ASP.Net CryptographicException: The input data is not a complete block

Hi mukesh1,

mukesh1 says:

B rO6nwUQFVv5AuspaA3wSplBAQAVlACNLU1dp/c4fO28sstJyPOQMHPkaPMB8q8 0lGRnK otUGOm4uU68Hxw==

The encrypted text you have provided is not a valid string for decryption. Space character not allow.

Refer the below example with valid encrypted and decrypted value.

C#

protected void Page_Load(object sender, EventArgs e)
{
    var code = (24 + "AZp4NY3Wq" + 24 + "lp78tsI5g" + 1 + 24).ToString();
    string encrypt = Encrypt(code);
    string decrypt = Decrypt(encrypt);
    Response.Write("Encrypted text : <b>" + encrypt + "</b></br>Decrypted text : <b>" + decrypt + "</b>");
}

private string Decrypt(string cipherText)
{
    string EncryptionKey = "MAKV2SPBNI99212";
    byte[] cipherBytes = Convert.FromBase64String(cipherText);
    using (Aes encryptor = Aes.Create())
    {
        Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
        encryptor.Key = pdb.GetBytes(32);
        encryptor.IV = pdb.GetBytes(16);
        encryptor.Mode = CipherMode.CBC;
        using (MemoryStream ms = new MemoryStream())
        {
            using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
            {
                cs.Write(cipherBytes, 0, cipherBytes.Length);
                cs.Close();
            }
            cipherText = Encoding.Unicode.GetString(ms.ToArray());
        }
    }
    return cipherText;
}

private string Encrypt(string clearText)
{
    string EncryptionKey = "MAKV2SPBNI99212";
    byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
    using (Aes encryptor = Aes.Create())
    {
        Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(EncryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
        encryptor.Key = pdb.GetBytes(32);
        encryptor.IV = pdb.GetBytes(16);
        using (MemoryStream ms = new MemoryStream())
        {
            using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cs.Write(clearBytes, 0, clearBytes.Length);
                cs.Close();
            }
            clearText = Convert.ToBase64String(ms.ToArray());
        }
    }
    return clearText;
}

Output

Encrypted text : B+rO6nwUQFVv5AuspaA3wSplBAQAVlACNLU1dp/c4fO28sstJyPOQMHPkaPMB8q8+0lGRnK+otUGOm4uU68Hxw== Decrypted text : 24AZp4NY3Wq24lp78tsI5g124

When it is read it is decoded so the + becomes a space.

So use replace function to replace the space character with + character before passing for decryption.