KEYCLOAK-15015 Extend KeyWrapper to add whole certificate chain in x5c parameter (#7643)

* [KEYCLOAK-15015] - Publishing the x5c for JWK

Co-authored-by: Vetle Bergstad <vetle.bergstad@evry.com>
Co-authored-by: Pedro Igor <pigor.craveiro@gmail.com>

core/src/main/java/org/keycloak/crypto/KeyWrapper.java

@@ -16,6 +16,7 @@
  */
 package org.keycloak.crypto;
 
+import java.util.List;
 import javax.crypto.SecretKey;
 import java.security.Key;
 import java.security.cert.X509Certificate;
@@ -33,6 +34,7 @@ public class KeyWrapper {
     private Key publicKey;
     private Key privateKey;
     private X509Certificate certificate;
+    private List<X509Certificate> certificateChain;
 
     public String getProviderId() {
         return providerId;
@@ -122,4 +124,12 @@ public class KeyWrapper {
         this.certificate = certificate;
     }
 
+    public List<X509Certificate> getCertificateChain() {
+        return certificateChain;
+    }
+
+    public void setCertificateChain(List<X509Certificate> certificateChain) {
+        this.certificateChain = certificateChain;
+    }
+
 }

core/src/main/java/org/keycloak/jose/jwk/JWKBuilder.java

@@ -17,6 +17,8 @@
 
 package org.keycloak.jose.jwk;
 
+import java.util.Collections;
+import java.util.List;
 import org.keycloak.common.util.Base64Url;
 import org.keycloak.common.util.KeyUtils;
 import org.keycloak.common.util.PemUtils;
@@ -65,10 +67,14 @@ public class JWKBuilder {
     }
 
     public JWK rsa(Key key) {
-        return rsa(key, (X509Certificate)null);
+        return rsa(key, (List<X509Certificate>) null);
     }
     
     public JWK rsa(Key key, X509Certificate certificate) {
+        return rsa(key, Collections.singletonList(certificate));
+    }
+
+    public JWK rsa(Key key, List<X509Certificate> certificates) {
         RSAPublicKey rsaKey = (RSAPublicKey) key;
 
         RSAPublicJWK k = new RSAPublicJWK();
@@ -81,8 +87,12 @@ public class JWKBuilder {
         k.setModulus(Base64Url.encode(toIntegerBytes(rsaKey.getModulus())));
         k.setPublicExponent(Base64Url.encode(toIntegerBytes(rsaKey.getPublicExponent())));
 
-        if (certificate != null) {
-            k.setX509CertificateChain(new String [] {PemUtils.encodeCertificate(certificate)});
+        if (certificates != null && !certificates.isEmpty()) {
+            String[] certificateChain = new String[certificates.size()];
+            for (int i = 0; i < certificates.size(); i++) {
+                certificateChain[i] = PemUtils.encodeCertificate(certificates.get(i));
+            }
+            k.setX509CertificateChain(certificateChain);
         }
 
         return k;

core/src/test/java/org/keycloak/jose/jwk/JWKTest.java

@@ -17,9 +17,10 @@
 
 package org.keycloak.jose.jwk;
 
+import java.util.Arrays;
+import java.util.List;
 import org.junit.Test;
 import org.keycloak.common.util.Base64Url;
-import org.keycloak.common.util.CertificateUtils;
 import org.keycloak.common.util.KeyUtils;
 import org.keycloak.common.util.PemUtils;
 import org.keycloak.crypto.JavaAlgorithm;
@@ -37,6 +38,7 @@ import java.security.cert.X509Certificate;
 import java.security.spec.ECGenParameterSpec;
 
 import static org.junit.Assert.*;
+import static org.keycloak.common.util.CertificateUtils.*;
 
 /**
  * @author <a href="mailto:sthorger@redhat.com">Stian Thorgersen</a>
@@ -47,7 +49,7 @@ public class JWKTest {
     public void publicRs256() throws Exception {
         KeyPair keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair();
         PublicKey publicKey = keyPair.getPublic();
-        X509Certificate certificate = CertificateUtils.generateV1SelfSignedCertificate(keyPair, "Test");
+        X509Certificate certificate = generateV1SelfSignedCertificate(keyPair, "Test");
 
         JWK jwk = JWKBuilder.create().kid(KeyUtils.createKeyId(publicKey)).algorithm("RS256").rsa(publicKey, certificate);
 
@@ -78,6 +80,47 @@ public class JWKTest {
         verify(data, sign, JavaAlgorithm.RS256, publicKeyFromJwk);
     }
 
