This function will return the Basic OCSP Response nonce extension data.

The caller needs to deallocate memory by calling gnutls_free() on nonce ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_resp_get_produced

Function: time_t gnutls_ocsp_resp_get_produced (gnutls_ocsp_resp_const_t resp)

resp: should contain a gnutls_ocsp_resp_t type

This function will return the time when the OCSP response was signed.

Returns: signing time, or (time_t)-1 on error.

gnutls_ocsp_resp_get_responder

Function: int gnutls_ocsp_resp_get_responder (gnutls_ocsp_resp_const_t resp, gnutls_datum_t * dn)

resp: should contain a gnutls_ocsp_resp_t type

dn: newly allocated buffer with name

This function will extract the name of the Basic OCSP Response in the provided buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as described in RFC2253. The output string will be ASCII or UTF-8 encoded, depending on the certificate data.

If the responder ID is not a name but a hash, this function will return zero and the dn elements will be set to NULL .

The caller needs to deallocate memory by calling gnutls_free() on dn ->data.

This function does not output a fully RFC4514 compliant string, if that is required see gnutls_ocsp_resp_get_responder2() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. When no data exist it will return success and set dn elements to zero.

gnutls_ocsp_resp_get_responder2

Function: int gnutls_ocsp_resp_get_responder2 (gnutls_ocsp_resp_const_t resp, gnutls_datum_t * dn, unsigned flags)

resp: should contain a gnutls_ocsp_resp_t type

dn: newly allocated buffer with name

flags: zero or GNUTLS_X509_DN_FLAG_COMPAT

If the responder ID is not a name but a hash, this function will return zero and the dn elements will be set to NULL .

The caller needs to deallocate memory by calling gnutls_free() on dn ->data.

When the flag GNUTLS_X509_DN_FLAG_COMPAT is specified, the output format will match the format output by previous to 3.5.6 versions of GnuTLS which was not not fully RFC4514-compliant.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned. When no data exist it will return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE .

gnutls_ocsp_resp_get_responder_raw_id

Function: int gnutls_ocsp_resp_get_responder_raw_id (gnutls_ocsp_resp_const_t resp, unsigned type, gnutls_datum_t * raw)

resp: should contain a gnutls_ocsp_resp_t type

type: should be GNUTLS_OCSP_RESP_ID_KEY or GNUTLS_OCSP_RESP_ID_DN

raw: newly allocated buffer with the raw ID

This function will extract the raw key (or DN) ID of the Basic OCSP Response in the provided buffer. If the responder ID is not a key ID then this function will return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE .

The caller needs to deallocate memory by calling gnutls_free() on dn ->data.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error code is returned.

gnutls_ocsp_resp_get_response

Function: int gnutls_ocsp_resp_get_response (gnutls_ocsp_resp_const_t resp, gnutls_datum_t * response_type_oid, gnutls_datum_t * response)

resp: should contain a gnutls_ocsp_resp_t type

response_type_oid: newly allocated output buffer with response type OID

response: newly allocated output buffer with DER encoded response

This function will extract the response type OID in and the response data from an OCSP response. Normally the response_type_oid is always "1.3.6.1.5.5.7.48.1.1" which means the response should be decoded as a Basic OCSP Response, but technically other response types could be used.

This function is typically only useful when you want to extract the response type OID of an response for diagnostic purposes. Otherwise gnutls_ocsp_resp_import() will decode the basic OCSP response part and the caller need not worry about that aspect.

Since 3.7.0 response_type_oid ->size does not account for the terminating null byte.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_get_signature

Function: int gnutls_ocsp_resp_get_signature (gnutls_ocsp_resp_const_t resp, gnutls_datum_t * sig)

resp: should contain a gnutls_ocsp_resp_t type

sig: newly allocated output buffer with signature data

This function will extract the signature field of a OCSP response.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_get_signature_algorithm

Function: int gnutls_ocsp_resp_get_signature_algorithm (gnutls_ocsp_resp_const_t resp)

resp: should contain a gnutls_ocsp_resp_t type

This function will return a value of the gnutls_sign_algorithm_t enumeration that is the signature algorithm that has been used to sign the OCSP response.

Returns: a gnutls_sign_algorithm_t value, or a negative error code on error.

gnutls_ocsp_resp_get_single

Function: int gnutls_ocsp_resp_get_single (gnutls_ocsp_resp_const_t resp, unsigned indx, gnutls_digest_algorithm_t * digest, gnutls_datum_t * issuer_name_hash, gnutls_datum_t * issuer_key_hash, gnutls_datum_t * serial_number, unsigned int * cert_status, time_t * this_update, time_t * next_update, time_t * revocation_time, unsigned int * revocation_reason)

resp: should contain a gnutls_ocsp_resp_t type

indx: Specifies response number to get. Use (0) to get the first one.

digest: output variable with gnutls_digest_algorithm_t hash algorithm

issuer_name_hash: output buffer with hash of issuer’s DN

issuer_key_hash: output buffer with hash of issuer’s public key

serial_number: output buffer with serial number of certificate to check

cert_status: a certificate status, a gnutls_ocsp_cert_status_t enum.

this_update: time at which the status is known to be correct.

next_update: when newer information will be available, or (time_t)-1 if unspecified

revocation_time: when cert_status is GNUTLS_OCSP_CERT_REVOKED , holds time of revocation.

revocation_reason: revocation reason, a gnutls_x509_crl_reason_t enum.

This function will return the certificate information of the indx ’ed response in the Basic OCSP Response resp . The information returned corresponds to the OCSP SingleResponse structure except the final singleExtensions.

