OpenSL ocsp(1openssl)
NAME
ocsp - Online Certificate Status Protocol utility
SYNOPSIS
openssl ocsp [-out file] [-issuer file] [-cert file]
[-serial n] [-signer file] [-signkey file] [-signother
file] [-nocerts] [-reqtext] [-resptext] [-text] [-reqout
file] [-respout file] [-reqin file] [-respin file] [-nonce]
[-nononce] [-url URL] [-host host:n] [-path] [-CApath dir]
[-CAfile file] [-VAfile file] [-validityperiod n]
[-statusage n] [-noverify] [-verifyother file]
[-trustother] [-nointern] [-nosignatureverify]
[-nocertverify] [-nochain] [-nocertchecks] [-port num]
[-index file] [-CA file] [-rsigner file] [-rkey file]
[-rother file] [-respnocerts] [-nmin n] [-ndays n]
[-respkeyid] [-nrequest n]
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.
OCSP CLIENT OPTIONS
-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.
-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
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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.
-signother filename
Additional certificates to include in the signed
request.
-nonce, -nononce
Add an OCSP nonce extension to a request or disable OCSP
nonce addition. Normally if an OCSP request is input
using the respin 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 nononce
overrides this.
-reqtext, -resptext, -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 responderurl
specify the responder URL. Both HTP and HTPS (SL/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 HTP path name to use or "/" by default.
-CAfile file, -CApath pathname
file or pathname containing trusted CA certificates.
These are used to verify the signature on the OCSP
response.
-verifyother 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.
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-trustother
the certificates specified by the -verifycerts 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 -verifycerts and
-trustother 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.
-nointern
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 -verifycerts or -VAfile options.
-nosignatureverify
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.
-nocertverify
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.
-nochain
do not use certificates in the response as additional
untrusted CA certificates.
-nocertchecks
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.
-validityperiod nsec, -statusage 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
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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 -validityperiod 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.
OCSP SERVER OPTIONS
-index indexfile
indexfile is 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 respin 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.
-respnocerts
Don't include any certificates in the OCSP response.
-respkeyid
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.
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-port portnum
Port to listen for OCSP requests on. The port may also
be specified using the url option.
-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 OpenSL
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 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
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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 HTP 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 respin 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 and
print it out in text form
openssl ocsp -issuer issuer.pem -cert c1.pem -cert c2.pem \
-url http:/ocsp.myhost.com/ -resptext -respout resp.der
Read in an OCSP response and print out text form:
openssl ocsp -respin resp.der -text
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
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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 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,
write response to a second file.
openssl ocsp -index demoCA/index.txt -rsigner rcert.pem -CA demoCA/cacert.pem
-reqin req.der -respout resp.der
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