working web based and intent

src/main/java/com/billpaymentservice/bbps/controller/PaymentController.java

@@ -59,22 +59,7 @@ public class PaymentController {
 	}
 	
 	
-	@PostMapping(value="/callback/paymentIntiate", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
-    public ResponseEntity<ResponseModel> handleBillValidateCallback(@RequestBody TransactionStatusResponse transactionStatusResponse) {
-		ResponseModel genralResp=paymentService.handlePaymentIntiateCallback(transactionStatusResponse);
-		// Return a response indicating successful receipt
-		return ResponseEntity.ok(genralResp);
-	}
 	
-	@PostMapping(value = "/startPayment", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
-    public ResponseEntity<ResponseModel> startPayment(@Validated @RequestBody PaymentStartUserRequest paymentStartUserRequest) {
-        if (this.paymentStartService == null) {
-            // Defensive: if bean not injected, return failure
-            return ResponseEntity.badRequest().body(new ResponseModel("PaymentStartService not available", "FAILED", 400, null));
-        }
-        ResponseModel response = paymentStartService.startPayment(paymentStartUserRequest);
-        return ResponseEntity.ok(response);
-    }
 	
 	
 }

src/main/java/com/billpaymentservice/bbps/controller/PaymentStartController.java

@@ -1,17 +1,23 @@
 package com.billpaymentservice.bbps.controller;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.validation.annotation.Validated;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
 import com.billpaymentservice.bbps.dto.ResponseModel;
 import com.billpaymentservice.bbps.dto.request.PaymentStartUserRequest;
+import com.billpaymentservice.bbps.dto.request.CallbackRequest;
 import com.billpaymentservice.bbps.service.PaymentStartService;
 
 @RestController
+@RequestMapping("/payment")
 public class PaymentStartController {
 	private final PaymentStartService paymentStartService;
 
@@ -20,12 +26,28 @@ public class PaymentStartController {
 	}
 	
 	@PostMapping(value = "/startWebPayment", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
-    public ResponseEntity<ResponseModel> startPayment(@Validated @RequestBody PaymentStartUserRequest paymentStartUserRequest) {
+    public ResponseEntity<ResponseModel> startWebPayment(@Validated @RequestBody PaymentStartUserRequest paymentStartUserRequest) {
+      
+        ResponseModel response = paymentStartService.startWebPayment(paymentStartUserRequest);
+        return ResponseEntity.ok(response);
+    }
+
+	@PostMapping(value = "/callback/startPayment", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
+	public ResponseEntity<Map<String, String>> handleCallback(@RequestBody CallbackRequest callbackRequest) {
+		ResponseModel resp = paymentStartService.handleStartCallback(callbackRequest);
+		Map<String, String> result = new HashMap<>();
+		// Use the status field from ResponseModel as merchant status code string
+		result.put("status", resp.getStatus());
+		return ResponseEntity.ok(result);
+	}
+	
+	@PostMapping(value = "/startIntentPayment", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
+    public ResponseEntity<ResponseModel> startIntentPayment(@Validated @RequestBody PaymentStartUserRequest paymentStartUserRequest) {
         if (this.paymentStartService == null) {
             // Defensive: if bean not injected, return failure
             return ResponseEntity.badRequest().body(new ResponseModel("PaymentStartService not available", "FAILED", 400, null));
         }
-        ResponseModel response = paymentStartService.startWebPayment(paymentStartUserRequest);
+        ResponseModel response = paymentStartService.startIntentPayment(paymentStartUserRequest);
         return ResponseEntity.ok(response);
     }
-}
+}

src/main/java/com/billpaymentservice/bbps/dto/request/CallbackRequest.java

@@ -0,0 +1,31 @@
+package com.billpaymentservice.bbps.dto.request;
+
+public class CallbackRequest {
+    private String mid;
+    private String data;
+    private String signature;
+
+    public String getMid() {
+        return mid;
+    }
+
+    public void setMid(String mid) {
+        this.mid = mid;
+    }
+
+    public String getData() {
+        return data;
+    }
+
+    public void setData(String data) {
+        this.data = data;
+    }
+
+    public String getSignature() {
+        return signature;
+    }
+
+    public void setSignature(String signature) {
+        this.signature = signature;
+    }
+}

