MAN page from Trustix openssl-0.9.7m-1tr.i586.rpm
Section: OpenSSL (1)
ocsp - Online Certificate Status Protocol utility
The Online Certificate Status Protocol (OCSP
) enables applications todetermine the (revocation) state of an identified certificate (RFC
The ocsp command performs many common OCSP tasks. It can be usedto print out requests and responses, create requests and send queriesto 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 usedmultiple times. The certificate specified in filename must be inPEM format.
- -cert filename
- Add the certificate filename to the request. The issuer certificateis taken from the previous issuer option, or an error occurs if noissuer certificate is specified.
- -serial num
- Same as the cert option except the certificate with serial numbernum is added to the request. The serial number is interpreted as adecimal integer unless preceded by 0x. Negative integers can alsobe specified by preceding the value by a - sign.
- -signer filename, -signkey filename
- Sign the OCSP request using the certificate specified in the signeroption and the private key specified by the signkey option. Ifthe signkey option is not present then the private key is readfrom the same file as the certificate. If neither option is specified thenthe 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 nononce 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 ignoredif OCSP request or response creation is implied by other options (for examplewith 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 hosthostname on port port. path specifies the HTTP path name to useor ``/'' by default.
- -CAfile file, -CApath pathname
- file or pathname containing trusted CA certificates. These are used to verifythe signature on the OCSP response.
- -verify_other file
- file containing additional certificates to search when attempting to locatethe OCSP response signing certificate. Some responders omit the actual signer'scertificate from the response: this option can be used to supply the necessarycertificate in such cases.
- the certificates specified by the -verify_certs option should be explicitlytrusted and no additional checks will be performed on them. This is usefulwhen the complete responder certificate chain is not available or trusting aroot CA is not appropriate.
- -VAfile file
- file containing explicitly trusted responder certificates. Equivalent to the-verify_certs and -trust_other options.
- don't attempt to verify the OCSP response signature or the nonce values. Thisoption will normally only be used for debugging since it disables all verificationof the responders certificate.
- ignore certificates contained in the OCSP response when searching for thesigners certificate. With this option the signers certificate must be specifiedwith either the -verify_certs or -VAfile options.
- don't check the signature on the OCSP response. Since this option tolerates invalidsignatures on OCSP responses it will normally only be used for testing purposes.
- don't verify the OCSP response signers certificate at all. Since this option allowsthe OCSP response to be signed by any certificate it should only be used fortesting purposes.
- do not use certificates in the response as additional untrusted CAcertificates.
- 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 authorisedto provide the necessary status information: as a result this option shouldonly be used for testing purposes.
- -validity_period nsec, -status_age age
- these options specify the range of times, in seconds, which will be toleratedin an OCSP response. Each certificate status response includes a notBefore time andan optional notAfter time. The current time should fall between these two values, butthe interval between the two times may be only a few seconds. In practice the OCSPresponder and clients clocks may not be precisely synchronised and so such a checkmay fail. To avoid this the -validity_period option can be used to specify anacceptable error range in seconds, the default value is 5 minutes.
If the notAfter time is omitted from a response then this means that new statusinformation is immediately available. In this case the age of the notBefore fieldis checked to see it is not older than age seconds old. By default this additionalcheck is not performed.
OCSP SERVER OPTIONS
- -index indexfile
- indexfile is a text index file in ca format containing certificate revocationinformation.
If the index option is specified the ocsp utility is in responder mode, otherwiseit is in client mode. The request(s) the responder processes can be either specified onthe command line (using issuer and serial options), supplied in a file (using therespin 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 bepresent.
- -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.
- Don't include any certificates in the OCSP response.
- 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 thersigner option is used.
- -port portnum
- Port to listen for OCSP requests on. The port may also be specified using the urloption.
- -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 thenextUpdate field. If neither option is present then the nextUpdate field is omitted meaning fresh revocation information is immediately available.
OCSP Response verification.OCSP
Response follows the rules specified in RFC2560
Initially the OCSP responder certificate is located and the signature onthe OCSP request checked using the responder certificate's public key.
Then a normal certificate verify is performed on the OCSP responder certificatebuilding up a certificate chain in the process. The locations of the trustedcertificates used to build the chain can be specified by the CAfileand CApath options or they will be looked for in the standard OpenSSLcertificates directory.
If the initial verify fails then the OCSP verify process halts with anerror.
Otherwise the issuing CA certificate in the request is compared to the OCSPresponder certificate: if there is a match then the OCSP verify succeeds.
Otherwise the OCSP responder certificate's CA is checked against the issuingCA certificate in the request. If there is a match and the OCSPSigningextended key usage is present in the OCSP responder certificate then theOCSP verify succeeds.
Otherwise the root CA of the OCSP responders CA is checked to see if itis 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 isauthorised 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 aboutmultiple CAs and has its own separate certificate chain then its rootCA can be trusted for OCSP signing. For example:
openssl x509 -in ocspCA.pem -addtrust OCSPSigning -out trustedCA.pem
Alternatively the responder certificate itself can be explicitly trustedwith the -VAfile option.
As noted, most of the verify options are for testing or debugging purposes.Normally only the -CApath
and (if the responder is a 'globalVA
options need to be used.
The OCSP server is only useful for test and demonstration purposes: it isnot really usable as a full OCSP responder. It contains only a verysimple HTTP request handling and can only handle the POST form of OCSPqueries. It also handles requests serially meaning it cannot respond tonew requests until it has processed the current one. The text index fileformat of revocation is also inefficient for large quantities of revocationdata.
It is possible to run the ocsp application in responder mode via a CGIscript using the respin and respout options.
Create an OCSP
request and write it to a file:
openssl ocsp -issuer issuer.pem -cert c1.pem -cert c2.pem -reqout req.der
Send a query to an OCSP responder with URL http://ocsp.myhost.com/ save the response to a file and print it out in text form
openssl ocsp -issuer issuer.pem -cert c1.pem -cert c2.pem \ -url http://ocsp.myhost.com/ -resp_text -respout resp.der
Read in an OCSP response and print out text form:
openssl ocsp -respin resp.der -text
OCSP server on port 8888 using a standard ca configuration, and a separateresponder certificate. All requests and responses are printed to a file.
openssl ocsp -index demoCA/index.txt -port 8888 -rsigner rcert.pem -CA demoCA/cacert.pem -text -out log.txt
As above but exit after processing one request:
openssl ocsp -index demoCA/index.txt -port 8888 -rsigner rcert.pem -CA demoCA/cacert.pem -nrequest 1
Query status information using internally generated request:
openssl ocsp -index demoCA/index.txt -rsigner rcert.pem -CA demoCA/cacert.pem -issuer demoCA/cacert.pem -serial 1
Query status information using request read from a file, write response to asecond file.
openssl ocsp -index demoCA/index.txt -rsigner rcert.pem -CA demoCA/cacert.pem -reqin req.der -respout resp.der
- OCSP CLIENT OPTIONS
- OCSP SERVER OPTIONS
- OCSP Response verification.
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