@node ocsptool Invocation
@subsection Invoking ocsptool
@pindex ocsptool
@ignore
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# DO NOT EDIT THIS FILE (invoke-ocsptool.texi)
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# It has been AutoGen-ed
# From the definitions ../src/ocsptool-args.def
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@subsubheading On verification
Responses are typically signed/issued by designated certificates or
certificate authorities and thus this tool requires on verification
the certificate of the issuer or the full certificate chain in order to
determine the appropriate signing authority. The specified certificate
of the issuer is assumed trusted.
This section was generated by @strong{AutoGen},
using the @code{agtexi-cmd} template and the option descriptions for the @code{ocsptool} program.
This software is released under the GNU General Public License, version 3 or later.
@anchor{ocsptool usage}
@subsubheading ocsptool help/usage (@option{--help})
@cindex ocsptool help
This is the automatically generated usage text for ocsptool.
The text printed is the same whether selected with the @code{help} option
(@option{--help}) or the @code{more-help} option (@option{--more-help}). @code{more-help} will print
the usage text by passing it through a pager program.
@code{more-help} is disabled on platforms without a working
@code{fork(2)} function. The @code{PAGER} environment variable is
used to select the program, defaulting to @file{more}. Both will exit
with a status code of 0.
@exampleindent 0
@example
ocsptool - GnuTLS OCSP tool
Usage: ocsptool [ -<flag> [<val>] | --<name>[@{=| @}<val>] ]...
-d, --debug=num Enable debugging
- it must be in the range:
0 to 9999
-V, --verbose More verbose output
- may appear multiple times
--infile=file Input file
- file must pre-exist
--outfile=str Output file
--ask[=arg] Ask an OCSP/HTTP server on a certificate validity
-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 Generates an OCSP request
--nonce Use (or not) a nonce to OCSP request
- disabled as '--no-nonce'
--load-chain=file Reads a set of certificates forming a chain from file
- file must pre-exist
--load-issuer=file Reads issuer's certificate from file
- file must pre-exist
--load-cert=file Reads the certificate to check from file
- file must pre-exist
--load-trust=file Read OCSP trust anchors from file
- prohibits the option 'load-signer'
- file must pre-exist
--load-signer=file Reads the OCSP response signer from file
- prohibits the option 'load-trust'
- file must pre-exist
--inder Use DER format for input certificates and private keys
- disabled as '--no-inder'
--outder Use DER format for output of responses (this is the default)
--outpem Use PEM format for output of responses
-Q, --load-request=file Reads the DER encoded OCSP request from file
- file must pre-exist
-S, --load-response=file Reads the DER encoded OCSP response from file
- file must pre-exist
--ignore-errors Ignore any verification errors
--verify-allow-broken Allow broken algorithms, such as MD5 for verification
-v, --version[=arg] output version information and exit
-h, --help display extended usage information and exit
-!, --more-help extended usage information passed thru pager
Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
ocsptool is a program that can parse and print information about OCSP
requests/responses, generate requests and verify responses. Unlike other
GnuTLS applications it outputs DER encoded structures by default unless the
'--outpem' option is specified.
@end example
@exampleindent 4
@anchor{ocsptool debug}
@subsubheading debug option (-d)
This is the ``enable debugging'' option.
This option takes a number argument.
Specifies the debug level.
@anchor{ocsptool ask}
@subsubheading ask option
This is the ``ask an ocsp/http server on a certificate validity'' option.
This option takes an optional string argument @file{server name|url}.
Connects to the specified HTTP OCSP server and queries on the validity of the loaded certificate.
Its argument can be a URL or a plain server name. It can be combined with --load-chain, where it checks
all certificates in the provided chain, or with --load-cert and
--load-issuer options. The latter checks the provided certificate
against its specified issuer certificate.
@anchor{ocsptool verify-response}
@subsubheading verify-response option (-e)
This is the ``verify response'' option.
Verifies the provided OCSP response against the system trust
anchors (unless --load-trust is provided). It requires the --load-signer
or --load-chain options to obtain the signer of the OCSP response.
@anchor{ocsptool request-info}
@subsubheading request-info option (-i)
This is the ``print information on a ocsp request'' option.
Display detailed information on the provided OCSP request.
@anchor{ocsptool response-info}
@subsubheading response-info option (-j)
This is the ``print information on a ocsp response'' option.
Display detailed information on the provided OCSP response.
@anchor{ocsptool load-trust}
@subsubheading load-trust option
This is the ``read ocsp trust anchors from file'' option.
