openssl-ocsp

OCSP(1SSL) OpenSSL OCSP(1SSL)

NAME
openssl-ocsp, ocsp - Online Certificate Status Protocol utility

SYNOPSIS
openssl ocsp [-help] [-out file] [-issuer file] [-cert file] [-serial
n] [-signer file] [-signkey file] [-sign_other file] [-no_certs]
[-req_text] [-resp_text] [-text] [-reqout file] [-respout file] [-reqin
file] [-respin file] [-nonce] [-no_nonce] [-url URL] [-host host:port]
[-multi process-count] [-header] [-path] [-CApath dir] [-CAfile file]
[-no-CAfile] [-no-CApath] [-attime timestamp] [-check_ss_sig]
[-crl_check] [-crl_check_all] [-explicit_policy] [-extended_crl]
[-ignore_critical] [-inhibit_any] [-inhibit_map] [-no_check_time]
[-partial_chain] [-policy arg] [-policy_check] [-policy_print]
[-purpose purpose] [-suiteB_128] [-suiteB_128_only] [-suiteB_192]
[-trusted_first] [-no_alt_chains] [-use_deltas] [-auth_level num]
[-verify_depth num] [-verify_email email] [-verify_hostname hostname]
[-verify_ip ip] [-verify_name name] [-x509_strict] [-VAfile file]
[-validity_period n] [-status_age n] [-noverify] [-verify_other file]
[-trust_other] [-no_intern] [-no_signature_verify] [-no_cert_verify]
[-no_chain] [-no_cert_checks] [-no_explicit] [-port num] [-ignore_err]
[-index file] [-CA file] [-rsigner file] [-rkey file] [-rother file]
[-rsigopt nm:v] [-resp_no_certs] [-nmin n] [-ndays n] [-resp_key_id]
[-nrequest n] [-digest]

DESCRIPTION
The Online Certificate Status Protocol (OCSP) enables applications to
determine the (revocation) state of an identified certificate (RFC
2560).

The ocsp command performs many common OCSP tasks. It can be used to
print out requests and responses, create requests and send queries to
an OCSP responder and behave like a mini OCSP server itself.

OPTIONS
This command operates as either a client or a server. The options are
described below, divided into those two modes.

OCSP Client Options
-help
Print out a usage message.

-out filename
specify output filename, default is standard output.

-issuer filename
This specifies the current issuer certificate. This option can be
used multiple times. The certificate specified in filename must be
in PEM format. This option MUST come before any -cert options.

-cert filename
Add the certificate filename to the request. The issuer certificate
is taken from the previous issuer option, or an error occurs if no
issuer certificate is specified.

-serial num
Same as the cert option except the certificate with serial number
num is added to the request. The serial number is interpreted as a
decimal integer unless preceded by 0x. Negative integers can also
be specified by preceding the value by a - sign.

-signer filename, -signkey filename
Sign the OCSP request using the certificate specified in the signer
option and the private key specified by the signkey option. If the
signkey option is not present then the private key is read from the
same file as the certificate. If neither option is specified then
the OCSP request is not signed.

-sign_other filename
Additional certificates to include in the signed request.

-nonce, -no_nonce
Add an OCSP nonce extension to a request or disable OCSP nonce
addition. Normally if an OCSP request is input using the reqin
option no nonce is added: using the nonce option will force
addition of a nonce. If an OCSP request is being created (using
cert and serial options) a nonce is automatically added specifying
no_nonce overrides this.

-req_text, -resp_text, -text
Print out the text form of the OCSP request, response or both
respectively.

-reqout file, -respout file
Write out the DER encoded certificate request or response to file.

-reqin file, -respin file
Read OCSP request or response file from file. These option are
ignored if OCSP request or response creation is implied by other
options (for example with serial, cert and host options).

-url responder_url
Specify the responder URL. Both HTTP and HTTPS (SSL/TLS) URLs can
be specified.

-host hostname:port, -path pathname
If the host option is present then the OCSP request is sent to the
host hostname on port port. path specifies the HTTP path name to
use or "/" by default. This is equivalent to specifying -url with
scheme http:// and the given hostname, port, and pathname.

-header name=value
Adds the header name with the specified value to the OCSP request
that is sent to the responder. This may be repeated.

-timeout seconds
Connection timeout to the OCSP responder in seconds. On POSIX
systems, when running as an OCSP responder, this option also limits
the time that the responder is willing to wait for the client
request. This time is measured from the time the responder accepts
the connection until the complete request is received.

