Revert "removed the plain verifer. validating a no-signature is simply handled as a special case in validateSignature(). Also, doing some type safety checks."

This reverts commit c957d59f7c.

openid-connect-common/src/main/java/org/mitre/jwt/signer/PlainVerifier.java

@@ -0,0 +1,96 @@
+/*******************************************************************************
+ * Copyright 2013 The MITRE Corporation 
+ *   and the MIT Kerberos and Internet Trust Consortium
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ ******************************************************************************/
+package org.mitre.jwt.signer;
+
+import java.util.Set;
+
+import com.google.common.collect.Sets;
+import com.nimbusds.jose.DefaultJWSHeaderFilter;
+import com.nimbusds.jose.JOSEException;
+import com.nimbusds.jose.JWSAlgorithm;
+import com.nimbusds.jose.JWSHeaderFilter;
+import com.nimbusds.jose.JWSVerifier;
+import com.nimbusds.jose.PlainHeader;
+import com.nimbusds.jose.ReadOnlyJWSHeader;
+import com.nimbusds.jose.Requirement;
+import com.nimbusds.jose.util.Base64URL;
+import com.nimbusds.jwt.PlainJWT;
+
+/**
+ * Verifier to support "alg:none" JWS signing option (no signature).
+ * 
+ * FIXME: The JWSVerifier interface was never intended to be used with plain JWTs.
+ * Use of the signer/verifier pattern alongside the other JWSSigner/Verifiers will require refactoring.
+ * 
+ * @author wkim
+ *
+ */
+public final class PlainVerifier implements JWSVerifier {
+
+	// the NONE alg constant lives in the Algorithm superclass of JWSAlgorithm, not allowing its use as a JWSAlgorithm object.
+	// redefining the constant here for convenience.
+	private static final JWSAlgorithm NONE = new JWSAlgorithm("none", Requirement.REQUIRED);
+	
+	/**
+	 * The JWS header filter.
+	 */
+	private final DefaultJWSHeaderFilter headerFilter;
+	
+	public PlainVerifier() {
+		
+		headerFilter = new DefaultJWSHeaderFilter(Sets.newHashSet(NONE));
+		
+	}
+
+	
+	@Override
+	public Set<JWSAlgorithm> supportedAlgorithms() {
+		return Sets.newHashSet(NONE); 
+	}
+
+
+	@Override
+	public JWSHeaderFilter getJWSHeaderFilter() {
+		return headerFilter;
+	}
+
+	@Override
+	public boolean verify(ReadOnlyJWSHeader header, byte[] signingInput, Base64URL signature) throws JOSEException {
+		
+		if (header instanceof PlainHeader) {
+			// XXX NOT POSSIBLE--Interface does not allow this.
+			return signature.decode().length == 0;
+			
+		} else { // not a plain (unsigned) JWS
+			
+			throw new JOSEException("Not a plain JWT header.");
+			
+		}
+	}
+	
+	/**
+	 * Verifies that the third signature component of the JWT is null.
+	 * 
+	 * @param jwt
+	 * @return
+	 */
+	public static boolean verify(PlainJWT jwt) {
+		
+		return jwt.getParsedParts()[2] == null;
+	}
+
+}

openid-connect-common/src/main/java/org/mitre/jwt/signer/service/impl/DefaultJwtSigningAndValidationService.java

@@ -28,6 +28,7 @@ import javax.annotation.PostConstruct;
 
 import org.mitre.jose.keystore.JWKSetKeyStore;
 import org.mitre.jwt.signer.PlainSigner;
+import org.mitre.jwt.signer.PlainVerifier;
 import org.mitre.jwt.signer.service.JwtSigningAndValidationService;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -164,7 +165,6 @@ public class DefaultJwtSigningAndValidationService implements JwtSigningAndValid
 	private void buildSignersAndVerifiers() throws NoSuchAlgorithmException, InvalidKeySpecException {
 		
 		signers.put(ALG_NONE, new PlainSigner());
-		// no plain verifier, that is handled as a special case in validateSignature().
 		
 		for (Map.Entry<String, JWK> jwkEntry : keys.entrySet()) {
 
@@ -288,20 +288,17 @@ public class DefaultJwtSigningAndValidationService implements JwtSigningAndValid
 	@Override
 	public boolean validateSignature(JWT jwt) {
 
-		if (getDefaultSignerKeyId().equals(ALG_NONE)) {
+		if (getDefaultSignerKeyId().equals(ALG_NONE) && (jwt instanceof PlainJWT)) {
 			
-			return (jwt instanceof PlainJWT);
+			return PlainVerifier.verify((PlainJWT) jwt);
 			
 		} else { 
 
 			for (JWSVerifier verifier : verifiers.values()) {
-				
 				try {
-					
-					if (jwt instanceof SignedJWT) {
-						return ((SignedJWT) jwt).verify(verifier);
+					if (((SignedJWT) jwt).verify(verifier)) {
+						return true;
 					}
-					
 				} catch (JOSEException e) {
 	
 					logger.error("Failed to validate signature, error was: ", e);