src/main/java/com/billpaymentservice/bbps/entites/PaymentStartRecord.java

@@ -52,4 +52,30 @@ public class PaymentStartRecord {
 
 	@Column(name = "created_on", nullable = false)
 	private String createdOn;
-}
+
+	// New callback-related fields
+	@Column(name = "callback_status")
+	private String callbackStatus;
+
+	@Column(name = "bank_response", columnDefinition = "TEXT")
+	private String bankResponse;
+
+	@Column(name = "signature")
+	private String signature;
+
+	// Store original request body and full response body
+	@Column(name = "request_body", columnDefinition = "TEXT")
+	private String requestBody;
+
+	@Column(name = "response_body", columnDefinition = "TEXT")
+	private String responseBody;
+
+	@Column(name = "response_type")
+	private String responseType; // e.g., "QR", "HTML", "JSON"
+
+	@Column(name = "txn_status")
+	private String txnStatus;
+
+	@Column(name = "callback_received_on")
+	private String callbackReceivedOn;
+}

src/main/java/com/billpaymentservice/bbps/repository/PaymentStartRecordRepository.java

@@ -1,5 +1,7 @@
 package com.billpaymentservice.bbps.repository;
 
+import java.util.Optional;
+
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
 
@@ -7,4 +9,7 @@ import com.billpaymentservice.bbps.entites.PaymentStartRecord;
 
 @Repository
 public interface PaymentStartRecordRepository extends JpaRepository<PaymentStartRecord, Long> {
-}
+    Optional<PaymentStartRecord> findByOrderNo(String orderNo);
+    Optional<PaymentStartRecord> findByTxnId(String txnId);
+    Optional<PaymentStartRecord> findByRequestId(String requestId);
+}

src/main/java/com/billpaymentservice/bbps/service/PaymentService.java

@@ -14,7 +14,6 @@ public interface PaymentService {
 
 	 ResponseModel checkTrasactionStatusByClientReqId(TrasactionStatusByClientReqIdRequest transactionStatusRequest);
 
-	  ResponseModel handlePaymentIntiateCallback(TransactionStatusResponse transactionStatusResponse);
 	
 
 }

src/main/java/com/billpaymentservice/bbps/service/PaymentStartService.java

@@ -2,9 +2,12 @@ package com.billpaymentservice.bbps.service;
 
 import com.billpaymentservice.bbps.dto.ResponseModel;
 import com.billpaymentservice.bbps.dto.request.PaymentStartUserRequest;
+import com.billpaymentservice.bbps.dto.request.CallbackRequest;
 
 public interface PaymentStartService {
-    ResponseModel startPayment(PaymentStartUserRequest request);
-
 	ResponseModel startWebPayment(PaymentStartUserRequest request);
-}
+
+	ResponseModel handleStartCallback(CallbackRequest callbackRequest);
+
+	ResponseModel startIntentPayment(PaymentStartUserRequest paymentStartUserRequest);
+}

src/main/java/com/billpaymentservice/bbps/serviceImpl/PaymentServiceImpl.java

@@ -393,22 +393,7 @@ public class PaymentServiceImpl implements PaymentService {
         }
     }
 
-    @Override
+	
-    public ResponseModel handlePaymentIntiateCallback(TransactionStatusResponse transactionStatusResponse) {
-        String apiName = "HANDLE_PAYMENT_INITIATE_CALLBACK";
-        LOGGER.info("[{}] START | payload={} ", apiName, transactionStatusResponse);
-        LOGGER.info("Received Call Back: {}", transactionStatusResponse);
-        if (transactionStatusResponse.getGeneralResp().getStatusCode().equals(BBPSConstant.SUCCESS_CODE_STR)) {
-            LOGGER.info("Callback indicates SUCCESS with status={}", transactionStatusResponse.getGeneralResp().getStatus());
-        } else {
-            LOGGER.info("Callback indicates FAILURE with status={}", transactionStatusResponse.getGeneralResp().getStatus());
-        }
 
