ocsptool man page on Manjaro

ocsptool man page on Manjaro

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ocsptool(1) User Commands ocsptool(1)

NAME
ocsptool - GnuTLS OCSP tool

SYNOPSIS
ocsptool [-flag [value]]... [--opt-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, --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, --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 parame‐
ter 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 con‐
taining 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 cer‐
tificates 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 cer‐
tificate, so the --load-trust code would fail. The second is if you
want to avoid the indirect mode where the OCSP response signer certifi‐
cate 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.josef‐
sson.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 cer‐
tificate.

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.