This article includes updates for Nexus OCSP Responder 6.2.4.

This article describes how to specify the OCSP responders that shall handle the incoming OCSP requests (these OCSP responders are referred to as 'the logical OCSP responders', for more information, see Nexus OCSP Responder architecture overview). The specification is done in the "OCSP responder" section of the Nexus OCSP Responder configuration file. There are predefined OCSP responders with different semantics. Use the type parameter to specify which one to use. The workflows for different types of OCSP responders are described in Workflow for Nexus OCSP Responders.

A responder may also forward the request to a remote OCSP responder.
Each responder can support multiple CAs.
Configure a signer for each CA that the responder should support.
In the responders, configure each CA that shall be supported.

The responder replies with status 'Unknown' to OCSP requests for certificates issued by CAs that the responder is not responsible for. When receiving requests related to CAs that are not supported, the first configured signer is used to sign the response. This means that a default "dummy" signing certificate can be configured as the first supported issuer/signer for responding to irrelevant or malicious requests.

Specify the OCSP responders

It is mandatory to specify at least one responder and set the following parameters:

...type
...url
...workers
...signer.x.issuerdn
...signer.x.dn
...signer.x.pin

Authentication, authorization and billing are disabled by default.

For each OCSP responder, specify as follows in the OCSP configuration file:
responder.<r#>.type=[basic|cached|identrus-basic|identrus-cached|non-issued-basic|non-issued-cached|fallback] responder.<r#>.url=[http|https]://<host>[:<port>][/<path>] responder.<r#>.ssl.clientauth=[true|false] responder.<r#>.ssl.certificate=<certificate pattern> responder.<r#>.ssl.pin=<PIN> responder.<r#>.ssl.cipher=<cipher suites> responder.<r#>.ssl.protocol=<protocols> responder.<r#>.workers=<# of workers> responder.<r#>.connections=<# of connections> responder.<r#>.socketreadtimeout=<socket read timeout> responder.<r#>.forwarding.enabled=[true|false] responder.<r#>.signer.<s#>.issuerdn=<distinguished name> responder.<r#>.signer.<s#>.certificate=<certificate pattern> responder.<r#>.signer.<s#>.signingalgorithm=<algorithmname> responder.<r#>.signer.<s#>.pin=<PIN> responder.<r#>.signer.<s#>.setnextupdate=[true|false] responder.<r#>.archivecutoff=[true|false]
See this table for description of constants and values:

