@node ocsptool Invocation

@subsection Invoking ocsptool

@pindex ocsptool

@ignore

#  -*- buffer-read-only: t -*- vi: set ro:

#

# DO NOT EDIT THIS FILE   (invoke-ocsptool.texi)

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# It has been AutoGen-ed

# From the definitions    ../src/ocsptool-args.def

# and the template file   agtexi-cmd.tpl

@end ignore

@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