Section: OpenSSL (1SSL)
openssl ocsp [-out file] [-issuer file] [-cert file] [-serial n] [-signer file] [-signkey file] [-sign_other file] [-no_certs] [-req_text] [-resp_text] [-text] [-reqout file] [-respout file] [-reqin file] [-respin file] [-nonce] [-no_nonce] [-url URL] [-host host:n] [-path] [-CApath dir] [-CAfile file] [-VAfile file] [-validity_period n] [-status_age n] [-noverify] [-verify_other file] [-trust_other] [-no_intern] [-no_signature_verify] [-no_cert_verify] [-no_chain] [-no_cert_checks] [-port num] [-index file] [-CA file] [-rsigner file] [-rkey file] [-rother file] [-resp_no_certs] [-nmin n] [-ndays n] [-resp_key_id] [-nrequest n] [-md5|-sha1|...]
The Online Certificate Status Protocol (OCSP) enables applications to determine the (revocation) state of an identified certificate (RFC 2560).
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.
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.
OCSP 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:
openssl x509 -in ocspCA.pem -addtrust OCSPSigning -out trustedCA.pem
As 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.
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 separate responder 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 a second file.
openssl ocsp -index demoCA/index.txt -rsigner rcert.pem -CA demoCA/cacert.pem -reqin req.der -respout resp.der
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