+    @Test
+    public void publicRs256Chain() throws Exception {
+        KeyPair keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair();
+        PublicKey publicKey = keyPair.getPublic();
+        List<X509Certificate> certificates = Arrays.asList(generateV1SelfSignedCertificate(keyPair, "Test"), generateV1SelfSignedCertificate(keyPair, "Intermediate"));
+
+        JWK jwk = JWKBuilder.create().kid(KeyUtils.createKeyId(publicKey)).algorithm("RS256").rsa(publicKey, certificates);
+
+        assertNotNull(jwk.getKeyId());
+        assertEquals("RSA", jwk.getKeyType());
+        assertEquals("RS256", jwk.getAlgorithm());
+        assertEquals("sig", jwk.getPublicKeyUse());
+
+        assertTrue(jwk instanceof RSAPublicJWK);
+        assertNotNull(((RSAPublicJWK) jwk).getModulus());
+        assertNotNull(((RSAPublicJWK) jwk).getPublicExponent());
+        assertNotNull(((RSAPublicJWK) jwk).getX509CertificateChain());
+
+        String[] expectedChain = new String[certificates.size()];
+        for (int i = 0; i < certificates.size(); i++) {
+            expectedChain[i] = PemUtils.encodeCertificate(certificates.get(i));
+        }
+
+        assertArrayEquals(expectedChain, ((RSAPublicJWK) jwk).getX509CertificateChain());
+        assertNotNull(((RSAPublicJWK) jwk).getSha1x509Thumbprint());
+        assertEquals(PemUtils.generateThumbprint(((RSAPublicJWK) jwk).getX509CertificateChain(), "SHA-1"), ((RSAPublicJWK) jwk).getSha1x509Thumbprint());
+        assertNotNull(((RSAPublicJWK) jwk).getSha256x509Thumbprint());
+        assertEquals(PemUtils.generateThumbprint(((RSAPublicJWK) jwk).getX509CertificateChain(), "SHA-256"), ((RSAPublicJWK) jwk).getSha256x509Thumbprint());
+
+        String jwkJson = JsonSerialization.writeValueAsString(jwk);
+
+        PublicKey publicKeyFromJwk = JWKParser.create().parse(jwkJson).toPublicKey();
+
+        // Parse
+        assertArrayEquals(publicKey.getEncoded(), publicKeyFromJwk.getEncoded());
+
+        byte[] data = "Some test string".getBytes(StandardCharsets.UTF_8);
+        byte[] sign = sign(data, JavaAlgorithm.RS256, keyPair.getPrivate());
+        verify(data, sign, JavaAlgorithm.RS256, publicKeyFromJwk);
+    }
+
     @Test
     public void publicEs256() throws Exception {
         Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

services/src/main/java/org/keycloak/keys/AbstractRsaKeyProvider.java

@@ -19,11 +19,7 @@ package org.keycloak.keys;
 
 import org.keycloak.common.util.KeyUtils;
 import org.keycloak.component.ComponentModel;
-import org.keycloak.crypto.Algorithm;
-import org.keycloak.crypto.KeyStatus;
-import org.keycloak.crypto.KeyType;
-import org.keycloak.crypto.KeyUse;
-import org.keycloak.crypto.KeyWrapper;
+import org.keycloak.crypto.*;
 import org.keycloak.models.RealmModel;
 
 import java.security.KeyPair;
@@ -66,6 +62,10 @@ public abstract class AbstractRsaKeyProvider implements KeyProvider {
     }
 
     protected KeyWrapper createKeyWrapper(KeyPair keyPair, X509Certificate certificate) {
+        return createKeyWrapper(keyPair, certificate, Collections.emptyList());
+    }
+
+    protected KeyWrapper createKeyWrapper(KeyPair keyPair, X509Certificate certificate, List<X509Certificate> certificateChain) {
         KeyWrapper key = new KeyWrapper();
 
         key.setProviderId(model.getId());
@@ -80,6 +80,14 @@ public abstract class AbstractRsaKeyProvider implements KeyProvider {
         key.setPublicKey(keyPair.getPublic());
         key.setCertificate(certificate);
 
+        if (!certificateChain.isEmpty()) {
+            if (certificate != null && !certificate.equals(certificateChain.get(0))) {
+                // just in case the chain does not contain the end-user certificate
+                certificateChain.add(0, certificate);
+            }
+            key.setCertificateChain(certificateChain);
+        }
+
         return key;
     }
 

services/src/main/java/org/keycloak/keys/JavaKeystoreKeyProvider.java

@@ -27,6 +27,7 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.security.GeneralSecurityException;
 import java.security.KeyPair;
 import java.security.KeyStore;
 import java.security.KeyStoreException;
@@ -34,8 +35,20 @@ import java.security.NoSuchAlgorithmException;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.UnrecoverableKeyException;
+import java.security.cert.CertPath;
+import java.security.cert.CertPathValidator;
 import java.security.cert.CertificateException;
+import java.security.cert.CertificateFactory;
+import java.security.cert.PKIXParameters;
+import java.security.cert.TrustAnchor;
 import java.security.cert.X509Certificate;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 /**
  * @author <a href="mailto:sthorger@redhat.com">Stian Thorgersen</a>
@@ -52,17 +65,18 @@ public class JavaKeystoreKeyProvider extends AbstractRsaKeyProvider {
             KeyStore keyStore = KeyStore.getInstance("JKS");
             keyStore.load(is, model.get(JavaKeystoreKeyProviderFactory.KEYSTORE_PASSWORD_KEY).toCharArray());
 