-multi process-count
Run the specified number of OCSP responder child processes, with
the parent process respawning child processes as needed. Child
processes will detect changes in the CA index file and
automatically reload it. When running as a responder -timeout
option is recommended to limit the time each child is willing to
wait for the client's OCSP response. This option is available on
POSIX systems (that support the fork() and other required unix
system-calls).

-CAfile file, -CApath pathname
File or pathname containing trusted CA certificates. These are used
to verify the signature on the OCSP response.

-no-CAfile
Do not load the trusted CA certificates from the default file
location

-no-CApath
Do not load the trusted CA certificates from the default directory
location

-attime, -check_ss_sig, -crl_check, -crl_check_all, -explicit_policy,
-extended_crl, -ignore_critical, -inhibit_any, -inhibit_map,
-no_alt_chains, -no_check_time, -partial_chain, -policy, -policy_check,
-policy_print, -purpose, -suiteB_128, -suiteB_128_only, -suiteB_192,
-trusted_first, -use_deltas, -auth_level, -verify_depth, -verify_email,
-verify_hostname, -verify_ip, -verify_name, -x509_strict
Set different certificate verification options. See verify(1)
manual page for details.

-verify_other file
File containing additional certificates to search when attempting
to locate the OCSP response signing certificate. Some responders
omit the actual signer's certificate from the response: this option
can be used to supply the necessary certificate in such cases.

-trust_other
The certificates specified by the -verify_other option should be
explicitly trusted and no additional checks will be performed on
them. This is useful when the complete responder certificate chain
is not available or trusting a root CA is not appropriate.

-VAfile file
File containing explicitly trusted responder certificates.
Equivalent to the -verify_other and -trust_other options.

-noverify
Don't attempt to verify the OCSP response signature or the nonce
values. This option will normally only be used for debugging since
it disables all verification of the responders certificate.

-no_intern
Ignore certificates contained in the OCSP response when searching
for the signers certificate. With this option the signers
certificate must be specified with either the -verify_other or
-VAfile options.

-no_signature_verify
Don't check the signature on the OCSP response. Since this option
tolerates invalid signatures on OCSP responses it will normally
only be used for testing purposes.

-no_cert_verify
Don't verify the OCSP response signers certificate at all. Since
this option allows the OCSP response to be signed by any
certificate it should only be used for testing purposes.

-no_chain
Do not use certificates in the response as additional untrusted CA
certificates.

-no_explicit
Do not explicitly trust the root CA if it is set to be trusted for
OCSP signing.

-no_cert_checks
Don't perform any additional checks on the OCSP response signers
certificate. That is do not make any checks to see if the signers
certificate is authorised to provide the necessary status
information: as a result this option should only be used for
testing purposes.

-validity_period nsec, -status_age age
These options specify the range of times, in seconds, which will be
tolerated in an OCSP response. Each certificate status response
includes a notBefore time and an optional notAfter time. The
current time should fall between these two values, but the interval
between the two times may be only a few seconds. In practice the
OCSP responder and clients clocks may not be precisely synchronised
and so such a check may fail. To avoid this the -validity_period
option can be used to specify an acceptable error range in seconds,
the default value is 5 minutes.

If the notAfter time is omitted from a response then this means
that new status information is immediately available. In this case
the age of the notBefore field is checked to see it is not older
than age seconds old. By default this additional check is not
performed.

-digest
This option sets digest algorithm to use for certificate
identification in the OCSP request. Any digest supported by the
OpenSSL dgst command can be used. The default is SHA-1. This
option may be used multiple times to specify the digest used by
subsequent certificate identifiers.

OCSP Server Options
-index indexfile
The indexfile parameter is the name of a text index file in ca
format containing certificate revocation information.

If the index option is specified the ocsp utility is in responder
mode, otherwise it is in client mode. The request(s) the responder
processes can be either specified on the command line (using issuer
and serial options), supplied in a file (using the reqin option) or
via external OCSP clients (if port or url is specified).

If the index option is present then the CA and rsigner options must
also be present.

-CA file
CA certificate corresponding to the revocation information in
indexfile.

-rsigner file
The certificate to sign OCSP responses with.

-rother file
Additional certificates to include in the OCSP response.

-resp_no_certs
Don't include any certificates in the OCSP response.

-resp_key_id
Identify the signer certificate using the key ID, default is to use
the subject name.

-rkey file
The private key to sign OCSP responses with: if not present the
file specified in the rsigner option is used.

