System.Security.Cryptography.CryptographicException: 系统找不到指定的文件。

将

 System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); 

改为

 CspParameters RSAParams = new CspParameters();

            RSAParams.Flags = CspProviderFlags.UseMachineKeyStore;

            System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(1024, RSAParams);