Each of the pointers to output variables may be NULL to indicate that the caller is not interested in that value.

gnutls_ocsp_resp_get_status

Function: int gnutls_ocsp_resp_get_status (gnutls_ocsp_resp_const_t resp)

resp: should contain a gnutls_ocsp_resp_t type

This function will return the status of a OCSP response, an gnutls_ocsp_resp_status_t enumeration.

Returns: status of OCSP request as a gnutls_ocsp_resp_status_t , or a negative error code on error.

gnutls_ocsp_resp_get_version

Function: int gnutls_ocsp_resp_get_version (gnutls_ocsp_resp_const_t resp)

resp: should contain a gnutls_ocsp_resp_t type

This function will return the version of the Basic OCSP Response. Typically this is always 1 indicating version 1.

Returns: version of Basic OCSP response, or a negative error code on error.

gnutls_ocsp_resp_import

Function: int gnutls_ocsp_resp_import (gnutls_ocsp_resp_t resp, const gnutls_datum_t * data)

resp: The data to store the parsed response.

data: DER encoded OCSP response.

This function will convert the given DER encoded OCSP response to the native gnutls_ocsp_resp_t format. It also decodes the Basic OCSP Response part, if any. The output will be stored in resp .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_import2

Function: int gnutls_ocsp_resp_import2 (gnutls_ocsp_resp_t resp, const gnutls_datum_t * data, gnutls_x509_crt_fmt_t fmt)

resp: The data to store the parsed response.

data: DER or PEM encoded OCSP response.

fmt: DER or PEM

This function will convert the given OCSP response to the native gnutls_ocsp_resp_t format. It also decodes the Basic OCSP Response part, if any. The output will be stored in resp .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

Since: 3.6.3

gnutls_ocsp_resp_init

Function: int gnutls_ocsp_resp_init (gnutls_ocsp_resp_t * resp)

resp: A pointer to the type to be initialized

This function will initialize an OCSP response structure.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_list_import2

Function: int gnutls_ocsp_resp_list_import2 (gnutls_ocsp_resp_t ** ocsps, unsigned int * size, const gnutls_datum_t * resp_data, gnutls_x509_crt_fmt_t format, unsigned int flags)

ocsps: Will hold the parsed OCSP response list.

size: It will contain the size of the list.

resp_data: The PEM encoded OCSP list.

format: One of GNUTLS_X509_FMT_PEM or GNUTLS_X509_FMT_DER

flags: must be (0) or an OR’d sequence of gnutls_certificate_import_flags.

This function will convert the given PEM encoded OCSP response list to the native gnutls_ocsp_resp_t format. The output will be stored in ocsps which will be allocated and initialized.

The OCSP responses should have a header of "OCSP RESPONSE".

To deinitialize responses, you need to deinitialize each gnutls_ocsp_resp_t structure independently, and use gnutls_free() at ocsps .

In PEM files, when no OCSP responses are detected GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.

Returns: the number of responses read or a negative error value.

Since: 3.6.3

gnutls_ocsp_resp_print

Function: int gnutls_ocsp_resp_print (gnutls_ocsp_resp_const_t resp, gnutls_ocsp_print_formats_t format, gnutls_datum_t * out)

resp: The data to be printed

format: Indicate the format to use

out: Newly allocated datum with (0) terminated string.

This function will pretty print a OCSP response, suitable for display to a human.

If the format is GNUTLS_OCSP_PRINT_FULL then all fields of the response will be output, on multiple lines.

The output out ->data needs to be deallocate using gnutls_free() .

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_verify

Function: int gnutls_ocsp_resp_verify (gnutls_ocsp_resp_const_t resp, gnutls_x509_trust_list_t trustlist, unsigned int * verify, unsigned int flags)

resp: should contain a gnutls_ocsp_resp_t type

trustlist: trust anchors as a gnutls_x509_trust_list_t type

verify: output variable with verification status, an gnutls_ocsp_verify_reason_t

flags: verification flags from gnutls_certificate_verify_flags

Verify signature of the Basic OCSP Response against the public key in the certificate of a trusted signer. The trustlist should be populated with trust anchors. The function will extract the signer certificate from the Basic OCSP Response and will verify it against the trustlist . A trusted signer is a certificate that is either in trustlist , or it is signed directly by a certificate in trustlist and has the id-ad-ocspSigning Extended Key Usage bit set.

The output verify variable will hold verification status codes (e.g., GNUTLS_OCSP_VERIFY_SIGNER_NOT_FOUND , GNUTLS_OCSP_VERIFY_INSECURE_ALGORITHM ) which are only valid if the function returned GNUTLS_E_SUCCESS .

Note that the function returns GNUTLS_E_SUCCESS even when verification failed. The caller must always inspect the verify variable to find out the verification status.

The flags variable should be 0 for now.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.

gnutls_ocsp_resp_verify_direct

Function: int gnutls_ocsp_resp_verify_direct (gnutls_ocsp_resp_const_t resp, gnutls_x509_crt_t issuer, unsigned int * verify, unsigned int flags)

resp: should contain a gnutls_ocsp_resp_t type

issuer: certificate believed to have signed the response

verify: output variable with verification status, an gnutls_ocsp_verify_reason_t

flags: verification flags from gnutls_certificate_verify_flags

Verify signature of the Basic OCSP Response against the public key in the issuer certificate.

Note that the function returns GNUTLS_E_SUCCESS even when verification failed. The caller must always inspect the verify variable to find out the verification status.

The flags variable should be 0 for now.

Returns: On success, GNUTLS_E_SUCCESS (0) is returned, otherwise a negative error value.