-        LOGGER.info("[{}] END | callback processed", apiName);
+   
-
-        return new ResponseModel(BBPSConstant.CALLBACK_RECEIVED_SUCCESS,
-                BBPSConstant.SUCCESS_CODE_STR,
-                BBPSConstant.HTTP_OK_INT,
-                "");
-    }
 }

src/main/java/com/billpaymentservice/bbps/serviceImpl/PaymentStartServiceImpl.java

@@ -6,6 +6,7 @@ import java.util.Map;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 import java.util.Collections;
+import java.util.Optional;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -17,6 +18,7 @@ import org.springframework.stereotype.Service;
 import com.billpaymentservice.bbps.dto.PaymentStartReturnDto;
 import com.billpaymentservice.bbps.dto.ResponseModel;
 import com.billpaymentservice.bbps.dto.request.PaymentStartUserRequest;
+import com.billpaymentservice.bbps.dto.request.CallbackRequest;
 import com.billpaymentservice.bbps.dto.response.PaymentStartApiResponse;
 import com.billpaymentservice.bbps.dto.response.PaymentStatusResponse;
 import com.billpaymentservice.bbps.dto.sentRequest.PaymentDetailSentRequest;
@@ -36,13 +38,15 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.billpaymentservice.bbps.entites.OutboundTraceLog;
 import com.billpaymentservice.bbps.entites.BharatConnectMaster;
+import com.billpaymentservice.bbps.entites.PaymentStartRecord;
 
 @Service
 public class PaymentStartServiceImpl implements PaymentStartService {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(PaymentStartServiceImpl.class);
 
-    private String uatPaymentUrl="https://uat.godemo.in/api/UATIntegration/uat/payin/paymentrequest";
+    private String uatPaymentUrlweb="https://uat.godemo.in/api/UATIntegration/uat/payin/paymentrequest";
+    private String uatPaymentUrlintent="https://uat.godemo.in/api/UATIntegration/paymentrequest/seamless";
 
     private final PaymentStartRecordRepository paymentStartRecordRepository;
     private final HttpService httpService;
@@ -69,7 +73,7 @@ public class PaymentStartServiceImpl implements PaymentStartService {
         this.bbpsMapperHelper = bbpsMapperHelper;
     }
     @Override
-    public ResponseModel startPayment(PaymentStartUserRequest request) {
+    public ResponseModel startIntentPayment(PaymentStartUserRequest request) {
 
         String requestId = request.getReqId();
         String apiName = "StartPayment";
@@ -97,15 +101,17 @@ public class PaymentStartServiceImpl implements PaymentStartService {
         PaymentRequestPayload finalPayload = new PaymentRequestPayload();
         finalPayload.setMid(BBPSConstant.mid);
         finalPayload.setPayload(encrypted);
+        
 
         String forwardJson = helper.convertObjectToJson(finalPayload);
+        LOGGER.info("Payment Start Request Payload: " + forwardJson);
         OutboundTraceLog outboundLog =
-                helper.createOutboundLog(txnId, requestId, apiName, uatPaymentUrl,
+                helper.createOutboundLog(txnId, requestId, apiName, uatPaymentUrlintent,
                         BBPSConstant.HTTP_POST, forwardJson);
 
         // --- CALL EXTERNAL API ---
         Map<String, String> responseMap =
-                httpService.postRequest(uatPaymentUrl, forwardJson, null);
+                httpService.postRequest(uatPaymentUrlintent, forwardJson, null);
         
         LOGGER.info("Payment Start Response: " + responseMap);
 
@@ -166,19 +172,7 @@ public class PaymentStartServiceImpl implements PaymentStartService {
 
             String message = String.valueOf(payload.getOrDefault("message", top.getOrDefault("message", "")));
 
-            // Map outcome codes according to provided table:
+     
-            // Success: 200
-            // Success without warnings: 205
-            // Warning -> success (fraud accepted): 206 (treat as success)
-            // Warning -> failed (fraud rejected): 207 (treat as failure)
-            // Transaction processing: 198 (treat as pending/processing)
-            // Fail/Exception: 417 -> failure
-            // Failed: 99 -> failure
-            // Rejected by acquirer: 197 -> failure
-            // Declined: 194 -> failure
-            // Auth success but recurring error: 193 -> failure
-            // Warning: 1003 -> warning (non-fatal)
-
             // Handle special cases
             if (outcomeCode == 200 || outcomeCode == 205 || outcomeCode == 206) {
                 // success - build apiResponse from wrapper or direct payload
@@ -238,7 +232,15 @@ public class PaymentStartServiceImpl implements PaymentStartService {
         }
 