Constants and Values	Description

Constants and Values	Description
`<r#>`	Replace `<r#>` with the responder sequence number.
`basic \| cached \| identrus-basic \| identruscached\| non-issued-basic \| non-issuedcached\| fallback`	Enter `basic` to include capabilities for authentication, authorization and billing. These capabilities are included in all of the following. Enter `cached` to add capabilities to those of basic for checking of the response cache. Enter `identrus-basic` to add capabilities to those of basic for no `nextUpdate` in OCSP responses. Enter `identruscached` to add capabilities to those of basic for checking of the response cache, freshness proof and no `nextUpdate` in OCSP responses. Enter `non-issued-basic` to include capabilities for authentication, authorization (extended), validation of non-issued certificates (see Certificate Issuance List - CIL). Enter `non-issued-cached` to add capabilities to those of non-issued-basic for checking of the response cache. Enter `fallback` to activate CF-fallback functionality for requesting the real-time certificate status from CF.
`http \| https`	Enter `http` to indicate that the HTTP protocol shall be used (TLS is not needed). Enter `https` to indicate that the HTTPS protocol shall be used (TLS is needed).
`<host>[:<port>][/<path>]`	Replace `<host>` with the address of the network interface the responder shall listen to. Use "*" if the responder should listen to all the interfaces on this host. If needed, specify also the port and path. Default: The port defaults to 80 when HTTP is used and to 443 for HTTPS.
`true \| false` for parameter `..ssl.clientauth`	If client TLS authentication is required, set this to `true` (HTTPS only). If client TLSauthentication is not required, set this to `false`. Default: `false`
`<certificate pattern>` for parameter `..ssl.certificate`	See Key management section for more information.
`<PIN>` for parameter `..ssl.pin`	See Key management section for more information.
`<cipher suites>` for parameter `..ssl.cipher`	A comma separated list of TLS cipher suites that should be enabled. If HTTPS is enabled, then limit the number of enabled cipher suites to a subset of the default. By default, all the supported cipher suites of Java's SunJSSE provider described in Java Secure Socket Extension (JSSE) Reference Guide for JDK 11 under the section "SunJSSE provider", are enabled.
`<protocols>` for parameter `..ssl.protocol`	A comma separated list of TLS protocols that should be enabled. If HTTPS is enabled, then limit the number of enabled protocols to a subset of the default. By default all the supported protocols of Java's SunJSSE provider described in Java Secure Socket Extension (JSSE) Reference Guide for JDK 11 under the section "SunJSSE provider", are enabled.
`<# of connections>`	Replace `<# of connections>` with the number of allowed connections that can be handled simultaneously. If not specified then the default value of 2000 allowed connections will be set.
`<# of workers>`	Replace `<# of workers>` with the number of requests that can be handled simultaneously. The optimal value depends on the number of processors, processing power and memory.
`<socketreadtimeout>`	Replace `<socketreadtimeout>` with a time period expression (short form), specified according to ISO 8601 Representation of dates and times. After a socket has been opened to the server, the server will wait for this amount of time until it will automatically close the socket if no request has been received. Default: PT1M
`<algorithmname>`	Replace `<algorithmname>` with the requested signature algorithm to sign the response with. The names of the available algorithms are described in Java Cryptography Architecture Standard Algorithm Name Documentation for JDK 11 under the section "Signature Algorithms". If not defined, the signing algorithm will default to `SHA256with<RSA\|ECDSA\|DSA>` or to the algorithm parameter defined in the public key, that is, `RSASSA-PSS`.
`true \| false` for parameter `...forwarding.enabled`	Enter `true` to perform, `false` not to perform forwarding of requests. This enables additional configuration. Read more in "Specify forwarding of requests" below. Default: false.
`<s#>`	Replace `<s#>` with the signer sequence number.
`<distinguished name>`	Replace `<distinguished name>` with the exact distinguished name of the certificate present in the trust store for the issuer to be supported. Run the certadm `list` command to get the syntactically correct distinguished name of each issuer in the trust store. Copying part of the output of that command into the configuration is the recommended way to go when altering the configuration file. See Trust store for further information on how to use the certadm tool.
`<certificate pattern>`	Replace `<certificate pattern>` with the certificate pattern needed to specify the key pair for either the signer or the certificate used for HTTPS. See Key management section for information on how to specify a key. Note that this signer must be the issuer itself, or issued by the certificate specified in `issuerdn`. For a description of the syntax, see Introduction to LDAP.
`<PIN>`	Replace `<PIN>` with the PIN for the key pair used with either the signer or the HTTPS certificate. See Key management section for information on how to specify a key. To encrypt the pin, see Encryption of sensitive configuration parameters.
`true \| false` for parameter `...setnextupdate`	Enter `true` to include, `false` not to include the `NextUpdate` attribute in the response for this signer. Default is `true`.
`true \| false` for parameter `...archivecutoff`	Enter `true` to include, `false` not to include the `ArchiveCutoff` extension in the response for this responder. The extension will use the value from the `ExpiredCertsInCrl` extension in the CRL and will only be added if such extension is found. Default is `false`.

Specify limitations on incoming requests

To read more regarding access control, see Access control and billing.

