C# Encrypt data AES

Question

Is there a way to encrypt data with AES? I'd love to use at least 128 Bits for the encryption Key.

I tried with AES default class provided by Microsoft but I can't do a lot... I can't set the Key Lenght.

Is there another Class that I can use?

Answer 1

Yes. You can use the code listed at http://www.codeproject.com/Articles/769741/Csharp-AES-bits-Encryption-Library-with-Salt

You Can Use RIJNDAEL:

First you need to include using System.Security.Cryptography;

public byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
    {
        byte[] encryptedBytes = null;

        // Set your salt here, change it to meet your flavor:
        // The salt bytes must be at least 8 bytes.
        byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

        using (MemoryStream ms = new MemoryStream())
        {
            using (RijndaelManaged AES = new RijndaelManaged())
            {
                AES.KeySize = 256;
                AES.BlockSize = 128;

                var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                AES.Key = key.GetBytes(AES.KeySize / 8);
                AES.IV = key.GetBytes(AES.BlockSize / 8);

                AES.Mode = CipherMode.CBC;

                using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
                    cs.Close();
                }
                encryptedBytes = ms.ToArray();
            }
        }

        return encryptedBytes;
    }

    public byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
    {
        byte[] decryptedBytes = null;

        // Set your salt here, change it to meet your flavor:
        // The salt bytes must be at least 8 bytes.
        byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

        using (MemoryStream ms = new MemoryStream())
        {
            using (RijndaelManaged AES = new RijndaelManaged())
            {
                AES.KeySize = 256;
                AES.BlockSize = 128;

                var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
                AES.Key = key.GetBytes(AES.KeySize / 8);
                AES.IV = key.GetBytes(AES.BlockSize / 8);

                AES.Mode = CipherMode.CBC;

                using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
                    cs.Close();
                }
                decryptedBytes = ms.ToArray();
            }
        }

        return decryptedBytes;
    }


public void EncryptFile(string filename, string outfilename, string psw)
        {
            string file = filename;
            string password = psw;

            byte[] bytesToBeEncrypted = File.ReadAllBytes(file); //read bytes to encrypt them 
            byte[] passwordBytes = Encoding.UTF8.GetBytes(password); //read with UTF8 encoding the password.
            passwordBytes = SHA256.Create().ComputeHash(passwordBytes); //hash the psw

            byte[] bytesEncrypted = AES_Encrypt(bytesToBeEncrypted, passwordBytes);

            string fileEncrypted = outfilename;

            File.WriteAllBytes(fileEncrypted, bytesEncrypted);
        }
        public void DecryptFile(string filename, string outfilename, string psw)
        {
            string fileEncrypted = filename;
            string password = psw;

            byte[] bytesToBeDecrypted = File.ReadAllBytes(fileEncrypted);
            byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
            passwordBytes = SHA256.Create().ComputeHash(passwordBytes);

            byte[] bytesDecrypted = AES_Decrypt(bytesToBeDecrypted, passwordBytes);

            string file = outfilename;
            File.WriteAllBytes(file, bytesDecrypted);
        }