         // Save record
-        bbpsMapperHelper.savePaymentStartRecord(request, apiResponse, txnId, orderNo);
+        // Determine response type: QR if qrString present, else JSON
+        String responseType = "JSON";
+        String rawResponse = respBody == null ? "" : respBody;
+        if (apiResponse != null && apiResponse.getResponseData() != null
+                && apiResponse.getResponseData().getQrString() != null
+                && !apiResponse.getResponseData().getQrString().isEmpty()) {
+            responseType = "QR";
+        }
+        bbpsMapperHelper.savePaymentStartRecord(request, apiResponse, txnId, orderNo, requestJson, rawResponse, responseType);
 
         // Prepare DTO
         PaymentStartReturnDto responseData = new PaymentStartReturnDto();
@@ -322,12 +324,12 @@ public class PaymentStartServiceImpl implements PaymentStartService {
 	            "&payload=" + URLEncoder.encode(encrypted, StandardCharsets.UTF_8);
       LOGGER.info("Form Payload: {}", formPayload);
 	    OutboundTraceLog outboundLog =
-	            helper.createOutboundLog(txnId, requestId, apiName, uatPaymentUrl,
+	            helper.createOutboundLog(txnId, requestId, apiName, uatPaymentUrlweb,
 	                    BBPSConstant.HTTP_POST, formPayload);
 
 	    // ----------- CALL API (FORM URL-ENCODED) -----------
 	    Map<String, String> responseMap =
-	            httpService.postFormRequest(uatPaymentUrl, formPayload);
+	            httpService.postFormRequest(uatPaymentUrlweb, formPayload);
 
 	    LOGGER.info("Payment Start Response: {}", responseMap);
 
@@ -350,21 +352,122 @@ public class PaymentStartServiceImpl implements PaymentStartService {
 
 	    // ❗❗ PG RETURNS HTML → NO JSON PARSING REQUIRED
 	    helper.updateInboundLogSuccess(inboundLog, respBody, "200");
+	    
+	    // Save record with HTML (persist original request and HTML response)
+        String responseTypeWeb = "HTML";
+        String rawResponseWeb = respBody == null ? "" : respBody;
+       // bbpsMapperHelper.savePaymentStartRecord(request, null, txnId, orderNo, requestJson, rawResponseWeb, responseTypeWeb);
 
-	    // Save record with HTML (optional)
+        // Return HTML directly in API response
-	  //  bbpsMapperHelper.savePaymentStartHtmlRecord(request, respBody, txnId, orderNo);
+        Map<String, String> result = new HashMap<>();
+        result.put("html", respBody);
 
-	    // Return HTML directly in API response
+        return ResponseModel.builder()
-	    Map<String, String> result = new HashMap<>();
+                .status("SUCCESS")
-	    result.put("html", respBody);
+                .statusCode(200)
-
+                .message("HTML Response Received")
-	    return ResponseModel.builder()
+                .data(result)
-	            .status("SUCCESS")
+                .build();
-	            .statusCode(200)
-	            .message("HTML Response Received")
-	            .data(result)
-	            .build();
 	}
 
+	@Override
+	public ResponseModel handleStartCallback(CallbackRequest callbackRequest) {
+        String apiName = "HANDLE_START_CALLBACK";
+        LOGGER.info("[{}] START | payload={}", apiName, callbackRequest);
 
