Added improvements and decrypt test

Author: lcsjunior

src/main/java/com/thealgorithms/ciphers/XORCipher.java

@@ -2,7 +2,7 @@
 
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
-import java.util.Base64;
+import java.util.HexFormat;
 
 /**
  * A simple implementation of XOR cipher that, given a key, allows to encrypt and decrypt a plaintext.
@@ -17,23 +17,25 @@ public final class XORCipher {
     private XORCipher() {
     }
 
-    private static byte[] xor(final byte[] inputBytes, final byte[] keyBytes) {
+    public static byte[] xor(final byte[] inputBytes, final byte[] keyBytes) {
         byte[] outputBytes = new byte[inputBytes.length];
         for (int i = 0; i < inputBytes.length; ++i) {
             outputBytes[i] = (byte) (inputBytes[i] ^ keyBytes[i % keyBytes.length]);
         }
         return outputBytes;
     }
 
-    public static String encrypt(final String plaintext, final String key) {
-        byte[] plaintextBytes = plaintext.getBytes(CS_DEFAULT);
+    public static String encrypt(final String plainText, final String key) {
+        byte[] plainTextBytes = plainText.getBytes(CS_DEFAULT);
         byte[] keyBytes = key.getBytes(CS_DEFAULT);
-        return Base64.getEncoder().encodeToString(xor(plaintextBytes, keyBytes));
+        byte[] xorResult = xor(plainTextBytes, keyBytes);
+        return HexFormat.of().formatHex(xorResult);
     }
 
-    public static String decrypt(final String cipher, final String key) {
-        byte[] cipherBytes = Base64.getDecoder().decode(cipher);
+    public static String decrypt(final String cipherText, final String key) {
+        byte[] cipherBytes = HexFormat.of().parseHex(cipherText);
         byte[] keyBytes = key.getBytes(CS_DEFAULT);
-        return new String(xor(cipherBytes, keyBytes), CS_DEFAULT);
+        byte[] xorResult = xor(cipherBytes, keyBytes);
+        return new String(xorResult, CS_DEFAULT);
     }
 }

src/test/java/com/thealgorithms/ciphers/XORCipherTest.java

@@ -7,13 +7,28 @@
 class XORCipherTest {
 
     @Test
-    void shouldEncryptAndDecryptTest() {
+    void xorEncryptTest() {
         // given
         String plaintext = "My t&xt th@t will be ençrypted...";
         String key = "My ç&cret key!";
+
         // when
         String cipherText = XORCipher.encrypt(plaintext, key);
+
+        // then
+        assertEquals("000000b7815e1752111c601f450e48211500a1c206061ca6d35212150d4429570eed", cipherText);
+    }
+
+    @Test
+    void xorDecryptTest() {
+        // given
+        String cipherText = "000000b7815e1752111c601f450e48211500a1c206061ca6d35212150d4429570eed";
+        String key = "My ç&cret key!";
+
+        // when
+        String plainText = XORCipher.decrypt(cipherText, key);
+
         // then
-        assertEquals(XORCipher.decrypt(cipherText, key), plaintext);
+        assertEquals("My t&xt th@t will be ençrypted...", plainText);
     }
 }