Question 80034 in Flutter Question posted in
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how do i decrypt the encrypted string from firebase – Flutter

I have successfully encrypted the data and store it in the firebase as a string value, how do i retrieve the string and turn it into var type and allow it to be decrypt ?

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:encrypt/encrypt.dart' as encrypt;
import 'package:hupcarwashcustomer/validation.dart';
import '../../user_model/encrypt_data.dart';
import '../../user_model/payment.dart';

class createPayment extends StatefulWidget {
  final String name;
  createPayment({required this.name});
  @override
  State<createPayment> createState() => _createPaymentState();
}

class _createPaymentState extends State<createPayment> {
  TextEditingController cardNameController = TextEditingController();
  TextEditingController cvvController = TextEditingController();
  TextEditingController cardNumController = TextEditingController();
  TextEditingController expController = TextEditingController();

  void dispose() {
    cardNameController.dispose();
    cvvController.dispose();
    cardNumController.dispose();
    expController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
        child: Scaffold(
          appBar: AppBar(title: Text('Payment Form'),),
          body: Padding(
            padding: const EdgeInsets.all(8.0),
            child: ListView(
              children: [
                Text(widget.name.toString()),
                const SizedBox(
                  height: 10,
                ),
                TextFormField(
                  controller: cardNameController,
                  decoration: const InputDecoration(border: OutlineInputBorder(), hintText: "Card Name"),
                ),
                const SizedBox(
                  height: 10,
                ),
                TextFormField(
                  controller: cardNumController,
                  decoration: const InputDecoration(border: OutlineInputBorder(), hintText: "Card Num"),
                ),
                const SizedBox(
                  height: 10,
                ),
                TextFormField(
                  controller: cvvController,
                  decoration: const InputDecoration(border: OutlineInputBorder(), hintText: "CVV"),
                ),
                const SizedBox(
                  height: 10,
                ),
                TextFormField(
                  controller: expController,
                  decoration: const InputDecoration(border: OutlineInputBorder(), hintText: "Exp Month/Year"),
                ),
                const SizedBox(
                  height: 10,
                ),
                ElevatedButton(onPressed: () async {
                  var encryptCardNum, encryptCVV, encryptExp;


                  encryptCardNum = MyEncryptionDecryption.encryptFernet(cardNumController.text);
                  encryptCVV = MyEncryptionDecryption.encryptFernet(cvvController.text);
                  encryptExp = MyEncryptionDecryption.encryptFernet(expController.text);

                  createPayment(payment(cardName: cardNameController.text,
                      cardNum: encryptCardNum.base64, name: widget.name.toString(),
                      cvv: encryptCVV.base64, exp: encryptExp.base64, id:''), widget.name.toString());

                  ScaffoldMessenger.of(context).showSnackBar(const SnackBar(
                      content: Text('Payment details have been successfully saved')));
                  Navigator.pop(context);
                }
                    ,child: const Text('Proceed')),
              ],
            ),
          ),
        )
    );
  }
  Future<void> createPayment(payment pay, String id) async{
    String primarykey = '';
    final userCollection = FirebaseFirestore.instance.collection("Payment").doc();
    primarykey = userCollection.id;
    final newPayment = payment(
      id: primarykey,
        name: pay.name,
        cardName: pay.cardName,
        cardNum: pay.cardNum,
        cvv: pay.cvv,
        exp: pay.exp
    ).toJson();

    try {
      await userCollection.set(newPayment);
    } catch (e) {
      print("some error occured $e");
    }
  }
}



import 'package:encrypt/encrypt.dart' as encrypt;

class MyEncryptionDecryption {
  // For Fernet Encryption/Decryption
  static final keyFernet = encrypt.Key.fromUtf8('my32lengthsupersecretnooneknows1');
  // if you need to use the ttl feature, you'll need to use APIs in the algorithm itself
  static final fernet = encrypt.Fernet(keyFernet);
  static final encrypterFernet = encrypt.Encrypter(fernet);

  static encryptFernet(text) {
    final encrypted = encrypterFernet.encrypt(text);
    return encrypted;
  }

  static decryptFernet(text) {
    return encrypterFernet.decrypt(text);
  }
}


//this part is to retrieve from firebase string and pass to decryption method
final service = userData[index];
                                final cardNum = service.cardNum;
                                var finalCardNum = MyEncryptionDecryption.decryptFernet(cardNum);

I have shared 2 of my files here, i hope someone can guide me, because if i pass the string value into the decrypt method, i will get error like Encrypt does not accept String value, the image i share is the image of firebase data
enter image description here

Tags:

2

Answers


  1. 0

    The package you are trying to use is : https://pub.dev/packages/encrypt, in which the decrypt method does not take String as a parameter, instead you need to send the encrypted data in the decrypt method to be able to extract the text from it. For this scenario you can either cast the coming string by writing:

    final service = userData[index];
var cardNum = service.cardNum as Encrypted;

    And then try sending this to the decrypt method in your MyEncryptionDecryption class.

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  2. 0

    First change your MyEncryptionDecryption class to this:

    class MyEncryptionDecryption {
  static final keyFernet =
      encrypt.Key.fromUtf8('my32lengthsupersecretnooneknows1');

  static final fernet = encrypt.Fernet(keyFernet);
  static final encrypterFernet = encrypt.Encrypter(fernet);

  static encrypt.Encrypted encryptFernet(text) {
    final encrypted = encrypterFernet.encrypt(text);
    return encrypted;
  }

  static String decryptFernet(encrypt.Encrypted encrypted) {
    return encrypterFernet.decrypt(encrypted);
  }
}

    then for encrypt try this:

    encypted = MyEncryptionDecryption.encryptFernet('hi');

    and send encypted!.base64 to your firebase. Then for decrypt try this:

    var result = MyEncryptionDecryption.decryptFernet(encrypt.Encrypted.fromBase64(encoded!));

print("result = $result");// hi

    encoded is the string you get from firebase.

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