updated decryption to generate cik and cek based off of key derivation

openid-connect-common/src/main/java/org/mitre/jwt/encryption/AbstractJweDecrypter.java

@@ -1,5 +1,6 @@
 package org.mitre.jwt.encryption;
 
+import java.security.MessageDigest;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 
@@ -9,6 +10,8 @@ public abstract class AbstractJweDecrypter implements JwtDecrypter {
 	
 	private PublicKey publicKey;
 	
+	public MessageDigest md;
+	
 	public PrivateKey getPrivateKey() {
 		return privateKey;
 	}
@@ -24,4 +27,46 @@ public abstract class AbstractJweDecrypter implements JwtDecrypter {
 	public void setPublicKey(PublicKey publicKey) {
 		this.publicKey = publicKey;
 	}
+	
+	public byte[] generateContentKey(byte[] cmk, int keyDataLen, byte[] type) {
+
+		long MAX_HASH_INPUTLEN = Long.MAX_VALUE;
+		long UNSIGNED_INT_MAX_VALUE = 4294967395L;
+
+		keyDataLen = keyDataLen / 8;
+        byte[] key = new byte[keyDataLen];
+        int hashLen = md.getDigestLength();
+        int reps = keyDataLen / hashLen;
+        if (reps > UNSIGNED_INT_MAX_VALUE) {
+            throw new IllegalArgumentException("Key derivation failed");
+        }
+        int counter = 1;
+        byte[] counterInBytes = intToFourBytes(counter);
+        if ((counterInBytes.length + cmk.length + type.length) * 8 > MAX_HASH_INPUTLEN) {
+            throw new IllegalArgumentException("Key derivation failed");
+        }
+        for (int i = 0; i <= reps; i++) {
+            md.reset();
+            md.update(intToFourBytes(i + 1));
+            md.update(cmk);
+            md.update(type);
+            byte[] hash = md.digest();
+            if (i < reps) {
+                System.arraycopy(hash, 0, key, hashLen * i, hashLen);
+            } else {
+                System.arraycopy(hash, 0, key, hashLen * i, keyDataLen % hashLen);
+            }
+        }
+        return key;
+    
+	}
+	
+    public byte[] intToFourBytes(int i) {
+        byte[] res = new byte[4];
+        res[0] = (byte) (i >>> 24);
+        res[1] = (byte) ((i >>> 16) & 0xFF);
+        res[2] = (byte) ((i >>> 8) & 0xFF);
+        res[3] = (byte) (i & 0xFF);
+        return res;
+    }
 }

openid-connect-common/src/main/java/org/mitre/jwt/encryption/JwtAlgorithm.java

@@ -6,15 +6,18 @@ public enum JwtAlgorithm {
 	
 	//TODO:Fill in values for each standard name
 	// RSA
-	RSA1_5(""), 
+	RSA1_5("RSA"), 
-	RSA_OAEP(""), 
+	RSA_OAEP("RSA"), 
 	//EC
-	ECDH_ES(""),
+	ECDH_ES("EC"),
 	//AES
-	A128KW(""),
+	A128KW("AES"),
-	A256KW(""),
+	A256KW("AES"),
-	A128GCM(""),
+	A128CBC("AES"),
-	A256GCM("");
+	A256CBC("AES"),
+	A128GCM("AES"),
+	A256GCM("AES");
+	
 	
 	
 	/**

openid-connect-common/src/main/java/org/mitre/jwt/encryption/JwtDecrypter.java

@@ -1,14 +1,12 @@
 package org.mitre.jwt.encryption;
 
-import java.security.Key;
-
 import org.mitre.jwe.model.Jwe;
 
 public interface JwtDecrypter {
 	
 	public Jwe decrypt(String encryptedJwe);
 	
-	public String decryptCipherText(Jwe jwe, Key cek);
+	public byte[] decryptCipherText(Jwe jwe, byte[] cek);
 	
 	public byte[] decryptEncryptionKey(Jwe jwe);
 	

openid-connect-common/src/main/java/org/mitre/jwt/encryption/impl/RsaDecrypter.java

@@ -1,20 +1,17 @@
 package org.mitre.jwt.encryption.impl;
 
 import java.security.InvalidKeyException;
-import java.security.Key;
-import java.security.KeyPair;
-import java.security.KeyPairGenerator;
 import java.security.NoSuchAlgorithmException;
-import java.security.PrivateKey;
-import java.security.PublicKey;
 
 import javax.crypto.BadPaddingException;
 import javax.crypto.Cipher;
 import javax.crypto.IllegalBlockSizeException;
 import javax.crypto.NoSuchPaddingException;
+import javax.crypto.spec.SecretKeySpec;
 
 import org.mitre.jwe.model.Jwe;
 import org.mitre.jwt.encryption.AbstractJweDecrypter;
+import org.mitre.jwt.encryption.AlgorithmLength;
 import org.mitre.jwt.signer.impl.HmacSigner;
 
