OCSP validation in snmp4j TLSTM

AGENTPP · August 19, 2021, 1:21pm

Hi Vikas,
I suggest to try JRE 16 too, because there were a lot of changes and fixes on the TLS engine between version 9 and 16.
I will first try to reproduce it with the latest version by end of next week. The versions 15 and above have even better debugging output available.
Hope this helps anyway.
Best regards
Frank

tvikasv · August 20, 2021, 9:03pm

Hi Frank ,
I tried with JDK 16 , still the behavior is same . Connection was successfully established even with revoked certificate.
Please let me know if you need any details w.r.t logs or the self signed certificate which I have used.

Regards ,
Vikas

tvikasv · September 9, 2021, 2:07pm

Hi Frank,
By any chance where you able to check this ?

As per the java documentation we need to use setRevocationEnabled method on PKIXParameters setting the ocsp.enable property to "true" .
https://docs.oracle.com/javase/10/security/java-pki-programmers-guide.htm#JSSEC-GUID-E6E737DB-4000-4005-969E-BCD0238B1566

I did not find any code related to setRevocationEnabled in snmp4j .

So I tried adding it in TLSTMUtil but still the behavior was same (Connection was successful for revoked certificate )

Regards,
Vikas

AGENTPP · September 9, 2021, 10:12pm

I need some more days to be able to setup a unit test for this. But I think initializing the PKIXParameters class with the key store that contains the revoked certificate does not make any sense. But I need to verify this assumption reading the JDK source code - the documentation is unclear about this.

AGENTPP · September 28, 2021, 7:34pm

In the Oracle JDK 13 source code I found:

/**
 * Flag indicating whether to enable revocation check for the PKIX trust
 * manager. Typically, this will only work if the PKIX implementation
 * supports CRL distribution points as we do not manually setup CertStores.
 */
private static final boolean checkTLSRevocation = GetBooleanAction
        .privilegedGetProperty("com.sun.net.ssl.checkRevocation");

and in the same class PKIXValidator:

/**
 * Set J2SE global default PKIX parameters. Currently, hardcoded to disable
 * revocation checking. In the future, this should be configurable.
 */
private void setDefaultParameters(String variant) {
    if ((variant == Validator.VAR_TLS_SERVER) ||
            (variant == Validator.VAR_TLS_CLIENT)) {
        parameterTemplate.setRevocationEnabled(checkTLSRevocation);
    } else {
        parameterTemplate.setRevocationEnabled(false);
    }
}

That means, maybe it works with setting the com.sun.net.ssl.checkRevocation system property to true. But that would be a non-portable solution, of course.

Therefore I am going to implement a generic revocation check that can be enabled programmatically using the SNMP4J API.

tvikasv · September 29, 2021, 7:56am

Thank you Frank.

Would we have the support for below mentioned points in next release ?

Support for OCSP (revocation check) from SNMP4J API
Support for Bouncy castle Keystore ( Support for Bouncy castle Keystore - #5 by AGENTPP ).

Can you please let us know when can we expect(approximate) the next release to be available ?

AGENTPP · September 29, 2021, 9:08pm

The new release will be available latest first week of November 2021, but I hope that there no problems during implementation of the revocation support function and then it could be ready one or two weeks earlier.

AGENTPP · October 19, 2021, 12:34am

The revocation checking based on CRL file or OCSP is working for TLSTM in the latest SNMP4J 3.6.0-SNAPSHOT.

In any case, CRL/OSCP revocation checking will be disabled by default, because it consumes a lot of performance during handshake.

BTW, when revocation checking is switched on by

System.setProperty("com.sun.net.ssl.checkRevocation", "true");

then it seems that it cannot be switched in the same VM anymore back to “false”. Does anyone know how to work around this behaviour?

AGENTPP · October 21, 2021, 7:45pm

Documentation on how to enable TLS certificate revocation checking with SNMP4J 3.6.0 or later can be found here:
https://doc.snmp.app/pages/viewpage.action?pageId=83525633

tvikasv · October 22, 2021, 7:51am

Thank you Frank for the support .

