Encrypt, decrypt and generate a key in C# using AES256.

encryption.cs

#region Encryption
/// <summary>
/// Generate a private key
/// From : www.chapleau.info/blog/2011/01/06/usingsimplestringkeywithaes256encryptioninc.html
/// </summary>
private static string GenerateKey(int iKeySize)
{
    RijndaelManaged aesEncryption = new RijndaelManaged();
    aesEncryption.KeySize = iKeySize;
    aesEncryption.BlockSize = 128;
    aesEncryption.Mode = CipherMode.CBC;
    aesEncryption.Padding = PaddingMode.PKCS7;
    aesEncryption.GenerateIV();
    string ivStr = Convert.ToBase64String(aesEncryption.IV);
    aesEncryption.GenerateKey();
    string keyStr = Convert.ToBase64String(aesEncryption.Key);
    string completeKey = ivStr + "," + keyStr;

    return Convert.ToBase64String(ASCIIEncoding.UTF8.GetBytes(completeKey));
}  

/// <summary>
/// Encrypt
/// From : www.chapleau.info/blog/2011/01/06/usingsimplestringkeywithaes256encryptioninc.html
/// </summary>
private static string Encrypt(string iPlainStr, string iCompleteEncodedKey, int iKeySize)
{
    RijndaelManaged aesEncryption = new RijndaelManaged();
    aesEncryption.KeySize = iKeySize;
    aesEncryption.BlockSize = 128;
    aesEncryption.Mode = CipherMode.CBC;
    aesEncryption.Padding = PaddingMode.PKCS7;
    aesEncryption.IV = Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[0]);
    aesEncryption.Key = Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[1]);
    byte[] plainText = ASCIIEncoding.UTF8.GetBytes(iPlainStr);
    ICryptoTransform crypto = aesEncryption.CreateEncryptor();         
    byte[] cipherText = crypto.TransformFinalBlock(plainText, 0, plainText.Length);
    return Convert.ToBase64String(cipherText);
}

/// <summary>
/// Decrypt
/// From : www.chapleau.info/blog/2011/01/06/usingsimplestringkeywithaes256encryptioninc.html
/// </summary>
private static string Decrypt(string iEncryptedText, string iCompleteEncodedKey, int iKeySize)
{
    RijndaelManaged aesEncryption = new RijndaelManaged();
    aesEncryption.KeySize = iKeySize;
    aesEncryption.BlockSize = 128;
    aesEncryption.Mode = CipherMode.CBC;
    aesEncryption.Padding = PaddingMode.PKCS7;
    aesEncryption.IV = Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[0]);
    aesEncryption.Key = Convert.FromBase64String(ASCIIEncoding.UTF8.GetString(Convert.FromBase64String(iCompleteEncodedKey)).Split(',')[1]);
    ICryptoTransform decrypto = aesEncryption.CreateDecryptor();
    byte[] encryptedBytes = Convert.FromBase64CharArray(iEncryptedText.ToCharArray(), 0, iEncryptedText.Length);
    return ASCIIEncoding.UTF8.GetString(decrypto.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length));
}
#endregion

hi fairly new to the cryptography...
when im implementing the above code im getting a error while decrypting..
"Padding is invalid and cannot be removed."

please suggest a resolution
thanks and regards

How-to save -safely- the private key ? Windows registry ? in disk ?

I use ASP.NET applications.

Test your code

static void Main(string[] args)
{           
    string plainStr = "The quick red fox jumps over the lazy brown dog.";           
    Console.WriteLine("Original Text: {0}", plainStr);           
    int keySize = 256;           
    string completeEncodedKey = GenerateKey(keySize);                       
    Console.WriteLine("Using complete key '{0}'", completeEncodedKey);           
    string encryptedText = Encrypt(plainStr, completeEncodedKey, keySize);           
    Console.WriteLine("Encrypted Text: {0}", encryptedText);           
    string decrypted = Decrypt(encryptedText, completeEncodedKey, keySize);           
    Console.WriteLine("Decrypted Text: {0}", decrypted);           
    Console.Read();       
}