Specify limitations on the incoming requests to the OCSP responder as follows:
responder.<r#>.incoming.signature.required=[true|false] responder.<r#>.incoming.authorization=[none|bynamematch|byauthentication]
If you enter bynamematch you also have to specify a table of rules to find a match of the distinguished name as follows:
responder.<r#>.incoming.authorization.match.<n#>=<distinguished name>
See also Distinguished name matching and Access control and billing.
In addition, you can also use a certificate pattern to filter allowed client requests, specify as follows:
See this table for description of constants and values:

Constants and Values	Description

Constants and Values	Description
`<r#>`	Replace `<r#>` with the responder sequence number.
`true \| false` for parameter `...signature.required`	Enter `true` to require, `false` not to require the request to be signed. If you intend to perform billing and SSL is not used, enter true. Default: `false`
`none \| bynamematch \| byauthentication`	This configures authorization of the client certificate. If the request is signed, that certificate will be verified during authorization. Otherwise the client certificate used in the TLS handshake will be verified. Enter `none` to indicate that no authorization check shall be performed. Enter `bynamematch` to indicate a search for a match in the specified table. This setting is effective only if either of the parameters `...ssl.clientauth` or `...signature.required` is set to true. Enter `byauthentication` to look for the certificate in the OCSP responders trust store. Default: `none`
`<n#>`	Replace `<n#>` with the name sequence number.
`<distinguished name>`	Replace `<distinguished name>` with the rule to match the distinguished name. Wildcards are allowed.
`<certificate pattern>`	A certificate pattern as described in Introduction to LDAP. Filters authenticated certificates on certificate attributes (part of the authorization scheme). Default is not to filter, which allows any authenticated certificate to bypass the filter mechanism.

Specify responder and responses

In the OCSP configuration file, specify as follows:
See this table for description of constants and values:

Constants and Values	Description

Constants and Values	Description
`<r#>`	Replace `<r#>` with the responder sequence number.
`true \| false` for parameter `...enforceocspsign`	Enter `true` to check, `false` not to check that "OCSP signing" is set in the extension `ExtendedKeyUsage` of the signature certificate(s). Default: `true` If this parameter is set to `true` and `ExtendedKeyUsage` does not contain "OCSP signing", Nexus OCSP Responder will write a message to the log file and stop executing.
`none \| byname \| bykey` for parameter `...othercerts`	Enter `none` to indicate that the response shall include only the signature certificate. Enter `byname` to let Nexus OCSP Responder search the certificate cache for other certificates with the same public key as the signature certificate, but only include those in the response, which also have the same subject distinguished name. Enter `bykey` to let Nexus OCSP Responder search the certificate cache for other certificates with the same public key as the signature certificate and include them in the response. Default: none The parameter `...othercerts` will be ignored if the parameter `...chain` is set to `none`.
`none \| cert \| chain \| allchains`	Enter `none` to indicate that no signature certificate(s) shall be appended to the response. Enter `cert` to indicate that the signature certificate shall be appended to the response. If parameter `...othercerts` is set to "`byname`" or "`bykey`", all applicable certificates shall be appended. Enter `chain` to indicate that one chain of certificates, chaining to the trust store, shall be appended to the response. If parameter `...othercerts` is set to "`byname`" or "`bykey`", one chain for every applicable certificate shall be appended. Enter `allchains` to indicate that all possible certificate chains shall be appended to the response. If parameter `...othercerts` is set to "`byname`" or "`bykey`", all valid chains for all applicable certificates shall be appended. Default: `chain`
`true \| false` for parameter `...includeroot`	Enter `true` to include, `false` not to include the root certificate in the chains. Default: `true` This parameter is relevant only when `...signature.chain` is set to `chain` or `allchains`.
`byname \| bykey \| byski` for parameter `...responderid`	Enter `byname` to identify the responder by its distinguished name in the response. Enter `bykey` to identify the responder by the hash value of its public key. Enter `byski` to identify the responder by the value from the X.509 extension "Subject Key Identifier". Default: `byname`
`true \| false` for parameter `...acceptPlusSignInRequests`	Set this parameter to `true` to make OCSP accept plus signs in incoming requests. Default: `false`
`true \| false` for parameter `...endSpaceInHttpStatusLine`	Use this parameter to align HTTP responses with RFC9112 by adding a space after the status code, even if there isn't a reason-phrase. If set to `true` then the status line will be in the following form: statusline = HTTP-version SP status-code SP [ reason-phrase ] Default: `false`

Specify billing information

Billing is described in Access control and billing.

