使用C＃从event.message.text返回的字符串进行3des解密

Question

How do I properly convert the input text so that it decrypts properly I get an error saying

Error CS1503 Argument 1: cannot convert from 'string' to 'char[]'

whats the proper way to parse the first parameter of TransfromFinalBlock of the decryption interface? thanks

private static void Bot_OnMessage4(object sender, MessageEventArgs e)
    {
        ICryptoTransform decrypt = des.CreateDecryptor();
        String[] dd = new String[1];
        dd[1]= utf8.GetString(decrypt.TransformFinalBlock(utf8.GetBytes(**e.Message.Text**, 0, utf8.GetBytes(e.Message.Text).Length)));
        Bot.SendTextMessageAsync(e.Message.Chat.Id, "message to decrypt is  \n" + e.Message.Text );
        Bot.SendTextMessageAsync(e.Message.Chat.Id, "decrypted message is  \n" + dd[1]);

Answer 1

You seem to be already trying to fix your issues, correctly blaming your input:

utf8.GetBytes(e.Message.Text, 0, utf8.GetBytes(e.Message.Text).Length)

The problem is that modern crypto acts on bytes, and returns a ciphertext where each byte can have any value . This means that the ciphertext may also contain bytes that do not represent any character . In other words, the ciphertext is not really text .

So there are two things you can do about it:

1. keep handling the ciphertext as bytes or byte streams;
2. encode the ciphertext to a binary encoding such as base 64 and decode before you decrypt.

Keeping the ciphertext in binary should be preferred, but it is not always possible if the interface with the rest of the system (the Message in this case) requires a textual string.

---

Your error doesn't have anything to do about this, but if you follow above advice you don't need utf8.GetBytes anymore.

You should use the single argument GetBytes method to get rid of the compile error, but your code would still fail during runtime (although it could succeed because the right bytes are generated by chance).