ocspssl - Online in the Cloud

PROGRAM:

NAME

ocsp - Online Certificate Status Protocol utility

SYNOPSIS

openssl ocsp [-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:n] [-path] [-CApath dir] [-CAfile file] [-no_alt_chains]] [-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] [-index file] [-CA file] [-rsigner file] [-rkey file] [-rother
file] [-resp_no_certs] [-nmin n] [-ndays n] [-resp_key_id] [-nrequest n] [-md5|-sha1|...]

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. 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 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 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.

-timeout seconds
connection timeout to the OCSP responder in seconds

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

-no_alt_chains
See verify 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.

-md5|-sha1|-sha256|-ripemod160|...
this option sets digest algorithm to use for certificate identification in the OCSP
request. By default SHA-1 is used.

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 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
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 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 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

HISTORY

The -no_alt_chains options was first added to OpenSSL 1.0.2b.

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