An easy way to encrypt and decrypt with a key [duplicate]

Question

I'm looking for an easy way to encrypt and decrypt some data using a fixed key (which will be stored in my configurations) and store the result as string (base16 or hex).

Something like

string myString = "hello world";
string myKey = "k2k3aij3h";
string enc = new Algorithm().Encrypt(myString, myKey);
string dec = new Alrorithm().Decrypt(enc, myKey);

Answer 1

try this

       private const string initVector = "tu89geji340t89u2";

        private const int keysize = 256;

        public static string Encrypt(string Text, string Key)
        {
            byte[] initVectorBytes = Encoding.UTF8.GetBytes(initVector);
            byte[] plainTextBytes = Encoding.UTF8.GetBytes(Text);
            PasswordDeriveBytes password = new PasswordDeriveBytes(Key, null);
            byte[] keyBytes = password.GetBytes(keysize / 8);
            RijndaelManaged symmetricKey = new RijndaelManaged();
            symmetricKey.Mode = CipherMode.CBC;
            ICryptoTransform encryptor = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes);
            MemoryStream memoryStream = new MemoryStream();
            CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write);
            cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
            cryptoStream.FlushFinalBlock();
            byte[] Encrypted = memoryStream.ToArray();
            memoryStream.Close();
            cryptoStream.Close();
            return Convert.ToBase64String(Encrypted);
        }

        public static string Decrypt(string EncryptedText, string Key)
        {
            byte[] initVectorBytes = Encoding.ASCII.GetBytes(initVector);
            byte[] DeEncryptedText = Convert.FromBase64String(EncryptedText);
            PasswordDeriveBytes password = new PasswordDeriveBytes(Key, null);
            byte[] keyBytes = password.GetBytes(keysize / 8);
            RijndaelManaged symmetricKey = new RijndaelManaged();
            symmetricKey.Mode = CipherMode.CBC;
            ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes);
            MemoryStream memoryStream = new MemoryStream(DeEncryptedText);
            CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);
            byte[] plainTextBytes = new byte[DeEncryptedText.Length];
            int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
            memoryStream.Close();
            cryptoStream.Close();
            return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
        }

it's from here