-rsigopt nm:v
Pass options to the signature algorithm when signing OCSP
responses. Names and values of these options are algorithm-
specific.

-port portnum
Port to listen for OCSP requests on. The port may also be specified
using the url option.

-ignore_err
Ignore malformed requests or responses: When acting as an OCSP
client, retry if a malformed response is received. When acting as
an OCSP responder, continue running instead of terminating upon
receiving a malformed request.

-nrequest number
The OCSP server will exit after receiving number requests, default
unlimited.

-nmin minutes, -ndays days
Number of minutes or days when fresh revocation information is
available: used in the nextUpdate field. If neither option is
present then the nextUpdate field is omitted meaning fresh
revocation information is immediately available.

OCSP Response verification.
OCSP Response follows the rules specified in RFC2560.

Initially the OCSP responder certificate is located and the signature
on the OCSP request checked using the responder certificate's public
key.

Then a normal certificate verify is performed on the OCSP responder
certificate building up a certificate chain in the process. The
locations of the trusted certificates used to build the chain can be
specified by the CAfile and CApath options or they will be looked for
in the standard OpenSSL certificates directory.

If the initial verify fails then the OCSP verify process halts with an
error.

Otherwise the issuing CA certificate in the request is compared to the
OCSP responder certificate: if there is a match then the OCSP verify
succeeds.

Otherwise the OCSP responder certificate's CA is checked against the
issuing CA certificate in the request. If there is a match and the
OCSPSigning extended key usage is present in the OCSP responder
certificate then the OCSP verify succeeds.

Otherwise, if -no_explicit is not set the root CA of the OCSP
responders CA is checked to see if it is trusted for OCSP signing. If
it is the OCSP verify succeeds.

If none of these checks is successful then the OCSP verify fails.

What this effectively means if that if the OCSP responder certificate
is authorised directly by the CA it is issuing revocation information
about (and it is correctly configured) then verification will succeed.

If the OCSP responder is a "global responder" which can give details
about multiple CAs and has its own separate certificate chain then its
root CA can be trusted for OCSP signing. For example:

openssl x509 -in ocspCA.pem -addtrust OCSPSigning -out trustedCA.pem

Alternatively the responder certificate itself can be explicitly
trusted with the -VAfile option.

NOTES
As noted, most of the verify options are for testing or debugging
purposes. Normally only the -CApath, -CAfile and (if the responder is
a 'global VA') -VAfile options need to be used.

The OCSP server is only useful for test and demonstration purposes: it
is not really usable as a full OCSP responder. It contains only a very
simple HTTP request handling and can only handle the POST form of OCSP
queries. It also handles requests serially meaning it cannot respond to
new requests until it has processed the current one. The text index
file format of revocation is also inefficient for large quantities of
revocation data.

It is possible to run the ocsp application in responder mode via a CGI
script using the reqin and respout options.

EXAMPLES
Create an OCSP request and write it to a file:

openssl ocsp -issuer issuer.pem -cert c1.pem -cert c2.pem -reqout req.der

Send a query to an OCSP responder with URL http://ocsp.myhost.com/ save
the response to a file, print it out in text form, and verify the
response:

openssl ocsp -issuer issuer.pem -cert c1.pem -cert c2.pem \
-url http://ocsp.myhost.com/ -resp_text -respout resp.der

Read in an OCSP response and print out text form:

openssl ocsp -respin resp.der -text -noverify

OCSP server on port 8888 using a standard ca configuration, and a
separate responder certificate. All requests and responses are printed
to a file.

openssl ocsp -index demoCA/index.txt -port 8888 -rsigner rcert.pem -CA demoCA/cacert.pem
-text -out log.txt

As above but exit after processing one request:

openssl ocsp -index demoCA/index.txt -port 8888 -rsigner rcert.pem -CA demoCA/cacert.pem
-nrequest 1

Query status information using an internally generated request:

openssl ocsp -index demoCA/index.txt -rsigner rcert.pem -CA demoCA/cacert.pem
-issuer demoCA/cacert.pem -serial 1

Query status information using request read from a file, and write the
response to a second file.

openssl ocsp -index demoCA/index.txt -rsigner rcert.pem -CA demoCA/cacert.pem
-reqin req.der -respout resp.der

HISTORY
The -no_alt_chains option was added in OpenSSL 1.1.0.

Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.

1.1.1f 2023-10-10 OCSP(1SSL)

openssl-ocsp

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