I will run a test and update on this.

Can I clone the SNMP4J 3.6.0 source code ? If so please share the link to clone the same .

Regards,
Vikas

AGENTPP · October 22, 2021, 7:56pm

Hi Vikas,
Cloning is not (yet) possible, although I am working on a secure and mostly automated process for doing that in the near future.
Best regards
Frank

tvikasv · November 30, 2021, 4:27pm

Hi Frank ,

I used SNMP4J 3.6.0 and I don’t see the certificate validation getting failed for revoked certificate(Connection establishment successful for revoked certificate)

Have set both the properties as recommended in server side as well as client side .

I don’t see any logs related to connection establishment to OCSP server as well .

ENV:
SNMP4J 3.6.0
Java 16

AGENTPP · November 30, 2021, 5:35pm

I think besides the code you quoted you need to set the PKIXRevocationChecker with TLSTM.setPKIXRevocationChecker and create such a checker like the default one available with TLSTMUtil.createDefaultPKIXRevocationChecker() because current Java version do not actually do the revocation checking unless custom revocation checkers (i.e. PKIXBuilderParameters) are used:

/**
 * Creates a default revocation checker with CRL check only (no OCSP) and check is limited to end entity only.
 * @return
 *    a simple revocation checker to be used with {@link #setPKIXRevocationChecker(PKIXRevocationChecker)}.
 * @since 3.6.0
 */
public static PKIXRevocationChecker createDefaultPKIXRevocationChecker() {
    CertPathBuilder cpb;
    try {
        cpb = CertPathBuilder.getInstance(TrustManagerFactory.getDefaultAlgorithm());
    } catch (NoSuchAlgorithmException e) {
        throw new RuntimeException(e);
    }
    PKIXRevocationChecker revocationChecker = (PKIXRevocationChecker)cpb.getRevocationChecker();
    // Relaxed checking - avoid OCSP because of 33% overhead on TLS connection creation:
    revocationChecker.setOptions(EnumSet.of(
            PKIXRevocationChecker.Option.PREFER_CRLS, // prefer CLR over OCSP
            PKIXRevocationChecker.Option.ONLY_END_ENTITY,
            PKIXRevocationChecker.Option.NO_FALLBACK)); // do not fall back to OCSP
    return revocationChecker;
}

tvikasv · December 8, 2021, 4:54pm

Hi Frank ,
Can you please help with some sample implementation for OCSP using snmp4j ?
Some how I am ending up with same issue where the revocation check for OCSP is not happening and the connection gets established even for a revoked certificate .

Below is the procedure to where I used run the local OCS server using openssl .

#This requires the support of OpenSSL in your machine. So please install OpenSSL if it is not already installed.
An OpenSSL CA requires few files and some supporting directories to work. Follow the below commands to create that folder structure(Create the directory structure according to your openssl.cnf).

mkdir -p demoCA/newcerts
touch demoCA/index.txt
echo ‘01’ > demoCA/serial

Copy the content of the openssl.cnf into a separate file. We will be using this new file as the configuration file to create certificates, certificate signing requests and etc. Here I have renamed it as validation.cnf. Add the following line under the section [ usr_cert ].
[ usr_cert ]
authorityInfoAccess = OCSP;URI:http://127.0.0.1:8080
Create a new stanza in validation.cnf as follows,
[ v3_OCSP ]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
extendedKeyUsage = OCSPSigning
For this example, the OCSP server will be running on 127.0.0.1 on port 8080 as given in authorityInfoAccess extension.
Create a private key for root CA.

openssl genrsa -out rootCA.key 1024

Based on this key, generate a CA certificate which is valid for 10 years based on the root CA’ s private key.

openssl req -new -x509 -days 3650 -key rootCA.key -out rootCA.crt -config validation.cnf