-}
+        if (callbackRequest == null) {
+            LOGGER.warn("Callback payload is null");
+            return new ResponseModel("Invalid callback", "205", 200, null);
+        }
+
+        String mid = callbackRequest.getMid();
+        String encryptedData = callbackRequest.getData();
+        String signature = callbackRequest.getSignature();
+
+        // Decrypt data
+        String decrypted = encryptionUtil.decryptMData(encryptedData, BBPSConstant.enckey);
+        if (decrypted == null) {
+            LOGGER.error("Failed to decrypt callback payload for mid={}", mid);
+            return new ResponseModel("Decryption failed", "207", 200, null);
+        }
+
+        LOGGER.info("Decrypted callback data: {}", decrypted);
+
+        // Parse decrypted JSON
+        Map<String, Object> payloadMap;
+        try {
+            payloadMap = objectMapper.readValue(decrypted, new TypeReference<Map<String, Object>>(){});
+        } catch (JsonProcessingException e) {
+            LOGGER.error("Failed to parse decrypted callback JSON: {}", e.getMessage(), e);
+            return new ResponseModel("Invalid decrypted JSON", "207", 200, null);
+        }
+
+        String txnId = String.valueOf(payloadMap.getOrDefault("txnId", payloadMap.getOrDefault("txn_id", "")));
+        String orderNo = String.valueOf(payloadMap.getOrDefault("orderNo", payloadMap.getOrDefault("order_no", "")));
+        String txnStatus = String.valueOf(payloadMap.getOrDefault("txnStatus", payloadMap.getOrDefault("txn_status", payloadMap.getOrDefault("status", ""))));
+
+        // Compute checksum: Mid + txnId + orderNo + txnStatus
+        String checksumStr = mid + txnId + orderNo + txnStatus;
+        String computedChecksum = encryptionUtil.getChecksumCRC32(checksumStr);
+
+        boolean signatureMatches = false;
+        if (computedChecksum != null && signature != null) {
+            signatureMatches = computedChecksum.equals(signature) || computedChecksum.equals(String.valueOf(Long.parseLong(signature)));
+        }
+
+        // Find DB record
+        Optional<PaymentStartRecord> recordOpt = Optional.empty();
+        if (orderNo != null && !orderNo.isEmpty()) {
+            recordOpt = paymentStartRecordRepository.findByOrderNo(orderNo);
+        }
+        if (recordOpt.isEmpty() && txnId != null && !txnId.isEmpty()) {
+            recordOpt = paymentStartRecordRepository.findByTxnId(txnId);
+        }
+
+        PaymentStartRecord record = recordOpt.orElse(null);
+        if (record == null) {
+            LOGGER.warn("No PaymentStartRecord found for orderNo={} txnId={}", orderNo, txnId);
+            // still return 205 to acknowledge receipt
+            return new ResponseModel("No matching record", "205", 200, null);
+        }
+
+        // Update record with bank response and signature
+        record.setBankResponse(decrypted);
+        record.setSignature(signature);
+        // update txn status and callback timestamp
+        record.setTxnStatus(txnStatus);
+        record.setCallbackReceivedOn(java.time.LocalDateTime.now().toString());
+
+        String merchantStatus;
+        if (!signatureMatches) {
+            LOGGER.error("Signature mismatch. computed={} provided={}", computedChecksum, signature);
+            record.setCallbackStatus("SIGNATURE_MISMATCH");
+            paymentStartRecordRepository.save(record);
+            merchantStatus = "207"; // treat as rejected/failure
+            LOGGER.info("[{}] END | returning status={}", apiName, merchantStatus);
+            return new ResponseModel("Signature mismatch", merchantStatus, 200, null);
+        }
+
+        // signature ok - decide response based on txnStatus
+        if (txnStatus.equalsIgnoreCase("SUCCESS") || txnStatus.equalsIgnoreCase("SUCCESSFUL") || txnStatus.equalsIgnoreCase("SUCCESSFULL")) {
+            record.setCallbackStatus("SUCCESS");
+            paymentStartRecordRepository.save(record);
+            merchantStatus = "206"; // accepted by merchant
+        } else if (txnStatus.equalsIgnoreCase("FAILED") || txnStatus.equalsIgnoreCase("FAIL")) {
+            record.setCallbackStatus("FAILED");
+            paymentStartRecordRepository.save(record);
+            merchantStatus = "207"; // rejected
+        } else {
+            record.setCallbackStatus("RECEIVED");
+            paymentStartRecordRepository.save(record);
+            merchantStatus = "205"; // generic ack
+        }
+
+        LOGGER.info("Callback processed for orderNo={} txnId={} status={} returning merchantStatus={}", orderNo, txnId, txnStatus, merchantStatus);
+        LOGGER.info("[{}] END", apiName);
+
+        return new ResponseModel("Callback processed", merchantStatus, 200, null);
+    }
+
+
+}

