Ubuntu Manpage: ocsptool - GnuTLS OCSP tool

Provided by: gnutls-bin_3.4.10-4ubuntu1.9_amd64

NAME

       ocsptool - GnuTLS OCSP tool

SYNOPSIS

       ocsptool [-flags] [-flag [value]] [--option-name[[=| ]value]]

       All arguments must be options.

DESCRIPTION

       Ocsptool  is a program that can parse and print information about OCSP requests/responses,
       generate requests and verify responses.

OPTIONS

-d number, --debug=number
Enable debugging. This option takes an integer number as its argument. The value
of number is constrained to being:
in the range 0 through 9999

Specifies the debug level.

-V, --verbose
More verbose output. This option may appear an unlimited number of times.

--infile=file
Input file.

--outfile=string
Output file.

--ask [=server name|url]
Ask an OCSP/HTTP server on a certificate validity. This option must appear in
combination with the following options: load-cert, load-issuer.

Connects to the specified HTTP OCSP server and queries on the validity of the
loaded certificate.

-e, --verify-response
Verify response.

-i, --request-info
Print information on a OCSP request.

-j, --response-info
Print information on a OCSP response.

-q, --generate-request
Generate an OCSP request.

--nonce, - Fl -no-nonce
Use (or not) a nonce to OCSP request. The no-nonce form will disable the option.

--load-issuer=file
Read issuer certificate from file.

--load-cert=file
Read certificate to check from file.

--load-trust=file
Read OCSP trust anchors from file. This option must not appear in combination with
any of the following options: load-signer.

--load-signer=file
Read OCSP response signer from file. This option must not appear in combination
with any of the following options: load-trust.

--inder, - Fl -no-inder
Use DER format for input certificates and private keys. The no-inder form will
disable the option.

-Q file, --load-request=file
Read DER encoded OCSP request from file.

-S file, --load-response=file
Read DER encoded OCSP response from file.

-h, --help
Display usage information and exit.

-!, --more-help
Pass the extended usage information through a pager.

-v [{v|c|n --version [{v|c|n}]}]
Output version of program and exit. The default mode is `v', a simple version.
The `c' mode will print copyright information and `n' will print the full copyright
notice.

EXAMPLES

Print information about an OCSP request

To parse an OCSP request and print information about the content, the -i or --request-info
parameter may be used as follows. The -Q parameter specify the name of the file
containing the OCSP request, and it should contain the OCSP request in binary DER format.

$ ocsptool -i -Q ocsp-request.der

The input file may also be sent to standard input like this:

$ cat ocsp-request.der | ocsptool --request-info

Print information about an OCSP response

Similar to parsing OCSP requests, OCSP responses can be parsed using the -j or
--response-info as follows.

$ ocsptool -j -Q ocsp-response.der
$ cat ocsp-response.der | ocsptool --response-info

Generate an OCSP request

The -q or --generate-request parameters are used to generate an OCSP request. By default
the OCSP request is written to standard output in binary DER format, but can be stored in
a file using --outfile. To generate an OCSP request the issuer of the certificate to
check needs to be specified with --load-issuer and the certificate to check with
--load-cert. By default PEM format is used for these files, although --inder can be used
to specify that the input files are in DER format.

$ ocsptool -q --load-issuer issuer.pem --load-cert client.pem --outfile ocsp-request.der

When generating OCSP requests, the tool will add an OCSP extension containing a nonce.
This behaviour can be disabled by specifying --no-nonce.

Verify signature in OCSP response

To verify the signature in an OCSP response the -e or --verify-response parameter is used.
The tool will read an OCSP response in DER format from standard input, or from the file
specified by --load-response. The OCSP response is verified against a set of trust
anchors, which are specified using --load-trust. The trust anchors are concatenated
certificates in PEM format. The certificate that signed the OCSP response needs to be in
the set of trust anchors, or the issuer of the signer certificate needs to be in the set
of trust anchors and the OCSP Extended Key Usage bit has to be asserted in the signer
certificate.

$ ocsptool -e --load-trust issuer.pem --load-response ocsp-response.der

The tool will print status of verification.

Verify signature in OCSP response against given certificate

It is possible to override the normal trust logic if you know that a certain certificate
is supposed to have signed the OCSP response, and you want to use it to check the
signature. This is achieved using --load-signer instead of --load-trust. This will load
one certificate and it will be used to verify the signature in the OCSP response. It will
not check the Extended Key Usage bit.

$ ocsptool -e --load-signer ocsp-signer.pem --load-response ocsp-response.der

This approach is normally only relevant in two situations. The first is when the OCSP
response does not contain a copy of the signer certificate, so the --load-trust code would
fail. The second is if you want to avoid the indirect mode where the OCSP response signer
certificate is signed by a trust anchor.

Real-world example

Here is an example of how to generate an OCSP request for a certificate and to verify the
response. For illustration we'll use the blog.josefsson.org host, which (as of writing)
uses a certificate from CACert. First we'll use gnutls-cli to get a copy of the server
certificate chain. The server is not required to send this information, but this
particular one is configured to do so.

$ echo | gnutls-cli -p 443 blog.josefsson.org --print-cert > chain.pem

Use a text editor on chain.pem to create three files for each separate certificates,
called cert.pem for the first certificate for the domain itself, secondly issuer.pem for
the intermediate certificate and root.pem for the final root certificate.

The domain certificate normally contains a pointer to where the OCSP responder is located,
in the Authority Information Access Information extension. For example, from certtool -i
< cert.pem there is this information:

Authority Information Access Information (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: http://ocsp.CAcert.org/

This means the CA support OCSP queries over HTTP. We are now ready to create a OCSP
request for the certificate.

$ ocsptool --ask ocsp.CAcert.org --load-issuer issuer.pem --load-cert cert.pem --outfile ocsp-response.der

The request is sent via HTTP to the OCSP server address specified. If the address is
ommited ocsptool will use the address stored in the certificate.

EXIT STATUS

       One of the following exit values will be returned:

       0  (EXIT_SUCCESS)
              Successful program execution.

       1  (EXIT_FAILURE)
              The operation failed or the command syntax was not valid.

       70  (EX_SOFTWARE)
              libopts had an internal operational error.  Please report it to autogen-
              users@lists.sourceforge.net.  Thank you.

AUTHORS

       Nikos Mavrogiannopoulos, Simon Josefsson and others; see /usr/share/doc/gnutls/AUTHORS for
       a complete list.

COPYRIGHT

       Copyright (C) 2000-2016 Free Software Foundation, and others all rights reserved.  This
       program is released under the terms of the GNU General Public License, version 3 or later.

BUGS

       Please send bug reports to: bugs@gnutls.org

NOTES

       This manual page was AutoGen-erated from the ocsptool option definitions.