DESCRIPTIONThe Online Certificate Status Protocol (OCSP) enables applications
to determine the (revocation) state of an identified certificate
(RFC 2560).
The ocsp command performs many common OCSP tasks. It can be
used to print out requests and responses, create requests and send
queries to an OCSP responder and behave like a mini OCSP server
itself.
OCSP CLIENT OPTIONS
-out filename specify output filename, default is standard output.
-issuer filename This specifies the current issuer certificate. This option
can be used multiple times. The certificate specified in filename
must be in PEM format.
-cert filename Add the certificate filename to the request. The issuer certificate
is taken from the previous issuer option, or an error occurs if
no issuer certificate is specified.
-serial num Same as the cert option except the certificate with serial
number num is added to the request. The serial number is interpreted
as a decimal integer unless preceded by 0x. Negative integers can
also be specified by preceding the value by a - sign.
-signer filename, -signkey filename Sign the OCSP request using the certificate specified in the
signer option and the private key specified by the signkey option.
If the signkey option is not present then the private key is read
from the same file as the certificate. If neither option is specified
then the OCSP request is not signed.
-sign_other filename Additional certificates to include in the signed request.
-nonce, -no_nonce Add an OCSP nonce extension to a request or disable OCSP nonce
addition. Normally if an OCSP request is input using the respin
option no nonce is added: using the nonce option will force addition
of a nonce. If an OCSP request is being created (using cert and
serial options) a nonce is automatically added specifying no_nonce
overrides this.
-req_text, -resp_text, -text print out the text form of the OCSP request, response or both
respectively.
-reqout file, -respout file write out the DER encoded certificate request or response
to file.
-reqin file, respin file read OCSP request or response file from file . These option
are ignored if OCSP request or response creation is implied by other
options (for example with serial , cert and host options).
-url responder_url specify the responder URL. Both HTTP and HTTPS (SSL/TLS) URLs
can be specified.
-host hostname:port, -path pathname if the host option is present then the OCSP request is sent
to the host hostname on port port. path specifies the HTTP path
name to use or "/" by default.
-CAfile file, -CApath pathname file or pathname containing trusted CA certificates. These
are used to verify the signature on the OCSP response.
-verify_other file file containing additional certificates to search when attempting
to locate the OCSP response signing certificate. Some responders
omit the actual signer's certificate from the response: this option
can be used to supply the necessary certificate in such cases.
-trust_other the certificates specified by the -verify_certs option should
be explicitly trusted and no additional checks will be performed
on them. This is useful when the complete responder certificate
chain is not available or trusting a root CA is not appropriate.
-VAfile file file containing explicitly trusted responder certificates.
Equivalent to the -verify_certs and -trust_other options.
-noverify don't attempt to verify the OCSP response signature or the
nonce values. This option will normally only be used for debugging
since it disables all verification of the responders certificate.
-no_intern ignore certificates contained in the OCSP response when searching
for the signers certificate. With this option the signers certificate
must be specified with either the -verify_certs or -VAfile options.
-no_signature_verify don't check the signature on the OCSP response. Since this
option tolerates invalid signatures on OCSP responses it will normally
only be used for testing purposes.
-no_cert_verify don't verify the OCSP response signers certificate at all.
Since this option allows the OCSP response to be signed by any certificate
it should only be used for testing purposes.
-no_chain do not use certificates in the response as additional untrusted
CA certificates.
-no_cert_checks don't perform any additional checks on the OCSP response signers
certificate. That is do not make any checks to see if the signers
certificate is authorised to provide the necessary status information:
as a result this option should only be used for testing purposes.
-validity_period nsec, -status_age age these options specify the range of times, in seconds, which
will be tolerated in an OCSP response. Each certificate status response
includes a notBefore time and an optional notAfter time. The current
time should fall between these two values, but the interval between
the two times may be only a few seconds. In practice the OCSP responder
and clients clocks may not be precisely synchronised and so such
a check may fail. To avoid this the -validity_period option can
be used to specify an acceptable error range in seconds, the default
value is 5 minutes. If the notAfter time is omitted from a response then this
means that new status information is immediately available. In this
case the age of the notBefore field is checked to see it is not
older than age seconds old. By default this additional check is
not performed.
OCSP SERVER OPTIONS
-index indexfile indexfile is a text index file in ca format containing certificate
revocation information. If the index option is specified the ocsp utility is in responder
mode, otherwise it is in client mode. The request(s) the responder
processes can be either specified on the command line (using issuer
and serial options), supplied in a file (using the respin option)
or via external OCSP clients (if port or url is specified.) If the index option is present then the CA and rsigner options
must also be present.
-CA file CA certificate corresponding to the revocation information
in indexfile.
-rsigner file The certificate to sign OCSP responses with.
-rother file Additional certificates to include in the OCSP response.
-resp_no_certs Don't include any certificates in the OCSP response.
-resp_key_id Identify the signer certificate using the key ID, default
is to use the subject name.
-rkey file The private key to sign OCSP responses with: if not present
the file specified in the rsigner option is used.
-port portnum Port to listen for OCSP requests on. The port may also be
specified using the url option.
-nrequest number The OCSP server will exit after receiving number requests,
default unlimited.
-nmin minutes, -ndays days Number of minutes or days when fresh revocation information
is available: used in the nextUpdate field. If neither option is
present then the nextUpdate field is omitted meaning fresh revocation
information is immediately available.
OCSP Response VerificationOCSP Response follows the rules specified in RFC2560.
Initially the OCSP responder certificate is located and the
signature on the OCSP request checked using the responder certificate's
public key.
Then a normal certificate verify is performed on the OCSP
responder certificate building up a certificate chain in the process.
The locations of the trusted certificates used to build the chain
can be specified by the CAfile and CApath options or they will be
looked for in the standard OpenSSL certificates directory.
If the initial verify fails then the OCSP verify process halts
with an error.
Otherwise the issuing CA certificate in the request is compared
to the OCSP responder certificate: if there is a match then the
OCSP verify succeeds.
Otherwise the OCSP responder certificate's CA is checked against
the issuing CA certificate in the request. If there is a match and
the OCSPSigning extended key usage is present in the OCSP responder
certificate then the OCSP verify succeeds.
Otherwise the root CA of the OCSP responders CA is checked
to see if it is trusted for OCSP signing. If it is the OCSP verify
succeeds.
If none of these checks is successful then the OCSP verify
fails.
What this effectively means if that if the OCSP responder
certificate is authorised directly by the CA it is issuing revocation
information about (and it is correctly configured) then verification
will succeed.
If the OCSP responder is a "global responder" which can give
details about multiple CAs and has its own separate certificate
chain then its root CA can be trusted for OCSP signing. For example:
Alternatively the responder certificate itself can be explicitly
trusted with the -VAfile option. NOTESAs noted, most of the verify options are for testing or debugging
purposes. Normally only the -CApath, -CAfile and (if the responder
is a 'global VA') -VAfile options need to be used.
The OCSP server is only useful for test and demonstration
purposes: it is not really usable as a full OCSP responder. It contains
only a very simple HTTP request handling and can only handle the
POST form of OCSP queries. It also handles requests serially meaning
it cannot respond to new requests until it has processed the current
one. The text index file format of revocation is also inefficient
for large quantities of revocation data.
It is possible to run the ocsp application in responder mode
via a CGI script using the respin and respout options.
EXAMPLESCreate an OCSP request and write it to a file:
HP Open Source Security for OpenVMS Volume 2:... 
OpenSSL Command Line Interface (CLI) Reference
