using System; using System.Text; using System.Security.Cryptography; public class Test { public static void Main() { var pkey = "lPtWy3z5nGO6qxf3U2wLbiZb+EfxVXNVhB/RylNI0I1/5/3W/b8/8dIt7Xv2yizRHMFIQbvj1j5zrf6lVERvQVE+kbAkRVJ9AsholCqMuOaPSv5iQB5m6zba1AenJK2Cxe+WOdJ1DbAVR1A8PMkMppojgU9YHPyjObNcU8+OCzM=AQAB"; var cipher = new RSACryptoServiceProvider(); cipher.FromXmlString(pkey); byte[] data = Encoding.UTF8.GetBytes("some message"); byte[] cipherText = cipher.Encrypt(data, false); var encrypted = Convert.ToBase64String(cipherText); Console.WriteLine(encrypted); } }