-            PrivateKey privateKey = (PrivateKey) keyStore.getKey(model.get(JavaKeystoreKeyProviderFactory.KEY_ALIAS_KEY), model.get(JavaKeystoreKeyProviderFactory.KEY_PASSWORD_KEY).toCharArray());
+            String keyAlias = model.get(JavaKeystoreKeyProviderFactory.KEY_ALIAS_KEY);
+            PrivateKey privateKey = (PrivateKey) keyStore.getKey(keyAlias, model.get(JavaKeystoreKeyProviderFactory.KEY_PASSWORD_KEY).toCharArray());
             PublicKey publicKey = KeyUtils.extractPublicKey(privateKey);
 
             KeyPair keyPair = new KeyPair(publicKey, privateKey);
 
-            X509Certificate certificate = (X509Certificate) keyStore.getCertificate(model.get(JavaKeystoreKeyProviderFactory.KEY_ALIAS_KEY));
+            X509Certificate certificate = (X509Certificate) keyStore.getCertificate(keyAlias);
             if (certificate == null) {
                 certificate = CertificateUtils.generateV1SelfSignedCertificate(keyPair, realm.getName());
             }
 
-            return createKeyWrapper(keyPair, certificate);
+            return createKeyWrapper(keyPair, certificate, loadCertificateChain(keyStore, keyAlias));
         } catch (KeyStoreException kse) {
             throw new RuntimeException("KeyStore error on server. " + kse.getMessage(), kse);
         } catch (FileNotFoundException fnfe) {
@@ -75,7 +89,49 @@ public class JavaKeystoreKeyProvider extends AbstractRsaKeyProvider {
             throw new RuntimeException("Certificate error on server. " + ce.getMessage(), ce);
         } catch (UnrecoverableKeyException uke) {
             throw new RuntimeException("Keystore on server can not be recovered. " + uke.getMessage(), uke);
+        } catch (GeneralSecurityException gse) {
+            throw new RuntimeException("Invalid certificate chain. Check the order of certificates.", gse);
         }
     }
 
+    private List<X509Certificate> loadCertificateChain(KeyStore keyStore, String keyAlias) throws GeneralSecurityException {
+        List<X509Certificate> chain = Optional.ofNullable(keyStore.getCertificateChain(keyAlias))
+                .map(certificates -> Arrays.stream(certificates)
+                        .map(X509Certificate.class::cast)
+                        .collect(Collectors.toList()))
+                .orElseGet(Collections::emptyList);
+
+        validateCertificateChain(chain);
+
+        return chain;
+    }
+
+    /**
+     * <p>Validates the giving certificate chain represented by {@code certificates}. If the list of certificates is empty
+     * or does not have at least 2 certificates (end-user certificate plus intermediary/root CAs) this method does nothing.
+     *
+     * <p>It should not be possible to import to keystores invalid chains though. So this is just an additional check
+     * that we can reuse later for other purposes when the cert chain is also provided manually, in PEM.
+     *
+     * @param certificates
+     */
+    private void validateCertificateChain(List<X509Certificate> certificates) throws GeneralSecurityException {
+        if (certificates == null || certificates.isEmpty()) {
+            return;
+        }
+
+        Set<TrustAnchor> anchors = new HashSet<>();
+
+        // consider the last certificate in the chain as the most trusted cert
+        anchors.add(new TrustAnchor(certificates.get(certificates.size() - 1), null));
+
+        PKIXParameters params = new PKIXParameters(anchors);
+
+        params.setRevocationEnabled(false);
+
+        CertPath certPath = CertificateFactory.getInstance("X.509").generateCertPath(certificates);
+        CertPathValidator validator = CertPathValidator.getInstance(CertPathValidator.getDefaultType());
+
+        validator.validate(certPath, params);
+    }
 }

services/src/main/java/org/keycloak/protocol/oidc/OIDCLoginProtocolService.java

@@ -17,6 +17,10 @@
 
 package org.keycloak.protocol.oidc;
 
+import java.security.cert.X509Certificate;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
 import org.jboss.logging.Logger;
 import org.jboss.resteasy.annotations.cache.NoCache;
 import org.jboss.resteasy.spi.HttpRequest;
@@ -226,8 +230,11 @@ public class OIDCLoginProtocolService {
                 .filter(k -> k.getStatus().isEnabled() && Objects.equals(k.getUse(), KeyUse.SIG) && k.getPublicKey() != null)
                 .map(k -> {
                     JWKBuilder b = JWKBuilder.create().kid(k.getKid()).algorithm(k.getAlgorithm());
+                    List<X509Certificate> certificates = Optional.ofNullable(k.getCertificateChain())
+                        .filter(certs -> !certs.isEmpty())
+                        .orElseGet(() -> Collections.singletonList(k.getCertificate()));
                     if (k.getType().equals(KeyType.RSA)) {
-                        return b.rsa(k.getPublicKey(), k.getCertificate());
+                        return b.rsa(k.getPublicKey(), certificates);
                     } else if (k.getType().equals(KeyType.EC)) {
                         return b.ec(k.getPublicKey());
                     }