JWSBuilder when used directly with AsymmetricSignatureSignerContext produces non compliant ECDSA signed JWT

[francis-pouatcha]

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Area

core

Describe the bug

org.keycloak.jose.jws.JWSBuilder when used directly with org.keycloak.crypto.AsymmetricSignatureSignerContext produces non compliant JWT ECDSA signed JWT.

The AsymmetricSignatureSignerContext sings using the java crypto API. The signature produced by Java. The native ECDSA encoding in java is not compatible with the JWS-ECDSA

See issues:

• Client assertion used to broker has invalid ES256, ES384, ES512 signatures #23721
• Remove backward compatibility for ECDSA tokens #23734

Version

latest

Regression

• The issue is a regression

Expected behavior

For EC base signatures, JWSBuilder must throw an exception when passed the AsymmetricSignatureSignerContext and require the use of an algorithm specific Signer like the ECDSASignatureSignerContext, to get the correct behavior like for ECDSA

    # from org.keycloak.crypto.ECDSASignatureSignerContext
    @Override
    public byte[] sign(byte[] data) throws SignatureException {
        try {
            int size = ECDSAAlgorithm.getSignatureLength(getAlgorithm());
            return ECDSAAlgorithm.asn1derToConcatenatedRS(super.sign(data), size);
        } catch (Exception e) {
            throw new SignatureException("Signing failed", e);
        }
    }

Result must be validated by using other progaming languages of jwt.io

Actual behavior

JWS produced using JWSBuilder & AsymmetricSignatureSignerContext can not be validated on jwt.io

How to Reproduce?

The sdjwt String in the test resource core/src/test/resources/7.3-sdjwt.txt contains an invalid jws. THis can be validated using the combination JWSBuilder & AsymmetricSignatureSignerContext. But Can not be read by any jws compliant implementation like jwt.io

Anything else?

We might be having the same problem with EdDSA and the deterministic secret point EdDSA-R follows the same logic as the random point ECDSA-R.

[francis-pouatcha]

Fixed by #29333

[keycloak-github-bot]

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