This option takes a file argument.
@noindent
This option has some usage constraints. It:
@itemize @bullet
@item
must not appear in combination with any of the following options:
load-signer.
@end itemize
When verifying an OCSP response read the trust anchors from the
provided file. When this is not provided, the system's trust anchors will be
used.
@anchor{ocsptool outder}
@subsubheading outder option
This is the ``use der format for output of responses (this is the default)'' option.
The output will be in DER encoded format. Unlike other GnuTLS tools, this is the default for this tool
@anchor{ocsptool outpem}
@subsubheading outpem option
This is the ``use pem format for output of responses'' option.
The output will be in PEM format.
@anchor{ocsptool verify-allow-broken}
@subsubheading verify-allow-broken option
This is the ``allow broken algorithms, such as md5 for verification'' option.
This can be combined with --verify-response.
@anchor{ocsptool exit status}
@subsubheading ocsptool exit status
One of the following exit values will be returned:
@table @samp
@item 0 (EXIT_SUCCESS)
Successful program execution.
@item 1 (EXIT_FAILURE)
The operation failed or the command syntax was not valid.
@end table
@anchor{ocsptool See Also}
@subsubheading ocsptool See Also
certtool (1)
@anchor{ocsptool Examples}
@subsubheading ocsptool Examples
@subsubheading Print information about an OCSP request
To parse an OCSP request and print information about the content, the
@code{-i} or @code{--request-info} parameter may be used as follows.
The @code{-Q} parameter specify the name of the file containing the
OCSP request, and it should contain the OCSP request in binary DER
format.
@example
$ ocsptool -i -Q ocsp-request.der
@end example
The input file may also be sent to standard input like this:
@example
$ cat ocsp-request.der | ocsptool --request-info
@end example
@subsubheading Print information about an OCSP response
Similar to parsing OCSP requests, OCSP responses can be parsed using
the @code{-j} or @code{--response-info} as follows.
@example
$ ocsptool -j -Q ocsp-response.der
$ cat ocsp-response.der | ocsptool --response-info
@end example
@subsubheading Generate an OCSP request
The @code{-q} or @code{--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 @code{--outfile}. To generate an OCSP request the issuer of the
certificate to check needs to be specified with @code{--load-issuer}
and the certificate to check with @code{--load-cert}. By default PEM
format is used for these files, although @code{--inder} can be used to
specify that the input files are in DER format.
@example
$ ocsptool -q --load-issuer issuer.pem --load-cert client.pem \
--outfile ocsp-request.der
@end example
When generating OCSP requests, the tool will add an OCSP extension
containing a nonce. This behaviour can be disabled by specifying
@code{--no-nonce}.
@subsubheading Verify signature in OCSP response
To verify the signature in an OCSP response the @code{-e} or
@code{--verify-response} parameter is used. The tool will read an
OCSP response in DER format from standard input, or from the file
specified by @code{--load-response}. The OCSP response is verified
against a set of trust anchors, which are specified using
@code{--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.
@example
$ ocsptool -e --load-trust issuer.pem \
--load-response ocsp-response.der
@end example
The tool will print status of verification.
@subsubheading 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
@code{--load-signer} instead of @code{--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.
@example
$ ocsptool -e --load-signer ocsp-signer.pem \
--load-response ocsp-response.der
@end example
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 @code{--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.
@subsubheading 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 @code{blog.josefsson.org} host, which (as of writing) uses a
certificate from CACert. First we'll use @code{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.
@example
$ echo | gnutls-cli -p 443 blog.josefsson.org --save-cert chain.pem
@end example
The saved certificates normally contain a pointer to where the OCSP
responder is located, in the Authority Information Access Information
extension. For example, from @code{certtool -i < chain.pem} there is
this information:
@example
Authority Information Access Information (not critical):
Access Method: 1.3.6.1.5.5.7.48.1 (id-ad-ocsp)
Access Location URI: https://ocsp.CAcert.org/
@end example
This means that ocsptool can discover the servers to contact over HTTP.
We can now request information on the chain certificates.
@example
$ ocsptool --ask --load-chain chain.pem
@end example
The request is sent via HTTP to the OCSP server address found in
the certificates. It is possible to override the address of the
OCSP server as well as ask information on a particular certificate
using --load-cert and --load-issuer.
@example
$ ocsptool --ask https://ocsp.CAcert.org/ --load-chain chain.pem
@end example