Create another private key to be used as the end user private key.

openssl genrsa -out certKey.key 1024

Create an end user certificate based on the generated private key.

openssl req -new -x509 -days 3650 -key certKey.key -out certificate.crt -config validation.cnf

Generate the certificate signing request(CSR) for the generated end-user certificate.

openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey certKey.key

Sign the client certificate, using above created CA and include CRL URLs and OCSP URLs in the certificate

openssl ca -batch -startdate 210709080000Z -enddate 250813090000Z -keyfile rootCA.key -cert rootCA.crt -policy policy_anything -config validation.cnf -notext -out certificate.crt -infiles CSR.csr

Creating the OCSP server
In order to host an OCSP server, an OCSP signing certificate has to be generated. Run following 2 commands.

openssl req -new -nodes -out ocspSigning.csr -keyout ocspSigning.key
openssl ca -keyfile rootCA.key -cert rootCA.crt -in ocspSigning.csr -out ocspSigning.crt -config “/cygdrive/c/Users/vvittala/workspace/CeritFolder/OCSP/validation.cnf”

Start OCSP Server. Switch to a new terminal and run,
openssl ocsp -index demoCA/index.txt -port 8080 -rsigner ocspSigning.crt -rkey ocspSigning.key -CA rootCA.crt -text -out log.txt &
Verify Certificate Revocation. Switch to a new terminal and run
openssl ocsp -CAfile rootCA.crt -issuer rootCA.crt -cert certificate.crt -url http://127.0.0.1:8080 -resp_text -noverify
This will show that the certificate status is good.

Revoke a certificate
If you want to revoke the certificate run following command
openssl ca -keyfile rootCA.key -cert rootCA.crt -revoke certificate.crt
2. Then restart the OCSP server.
openssl ocsp -index demoCA/index.txt -port 8080 -rsigner ocspSigning.crt -rkey ocspSigning.key -CA rootCA.crt -text -out log.txt &
3. Verify Certificate Revocation. Switch to a new terminal and run
openssl ocsp -CAfile rootCA.crt -issuer rootCA.crt -cert certificate.crt -url http://127.0.0.1:8080 -resp_text -noverify
This will show that the certificate status as revoked.

AGENTPP · December 9, 2021, 1:15am

I do not think that a JRE will accept a OCSP server without https certificate.

But that should be reported by Java in their extended java.net.ssl debug output.
Have you checked that output? What is the reason that OCSP is not recognizing the revocation?

tvikasv · December 9, 2021, 8:32am

Hi Frank ,

That’s the issue, we don’t see loggings w.r.t OCSP .

PFA the filtered javax.net.ssl logs .

Regards,
Vikas

AGENTPP · December 12, 2021, 11:32pm

I have no idea what is going wrong with your setup, except that “http” will not work as OCSP server address.

tvikasv · January 11, 2022, 9:42am

Hi Frank ,
Is there a way we can get the server side certificate and issue certificate from the TLS connection or session object in the application where we use snmp4J.

Also if possible please let us know if the sample program where the OCSP validation is tried using snmp4j .

Regards,
Vikas

AGENTPP · January 11, 2022, 10:55pm

Hi Vikas,

I cannot answer your first question, please check the Java documentation.
Second: Have a look at the SNMP4J TLSTMTestWithCertRevocationChecking unit test.

Best regards,
Frank

tvikasv · January 25, 2022, 7:27am

Hi Frank ,

With the unit tests which you shared looks like it might work for certificate revocation lists (CRL) .

We are looking for OCSP method where the certificate contains the OCSP URL

or by setting the URL as security property Security.setProperty(“ocsp.responderURL”,“http://127.0.0.1:8080”);

In TLSTMTestWithCertRevocationChecking unit test we don’t see the OCSP url being used neither in the code nor in the certificates .

Can you please confirm if OCSP support is available in snmp4j and the specific tests are available and are executed successfully.