ocsp - Online Certificate Status Protocol utility


   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] [-no_alt_chains]] [-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] [-no_explicit] [-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

   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.


   -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. This option MUST come before any -cert options.

   -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

   -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.

   -timeout seconds
       connection timeout to the OCSP responder in seconds

   -CAfile file, -CApath pathname
       file or pathname containing trusted CA certificates. These are used
       to verify the signature on the OCSP response.

       See verify manual page for details.

   -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.

       the certificates specified by the -verify_other 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_other and -trust_other options.

       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.

       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_other or
       -VAfile options.

       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.

       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.

       do not use certificates in the response as additional untrusted CA

       do not explicitly trust the root CA if it is set to be trusted for
       OCSP signing.

       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

       this option sets digest algorithm to use for certificate
       identification in the OCSP request. By default SHA-1 is used.


   -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

   -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 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

   -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 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

   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

   Otherwise the issuing CA certificate in the request is compared to the
   OCSP responder certificate: if there is a match then the OCSP verify

   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, if -no_explicit is not set 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.


   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.

   It is possible to run the ocsp application in responder mode via a CGI
   script 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
   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


   The -no_alt_chains options was first added to OpenSSL 1.0.2b.


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.

Free Software

Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.

Free Books

The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.