refactor: move the base64UrlEncode out of JweObject (#37)

* add base64url encoding in encoding utils

base64url encoding with no padding

* refactor: remove base64UrlEncode from JweObject

remove base64UrlEncode from JweObject and using same function from
EncodingUtils.

Author: geekypandey

src/main/java/com/mastercard/developer/encryption/jwe/JweObject.java

@@ -8,6 +8,7 @@
 import com.mastercard.developer.encryption.rsa.RSA;
 import com.mastercard.developer.json.JsonEngine;
 import com.mastercard.developer.utils.ByteUtils;
+import com.mastercard.developer.utils.EncodingUtils;
 
 import javax.crypto.Cipher;
 import javax.crypto.spec.GCMParameterSpec;
@@ -57,14 +58,14 @@ public String decrypt(JweConfig config) throws EncryptionException, GeneralSecur
     public static String encrypt(JweConfig config, String payload, JweHeader header) throws EncryptionException, GeneralSecurityException {
         SecretKeySpec cek = AESEncryption.generateCek(256);
         byte[] encryptedSecretKeyBytes = RSA.wrapSecretKey(config.getEncryptionCertificate().getPublicKey(), cek, "SHA-256");
-        String encryptedKey = base64UrlEncode(encryptedSecretKeyBytes);
+        String encryptedKey = EncodingUtils.base64UrlEncode(encryptedSecretKeyBytes);
 
         byte[] iv = AESEncryption.generateIv().getIV();
         byte[] payloadBytes = payload.getBytes();
         GCMParameterSpec gcmSpec = new GCMParameterSpec(128, iv);
 
         String headerString = header.toJson();
-        String encodedHeader = base64UrlEncode(headerString.getBytes());
+        String encodedHeader = EncodingUtils.base64UrlEncode(headerString.getBytes());
 
         byte[] aad = encodedHeader.getBytes(StandardCharsets.US_ASCII);
 
@@ -76,7 +77,7 @@ public static String encrypt(JweConfig config, String payload, JweHeader header)
         byte[] cipherText = ByteUtils.subArray(cipherOutput, 0, tagPos);
         byte[] authTag = ByteUtils.subArray(cipherOutput, tagPos, ByteUtils.byteLength(128));
 
-        return serialize(encodedHeader, encryptedKey, base64UrlEncode(iv), base64UrlEncode(cipherText), base64UrlEncode(authTag));
+        return serialize(encodedHeader, encryptedKey, EncodingUtils.base64UrlEncode(iv), EncodingUtils.base64UrlEncode(cipherText), EncodingUtils.base64UrlEncode(authTag));
     }
 
     private static String serialize(String header, String encryptedKey, String iv, String cipherText, String authTag) {
@@ -90,14 +91,6 @@ private static String serialize(String header, String encryptedKey, String iv, S
                 authTag;
     }
 
-    /**
-     * BASE64URL as per https://datatracker.ietf.org/doc/html/rfc7515#appendix-C
-     */
-    private static String base64UrlEncode(byte[] bytes) {
-        return Base64.getUrlEncoder().encodeToString(bytes)
-            .replace("=", ""); // Remove any trailing '='s
-    }
-
     public static JweObject parse(String encryptedPayload, JsonEngine jsonEngine) {
         String[] payloadParts = encryptedPayload.trim()
                                     .split("\\.");

src/main/java/com/mastercard/developer/utils/EncodingUtils.java

@@ -63,4 +63,11 @@ static String base64Encode(byte[] bytes) {
         }
         return Base64.getEncoder().encodeToString(bytes);
     }
+
+    /**
+     * BASE64URL as per https://datatracker.ietf.org/doc/html/rfc7515#appendix-C
+     */
+    public static String base64UrlEncode(byte[] bytes) {
+        return Base64.getUrlEncoder().withoutPadding().encodeToString(bytes);
+    }
 }

src/test/java/com/mastercard/developer/utils/EncodingUtilsTest.java

@@ -67,4 +67,11 @@ public void testBase64Decode() {
     public void testBase64Decode_ShouldThrowIllegalArgumentException_WhenNullValue() {
         EncodingUtils.base64Decode(null);
     }
+
+    @Test
+    public void testBase64UrlEncode() {
+        Assert.assertEquals("AA", EncodingUtils.base64UrlEncode(new byte[1]));
+        Assert.assertEquals("eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkEyNTZHQ00ifQ", EncodingUtils.base64UrlEncode("{\"alg\":\"RSA-OAEP\",\"enc\":\"A256GCM\"}".getBytes()));
+        Assert.assertEquals("bGlnaHQgd29yaw", EncodingUtils.base64UrlEncode("light work".getBytes()));
+    }
 }