NAME
ocsp - Online Certificate Status Protocol utility
LIBRARY
libcrypto, -lcrypto
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] [
-header name
value] [
-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.
- -header name value
- If sending a request to an OCSP server, then the specified
header name and value are added to the HTTP request. Note that the
name and value must be specified as two separate parameters,
not as a single quoted string, and that the header name does not have the
trailing colon. Some OCSP responders require a Host header; use this flag
to provide it.
- -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.