ocsp
OCSP(1) OpenSSL OCSP(1)
NAME
ocsp - Online Certificate Status Protocol utility
SYNOPSIS
openssl ocsp [-out file] [-issuer file] [-cert file] [-serial n]
[-req_text] [-resp_text] [-text] [-reqout file] [-respout file] [-reqin
file] [-respin file] [-nonce] [-no_nonce] [-url responder_url] [-host
host:n] [-path] [-CApath file] [-CAfile file] [-VAfile file] [-ver-
ify_certs file] [-noverify] [-trust_other] [-no_intern] [-no_sig_ver-
ify] [-no_cert_verify] [-no_chain] [-no_cert_checks] [-validity_period
nsec] [-status_age nsec]
DESCRIPTION
WARNING: this documentation is preliminary and subject to change.
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 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.
-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 respin
option no nonce is added: using the nonce option will force addi-
tion 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.
-CAfile file, -CApath pathname
file or pathname containing trusted CA certificates. These are used
to verify the signature on the OCSP response.
-verify_certs 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_certs 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. Equiva-
lent to the -verify_certs 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 certifi-
cate must be specified with either the -verify_certs or -VAfile
options.
-no_sig_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 certifi-
cate it should only be used for testing purposes.
-no_chain
do not use certificates in the response as additional untrusted CA
certificates.
-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 test-
ing 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 cur-
rent 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 per-
formed.
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.
-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.
-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 revoca-
tion 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 loca-
tions of the trusted certificates used to build the chain can be speci-
fied 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 cer-
tificate 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 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 pur-
poses. 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 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/ -resp_text -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 sepa-
rate 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 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
0.9.7a 2001-09-07 OCSP(1)
