c sharp string encryption source code

You can use DSA and RSA, e.g.
using   System;
using   System.Text;
using   System.Security.Cryptography;

class   dsacrypto_SignData   {
public   static   void   Main(String[]   args){
// first convert the string to a byte array, which is all about encoding.
String   str   =   "this   is   a   test.";
byte[]   bytes   =   Encoding.ASCII.GetBytes(str);
// select the signature method, RSA and DSA
DSACryptoServiceProvider   dsac   =   new   DSACryptoServiceProvider();
byte[]   sign   =   dsac.SignData(bytes);
//sign is the signature result.

// below is
certified DSACryptoServiceProvider   dsac2   =   new   DSACryptoServiceProvider();
dsac2.FromXmlString(dsac.ToXmlString(false));
bool   ver   =   dsac2.VerifyData(bytes,   sign);
if   (ver)   {
Console. WriteLine (" by ");
}   else   {
Console.WriteLine(" cannot pass ");
}
}
}

RSA is similar, but RSA is much slower than DSA, but safer than DSA. RSA can choose the size of the keyword, the larger the safer