 
@@ -32,28 +29,22 @@ public class RsaDecrypter extends AbstractJweDecrypter {
 		String alg = jwe.getHeader().getAlgorithm();
 		if(alg.equals("RS256") || alg.equals("RS384") || alg.equals("RS512")) {
 			
-			PrivateKey contentEncryptionKey = null;
+			//decrypt to get cmk to be used for cek and cik
-			PublicKey contentIntegrityKey = null;
-			
-			try {
-				
-				KeyPairGenerator keyGen = KeyPairGenerator.getInstance(jwe.getHeader().getKeyDerivationFunction());
-				KeyPair keyPair = keyGen.genKeyPair();
-				contentEncryptionKey = keyPair.getPrivate();
-				contentIntegrityKey = keyPair.getPublic();
-				
-			} catch (NoSuchAlgorithmException e1) {
-				// TODO Auto-generated catch block
-				e1.printStackTrace();
-			}
-			
-			jwe.setCiphertext(decryptCipherText(jwe, contentEncryptionKey).getBytes());
 			jwe.setEncryptedKey(decryptEncryptionKey(jwe));
 			
+			//generation of cek and cik
+			String algorithmLength = AlgorithmLength.getByName(jwe.getHeader().getEncryptionMethod()).getStandardName();
+			int keyLength = Integer.parseInt(algorithmLength);
+			byte[] contentEncryptionKey = generateContentKey(jwe.getEncryptedKey(), keyLength, new String("Encryption").getBytes());
+			byte[] contentIntegrityKey = generateContentKey(jwe.getEncryptedKey(), keyLength, new String("Integrity").getBytes());
+			
+			//decrypt ciphertext to get claims
+			jwe.setCiphertext(decryptCipherText(jwe, contentEncryptionKey));
+			
 			//generate signature for decrypted signature base in order to verify that decryption worked
 			String signature = null;
 			try {
-				HmacSigner hmacSigner = new HmacSigner(contentIntegrityKey.getEncoded());
+				HmacSigner hmacSigner = new HmacSigner(contentIntegrityKey);
 				signature = hmacSigner.generateSignature(jwe.getSignatureBase());
 			} catch (NoSuchAlgorithmException e) {
 				// TODO Auto-generated catch block
@@ -76,15 +67,14 @@ public class RsaDecrypter extends AbstractJweDecrypter {
 	}
 
 	@Override
-	public String decryptCipherText(Jwe jwe, Key cek) {
+	public byte[] decryptCipherText(Jwe jwe, byte[] cek) {
 		Cipher cipher;
-		String clearTextString = null;
+		byte[] clearText = null;
 		try {
 			
 			cipher = Cipher.getInstance("RSA");
-			cipher.init(Cipher.DECRYPT_MODE, cek);
+			cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(cek, "RSA"));
-			byte[] clearText = cipher.doFinal(jwe.getCiphertext());
+			clearText = cipher.doFinal(jwe.getCiphertext());
-			clearTextString = new String(clearText);
 			
 		} catch (NoSuchAlgorithmException e) {
 			// TODO Auto-generated catch block
@@ -103,7 +93,7 @@ public class RsaDecrypter extends AbstractJweDecrypter {
 			e.printStackTrace();
 		}
 		
-		return clearTextString;
+		return clearText;
 		
 	}
 

openid-connect-common/src/main/java/org/mitre/jwt/encryption/impl/RsaEncrypter.java

@@ -115,9 +115,9 @@ public class RsaEncrypter extends AbstractJweEncrypter {
 		
 		Cipher cipher;
 		try {
-			cipher = Cipher.getInstance(JwtAlgorithm.getByName(jwe.getHeader().getAlgorithm()).getStandardName());
+			cipher = Cipher.getInstance(JwtAlgorithm.getByName(jwe.getHeader().getEncryptionMethod()).getStandardName());
 			
-			cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(contentEncryptionKey, 0, contentEncryptionKey.length, "RSA"));
+			cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(contentEncryptionKey, "RSA"));
 			cipherText = cipher.doFinal(jwe.getClaims().toString().getBytes());
 			
 		} catch (NoSuchAlgorithmException e) {