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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | EXIT STATUS | SEE ALSO | AUTHORS | COPYRIGHT | BUGS | COLOPHON |
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ocsptool(1) User Commands ocsptool(1)
ocsptool - GnuTLS OCSP tool
ocsptool [-flags] [-flag [value]] [--option-name[[=| ]value]]
All arguments must be options.
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.
-d num, --debug=num Enable debugging. This option takes an
integer number as its argument. The value of num is constrained
to being:
in the range 0 through 9999
Specifies the debug level.
-V, --verbose More verbose output.
--infile=file Input file.
--outfile=str Output file.
--ask=server name|url Ask an OCSP/HTTP server on a certificate
validity.
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.
-e, --verify-response Verify response.
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.
-i, --request-info Print information on a OCSP request.
Display detailed information on the provided OCSP request.
-j, --response-info Print information on a OCSP response.
Display detailed information on the provided OCSP response.
-q, --generate-request Generates an OCSP request.
--nonce, --no-nonce Use (or not) a nonce to OCSP request. The
no-nonce form will disable the option.
--load-chain=file Reads a set of certificates forming a chain
from file.
--load-issuer=file Reads issuer's certificate from file.
--load-cert=file Reads the 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.
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.
--load-signer=file Reads the 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.
--outder Use DER format for output of responses (this is the
default).
The output will be in DER encoded format. Unlike other GnuTLS
tools, this is the default for this tool
--outpem Use PEM format for output of responses.
The output will be in PEM format.
-Q file, --load-request=file Reads the DER encoded OCSP request
from file.
-S file, --load-response=file Reads the DER encoded OCSP response
from file.
--ignore-errors Ignore any verification errors.
--verify-allow-broken Allow broken algorithms, such as MD5 for
verification.
This can be combined with --verify-response.
--attime=timestamp Perform validation at the timestamp instead of
the system time.
timestamp is an instance in time encoded as Unix time or in a
human
readable timestring such as "29 Feb 2004", "2004-02-29". Full
documentation available at
<https://www.gnu.org/software/coreutils/manual/html_node/Date-input-formats.html>
or locally via info '(coreutils) date invocation'.
-v arg, --version=arg 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.
-h, --help Display usage information and exit.
-!, --more-help Pass the extended usage information through a
pager.
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 --save-cert chain.pem
The saved certificates normally contain a pointer to where
the OCSP responder is located, in the Authority
Information Access Information extension. For example,
from certtool -i < chain.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: https://ocsp.CAcert.org/
This means that ocsptool can discover the servers to
contact over HTTP. We can now request information on the
chain certificates.
$ ocsptool --ask --load-chain chain.pem
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.
$ ocsptool --ask https://ocsp.CAcert.org/ --load-chain chain.pem
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.
certtool(1)
Copyright (C) 2020-2023 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
Please send bug reports to: bugs@gnutls.org
This page is part of the GnuTLS (GnuTLS Transport Layer Security
Library) project. Information about the project can be found at
⟨http://www.gnutls.org/⟩. If you have a bug report for this
manual page, send it to bugs@gnutls.org. This page was obtained
from the tarball gnutls-3.8.5.tar.xz fetched from
⟨http://www.gnutls.org/download.html⟩ on 2024-06-14. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
3.8.5 04 Apr 2024 ocsptool(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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