NAME
    ocsp - Online Certificate Status Protocol utility

SYNOPSIS
    openssl ocsp [-out file] [-issuer file] [-cert file] [-serial n]
    [-req_text] [-resp_text] [-text] [-reqout file] [-respout file] [-reqin
    file] [-respin file] [-nonce] [-no_nonce] [-url responder_url] [-host
    host:n] [-path] [-CApath file] [-CAfile file] [-VAfile file] [-ver-
    ify_certs file] [-noverify] [-trust_other] [-no_intern] [-no_sig_ver-
    ify] [-no_cert_verify] [-no_chain] [-no_cert_checks] [-validity_period
    nsec] [-status_age nsec]

DESCRIPTION
    WARNING: this documentation is preliminary and subject to change.

    The 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.

    -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 addi-
   tion 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_certs 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. Equiva-
   lent 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 certifi-
   cate must be specified with either the -verify_certs or -VAfile
   options.

    -no_sig_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 certifi-
   cate 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 test-
   ing 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 cur-
   rent 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 per-
   formed.

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 revoca-
   tion 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
    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 loca-
    tions of the trusted certificates used to build the chain can be speci-
    fied 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 cer-
    tificate 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

    Alternatively the responder certificate itself can be explicitly
    trusted with the -VAfile option.

NOTES
    As noted, most of the verify options are for testing or debugging pur-
    poses. 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.

EXAMPLES
    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 sepa-
    rate 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