aes_cipher_with_iv.dart

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:encrypt/encrypt.dart' as encrypt;
import 'package:crypto/crypto.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) => MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: MyScaffold(),
      );
}

class MyScaffold extends StatelessWidget {
  @override
  Widget build(BuildContext context) => Scaffold(
      appBar: AppBar(
        title: const Text('My App'),
      ),
      body: body(context));

  Widget body(BuildContext context) {

    final password = 'passwordpass';
    final plainText = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit';

    var encrypted = encryptString(sourcePlainText: plainText, password: password);
    print('encrypted: ${encrypted.b64Cipher}');
    print('iv: ${encrypted.b64IV}');

    var decrypted = encrypted.decrypt(password);

    print('decrypted: $decrypted');

    var civ = CipherWithIV(
      b64Cipher: 'HcW/1CqTA+ZagAsRu8OFtiXLaopteUdQJAQQum46Bq8Mho4d/wuCqXxHmyMY5RiMHPvrlKq0rNlUCFM0Ek9wvQ==',
      b64IV: 'al1YZpr2w7InNndD6DDfRw==',
    );
    var decrypted2 = civ.decrypt('passwordpass');

    return Text(decrypted2);
  }

}

class CipherWithIV{
  final String b64Cipher;
  final String b64IV;

  CipherWithIV({this.b64Cipher, this.b64IV});

  String decrypt(String password) {
    final iv = encrypt.IV.fromBase64(b64IV);
    final encrypter = getEncrypter(password);
    return encrypter.decrypt(
        encrypt.Encrypted.fromBase64(b64Cipher), iv: iv);
  }

  static encrypt.Encrypter getEncrypter(String password) {
    final hashedPassword = sha256.convert(utf8.encode(password));
    final key = encrypt.Key(hashedPassword.bytes);
    return encrypt.Encrypter(
        encrypt.AES(key, mode: encrypt.AESMode.cbc));
  }

}

CipherWithIV encryptString({String sourcePlainText, String password}) {
  final iv = encrypt.IV.fromSecureRandom(16);
  final encrypter = CipherWithIV.getEncrypter(password);
  final encrypted = encrypter.encrypt(
      sourcePlainText, iv: iv);
  return CipherWithIV(
    b64Cipher: encrypted.base64,
    b64IV: iv.base64
  );
}

aes_cipher_with_iv.py

import base64

from Crypto import Random
from Crypto.Cipher import AES
from Crypto.Hash import SHA256


def pkcs7(source):
    return source + chr(16 - len(source) % 16) * (16 - len(source) % 16)


def unpad(ct):
    return ct[:-ct[-1]]


class CipherWithIV():
    def __init__(self, *, b64cipher: str, b64iv: str):
        self.b64cipher = b64cipher
        self.b64iv = b64iv

    def decrypt(self, password: str) -> str:
        encryper = get_encrypter(password, base64.b64decode(
            self.b64iv.encode('utf-8')))
        return unpad(
            encryper.decrypt(base64.b64decode(
                self.b64cipher.encode('utf-8')))).decode('utf-8')


def get_encrypter(password: str, iv: bytes):
    sha = SHA256.new()
    sha.update(password.encode())
    hashed_password = sha.digest()
    return AES.new(hashed_password, AES.MODE_CBC, iv)


def encrypt_string(*, source_plain_text: str, password: str):
    iv = Random.new().read(AES.block_size)
    encrypter = get_encrypter(password, iv)
    return CipherWithIV(
        b64cipher=base64.b64encode(
            encrypter.encrypt(pkcs7(source_plain_text))).decode('utf-8'),
        b64iv=base64.b64encode(iv).decode('utf-8')
    )


def main():
    password = 'passwordpass'
    plain_text = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit'

    cipheriv = encrypt_string(source_plain_text=plain_text, password=password)

    print(f'cipher: {cipheriv.b64cipher}')
    print(f'iv: {cipheriv.b64iv}')

    decrypted = cipheriv.decrypt(password)
    print(f'decrypted: {decrypted}')

    cipheriv2 = CipherWithIV(
        b64cipher='/wcD/RVapLkpul2eQCDusPrJsF15ZWpkzkGRRYdQvyzAEZeJfxVyVqs1qt/w1Zf70KM6/1j0O+wgEuEXzyYSkw==',
        b64iv='sdE5p0jzxEADLsssB1Hj1g=='
    )
    decrypted2 = cipheriv2.decrypt('passwordpass')
    print(f'decrypted2: {decrypted2}')


if __name__ == '__main__':
    main()