Windows Application Error: Length of the data to decrypt is invalid

Hi paulrajmca,

Refer below links.

https://forums.asp.net/t/1809148.aspx?Length+of+the+data+to+decrypt+is+invalid+with+rijndael

https://www.codeproject.com/Questions/109523/Length-of-the-data-to-decrypt-is-invalid

Thanks Dharmendr,

But your suggested link code is not working ... kindly give me any other suggestion for this module ... 

Regards,

Paul.S

Hi paulrajmca,

Use below code.

C#

public string Encrypt(string text, string pwd)
{
    byte[] originalBytes = Encoding.UTF8.GetBytes(text);
    byte[] encryptedBytes = null;
    byte[] passwordBytes = Encoding.UTF8.GetBytes(pwd);
    passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
    int saltSize = GetSaltSize(passwordBytes);
    byte[] saltBytes = GetRandomBytes(saltSize);
    byte[] bytesToBeEncrypted = new byte[saltBytes.Length + originalBytes.Length];
    for (int i = 0; i < saltBytes.Length; i++)
    {
        bytesToBeEncrypted[i] = saltBytes[i];
    }
    for (int i = 0; i < originalBytes.Length; i++)
    {
        bytesToBeEncrypted[i + saltBytes.Length] = originalBytes[i];
    }

    encryptedBytes = AES_Encrypt(bytesToBeEncrypted, passwordBytes);

    return Convert.ToBase64String(encryptedBytes);
}
public string Decrypt(string decryptedText, string pwd)
{
    byte[] bytesToBeDecrypted = Convert.FromBase64String(decryptedText);
    byte[] passwordBytes = Encoding.UTF8.GetBytes(pwd);
    passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
    byte[] decryptedBytes = AES_Decrypt(bytesToBeDecrypted, passwordBytes);
    if (decryptedBytes != null)
    {
        int saltSize = GetSaltSize(passwordBytes);
        byte[] originalBytes = new byte[decryptedBytes.Length - saltSize];
        for (int i = saltSize; i < decryptedBytes.Length; i++)
        {
            originalBytes[i - saltSize] = decryptedBytes[i];
        }
        return Encoding.UTF8.GetString(originalBytes);
    }
    else
    {
        return null;
    }
}
public byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
    byte[] encryptedBytes = null;
    byte[] saltBytes = passwordBytes;
    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 (CryptoStream 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)
{
    try
    {
        byte[] decryptedBytes = null;
        byte[] saltBytes = passwordBytes;
        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);
                using (CryptoStream cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
                    cs.Close();
                }
                decryptedBytes = ms.ToArray();
            }
        }
        return decryptedBytes;
    }
    catch (Exception Ex)
    {
        return null;
    }
}
private int GetSaltSize(byte[] passwordBytes)
{
    var key = new Rfc2898DeriveBytes(passwordBytes, passwordBytes, 1000);
    byte[] ba = key.GetBytes(2);
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < ba.Length; i++)
    {
        sb.Append(Convert.ToInt32(ba[i]).ToString());
    }
    int saltSize = 0;
    string s = sb.ToString();
    foreach (char c in s)
    {
        int intc = Convert.ToInt32(c.ToString());
        saltSize = saltSize + intc;
    }

    return saltSize;
}
public byte[] GetRandomBytes(int length)
{
    byte[] ba = new byte[length];
    RNGCryptoServiceProvider.Create().GetBytes(ba);
    return ba;
}