BAEL-1371 - Guide to Cipher class (#3150)

* Bean Injection Types

* Bean Injection Types

* Bean Injection Types

* Bean Injection Types -  Added / Fixed tests

* BAEL-1371 Encryptor class

* BAEL-1371 Modified Encryptor class, added encryptor test

* BAEL-1371 Modified Encryptor class, added encryptor test

* BAEL-1371 removed spring core files

* BAEL-1371 Update test, new line for "when" and "then" logic

* BAEL-1371 Fixed tests

* BAEL-1371 cleanup and assertj assertions

core-java/src/main/java/com/baeldung/cipher/Encryptor.java

@@ -0,0 +1,35 @@
+package com.baeldung.cipher;
+
+import javax.crypto.*;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.cert.Certificate;
+
+public class Encryptor {
+
+    public byte[] encryptMessage(byte[] message, byte[] keyBytes) throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
+        byte[] encryptedMessage = cipher.doFinal(message);
+        return encryptedMessage;
+    }
+
+    public byte[] encryptMessage(byte[] message, Certificate publicKeyCertificate) throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
+        cipher.init(Cipher.ENCRYPT_MODE, publicKeyCertificate);
+        byte[] encryptedMessage = cipher.doFinal(message);
+        return encryptedMessage;
+    }
+
+    public byte[] decryptMessage(byte[] encryptedMessage, byte[] keyBytes) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(Cipher.DECRYPT_MODE, secretKey);
+        byte[] clearMessage = cipher.doFinal(encryptedMessage);
+        return clearMessage;
+    }
+
+
+}