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

@@ -1081,18 +1081,25 @@ public class BillerMapperHelper {
 	}
 
 	public void savePaymentStartRecord(PaymentStartUserRequest request, PaymentStartApiResponse apiResponse,
-			String txnId, String orderNo) {
+			String txnId, String orderNo, String requestJson, String rawResponse, String responseType) {
 		PaymentStartRecord record = new PaymentStartRecord();
 		record.setOrderNo(orderNo);
 		record.setRequestId(request.getReqId());
 		record.setClientMid(request.getMid());
 		record.setClientUserId(request.getClientUserId());
 		record.setInternalTxnId(txnId);
-		record.setAmount(apiResponse.getResponseData().getAmount());
+		if (apiResponse != null && apiResponse.getResponseData() != null) {
-		record.setMid(apiResponse.getResponseData().getMid());
+			record.setAmount(apiResponse.getResponseData().getAmount());
-		record.setTxnId(apiResponse.getResponseData().getTxnId());
+			record.setMid(apiResponse.getResponseData().getMid());
-		record.setQrString(apiResponse.getResponseData().getQrString());
+			record.setTxnId(apiResponse.getResponseData().getTxnId());
-		record.setCreatedOn(apiResponse.getResponseData().getCreatedOn());
+			record.setQrString(apiResponse.getResponseData().getQrString());
+			record.setCreatedOn(apiResponse.getResponseData().getCreatedOn());
+		}
+
+		// store the original request body and raw response
+		record.setRequestBody(requestJson);
+		record.setResponseBody(rawResponse);
+		record.setResponseType(responseType);
 
 		paymentStartRecordRepository.save(record);
 	}

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

@@ -1,7 +1,11 @@
 package com.billpaymentservice.bbps.util;
 
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.Base64;
+import java.util.zip.CRC32;
 
 import javax.crypto.Cipher;
 import javax.crypto.spec.IvParameterSpec;
@@ -18,12 +22,9 @@ public class EncryptionUtil {
     /**
      * 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");
@@ -61,4 +62,56 @@ public class EncryptionUtil {
         }
         return normalized;
     }
-}
+
+    /**
+     * Decrypts data encrypted by encryptMData: Base64(iv + ciphertext) with AES/CBC/PKCS5Padding
+     */
+    public String decryptMData(String base64Payload, String encryptKey) {
+        if (base64Payload == null) return null;
+        try {
+            byte[] combined = Base64.getDecoder().decode(base64Payload);
+            // IV is first 16 bytes for AES
+            if (combined.length < 16) {
+                LOGGER.warn("Encrypted payload too short to contain IV");
+                return null;
+            }
+            byte[] iv = new byte[16];
+            System.arraycopy(combined, 0, iv, 0, 16);
+            byte[] cipherText = new byte[combined.length - 16];
+            System.arraycopy(combined, 16, cipherText, 0, cipherText.length);
+
+            byte[] keyBytes = normalizeKey(encryptKey);
+            SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
+
+            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+            cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, new IvParameterSpec(iv));
+
+            byte[] plain = cipher.doFinal(cipherText);
+            return new String(plain, StandardCharsets.UTF_8);
+        } catch (Exception ex) {
+            LOGGER.error("Error decrypting payload: {}", ex.getMessage());
+            return null;
+        }
+    }
+
+    /**
+     * Compute CRC32 checksum value for the provided input string and return the numeric value as String
+     */
+    public String getChecksumCRC32(String input) {
+        if (input == null) input = "";
+        try (InputStream is = new ByteArrayInputStream(input.getBytes(StandardCharsets.UTF_8))) {
+            CRC32 crc = new CRC32();
+            byte[] buffer = new byte[1024];
+            int len;
+            while ((len = is.read(buffer)) != -1) {
+                crc.update(buffer, 0, len);
+            }
+            long value = crc.getValue();
+            LOGGER.debug("Computed CRC32: {} for input: {}", value, input);
+            return String.valueOf(value);
+        } catch (IOException e) {
+            LOGGER.error("Error computing CRC32: {}", e.getMessage());
+            return null;
+        }
+    }
+}