added intentbased pg

src/main/java/com/billpaymentservice/bbps/util/EncryptionUtil.java

@@ -0,0 +1,64 @@
+package com.billpaymentservice.bbps.util;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+@Component
+public class EncryptionUtil {
+    private static final Logger LOGGER = LoggerFactory.getLogger(EncryptionUtil.class);
+
+    /**
+     * Encrypts plaintext using AES/CBC/PKCS5Padding.
+     * If the provided key length is not 16/24/32 bytes it will be adjusted to 16 bytes (padded/truncated).
+     * NOTE: This follows the algorithm snippet provided by the user but pads/truncates the key to avoid
+     * common runtime errors when key lengths are incorrect.
+     */
+    public String encryptMData(String plaintext, String encryptKey) {
+        try {
+            // Ensure key length is 16 bytes (AES-128). If callers provide a longer key this will truncate.
+            byte[] keyBytes = normalizeKey(encryptKey);
+            SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
+            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
+
+            byte[] ivBytes = cipher.getParameters().getParameterSpec(IvParameterSpec.class).getIV();
+            byte[] encryptedData = cipher.doFinal(plaintext.getBytes(StandardCharsets.UTF_8));
+
+            byte[] combinedBytes = new byte[ivBytes.length + encryptedData.length];
+            System.arraycopy(ivBytes, 0, combinedBytes, 0, ivBytes.length);
+            System.arraycopy(encryptedData, 0, combinedBytes, ivBytes.length, encryptedData.length);
+            return Base64.getEncoder().encodeToString(combinedBytes);
+        } catch (Exception e) {
+            LOGGER.error("Exception in encrypt() : encryptMData- {} : Message- {}", encryptKey, e.getMessage());
+        }
+        return null;
+    }
+
+    private byte[] normalizeKey(String encryptKey) {
+        if (encryptKey == null) {
+            encryptKey = "";
+        }
+        byte[] bytes = encryptKey.getBytes(StandardCharsets.UTF_8);
+        int targetLen = 16; // AES-128
+        if (bytes.length == targetLen || bytes.length == 24 || bytes.length == 32) {
+            return bytes;
+        }
+        byte[] normalized = new byte[targetLen];
+        for (int i = 0; i < targetLen; i++) {
+            if (i < bytes.length) {
+                normalized[i] = bytes[i];
+            } else {
+                normalized[i] = 0; // pad with zeros
+            }
+        }
+        return normalized;
+    }
+}