In the OCSP configuration file, specify as follows:
See this table for description of constants and values:

Constants and Values	Description

Constants and Values	Description
`<r#>`	Replace `<r#>` with the responder sequence number.
`true \| false` for parameter `...billing.enabled`	Enter `true` to enable, `false` not to enable billing. Default: `false`
`true \| false` for parameter `...billing.perrequest`	Enter `true` to count, `false` not to count each request for revocation information the original client request will cause. Default: `true`
`true \| false` for parameter `...billing.percert`	Enter `true` to count, `false` not to count each requested certificate. Default: `true`
`true \| false` for parameter `...billing.countunknown`	Enter `true` to include, or `false` to not include responses with the status "unknown" in logging for `percert`. Default: `false`
`true \| false` for parameter `...billing.includestatus`	Enter `true` to include, or `false` to not include certificate status in logging for `percert`. Default: `false`

Specify forwarding of requests

Forwarding of requests is carried out by the back end OCSP client, which by default will use the settings you made in Back end client section, section"Specify OCSP client request". To override any of these settings, add a new specification here.

Use the same syntax as described for the back end client but replace ocsp.client with responder.<r#>.forwarding.client, where <r#> is the responder sequence number.

Example:

In this example, forwarding is enabled for queries related to certificates issued by the My CA authority.

These three settings are also available:

This setting allows the back end client to modify the request before it is sent to another responder. OCSP forwarding really means "send the message, as it is, to another responder".
Default: false
This setting defines a match table for what issuers that OCSP forwarding should be enabled for. <issuermatch> is matched against the issuer DN. Wildcards are allowed.
If the back end client receives a valid response, this response is sent to the requesting client and the validation is finished. The parameter responseWhenInvalidResponseFromBackEndClient controls what Nexus OCSP Responder will do if the back end client failed to retrieve a valid response.
- Enter unknown to have Nexus OCSP Responder not respond, but rather continue with other modules, such as CRL/CIL checks. This will most likely result in an "unknown" response to the client. Note that this will cause Nexus OCSP Responder to sign the response using the default signer for that responder.
- Enter trylater to have Nexus OCSP Responder pass back "Try later" in the OCSP response.
- Enter internalerror to have Nexus OCSP Responder pass back "Internal error" in the OCSP response.
  Default: trylater

Specify freshness proof

For a description of the freshness proof functionality, see Freshness proof.

In the OCSP configuration file, specify as follows for type=identrus-cached:
See this table for description of constants and values:

Constants and Values	Description

Constants and Values

Description

<r#>

Replace <r#> with the responder sequence number.

true | false

Enter true to add, false not to not add freshness proof.

Default: false

Specify system control

You can configure Nexus OCSP Responder to automatically shut down if an internal error occurs (when the sent OCSP response has internal error status).

In the OCSP configuration file, specify as follows:
Replace <n#> with the number of consecutive internal error responses to return before shutting the system down. A value below 1 disables the functionality.
Default value: -1.

Specify ping data

In the OCSP configuration file, specify ping data as follows:
Replace <data> with a string. When an incoming HTTP POST message contains this data in its body, Nexus OCSP Responder will respond with a simple HTTP 200 OK message and no logs will be produced. This can typically be used by a load balancer to frequently check that the server is up without producing excessive log files in Nexus OCSP Responder.

Examples

View examples

Nexus OCSP responder configuration

In the following examples, different responders are configured. Note that these examples are not complete configurations of the Nexus OCSP Responder.

Nexus OCSP responder proxy configuration

Use this sample configuration to set up Nexus OCSP Responder to forward all incoming OCSP requests to another (OCSP) responder:

Example 1

Use this sample configuration to set up Nexus OCSP Responder to forward all incoming OCSP requests to another (OCSP) responder using client authentication:

Nexus Documentation

OCSP responder section