CODEWITHSUNDEEP
c#encryption
Fraz Sundal
Fraz Sundal

Reputation: 10448

length of the data to decrypt is invalid in c#

While decrypting a string I am getting length of the data to decrypt is invalid error when i call FlushFinalBlock function

key = Encoding.UTF8.GetBytes(stringKey.Substring(0, 8));
DESCryptoServiceProvider des = new DESCryptoServiceProvider();
Byte[] byteArray = Convert.FromBase64String(text);
MemoryStream memoryStream = new MemoryStream();
CryptoStream cryptoStream = new CryptoStream(memoryStream, des.CreateDecryptor(key, IV), CryptoStreamMode.Write);
cryptoStream.Write(byteArray, 0, byteArray.Length);
cryptoStream.FlushFinalBlock();
return Encoding.UTF8.GetString(memoryStream.ToArray());

what is the issue and how to resolve it?

Upvotes: 1

Views: 10919

Answers (1)

Darin Dimitrov
Darin Dimitrov

Reputation: 1038780

You didn't show how is the string encrypted, whether you are using the same keys and IV, etc... Here's a full working example you could adapt to your scenario:

class Program
{
    private static byte[] DESKey = { 200, 5, 78, 232, 9, 6, 0, 4 };
    private static byte[] DESInitializationVector = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

    static void Main()
    {
         var encrypted = Encrypt("foo bar");
         Console.WriteLine(encrypted);
         var decrypted = Decrypt(encrypted);
         Console.WriteLine(decrypted);
    }

    public static string Encrypt(string value)
    {
        using (var cryptoProvider = new DESCryptoServiceProvider())
        using (var memoryStream = new MemoryStream())
        using (var cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateEncryptor(DESKey, DESInitializationVector), CryptoStreamMode.Write))
        using (var writer = new StreamWriter(cryptoStream))
        {
            writer.Write(value);
            writer.Flush();
            cryptoStream.FlushFinalBlock();
            writer.Flush();
            return Convert.ToBase64String(memoryStream.GetBuffer(), 0, (int)memoryStream.Length);
        }
    }

    public static string Decrypt(string value)
    {
        using(var cryptoProvider = new DESCryptoServiceProvider())
        using(var memoryStream = new MemoryStream(Convert.FromBase64String(value)))
        using(var cryptoStream = new CryptoStream(memoryStream, cryptoProvider.CreateDecryptor(DESKey, DESInitializationVector), CryptoStreamMode.Read))
        using(var reader = new StreamReader(cryptoStream))
        {
            return reader.ReadToEnd();
        }
    }
}

Upvotes: 2

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