轉換

 1 public static string XmlPublicKeyToPem(string xmlPublicKey)
 2         {
 3             RSAParameters rsaParam;
 4             using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
 5             {
 6                 rsa.FromXmlString(xmlPublicKey);
 7                 rsaParam = rsa.ExportParameters(false
 
);
 8             }
 9             RsaKeyParameters param = new RsaKeyParameters(false, new BigInteger(1, rsaParam.Modulus), new BigInteger(1, rsaParam.Exponent));
10 
11             string pemPublicKeyStr = null;
12             using (var ms = new MemoryStream())
13             {
14                 using
 
 (var sw = new StreamWriter(ms))
15                 {
16                     var pemWriter = new Org.BouncyCastle.OpenSsl.PemWriter(sw);
17                     pemWriter.WriteObject(param);
18                     sw.Flush();
19 
20                     byte[] buffer = new byte[ms.Length];
21                     ms.Position = 0
 
;
22                     ms.Read(buffer, 0, (int)ms.Length);
23                     pemPublicKeyStr = Encoding.UTF8.GetString(buffer);
24                 }
25             }
26             return pemPublicKeyStr;
27         }

需要下載BouncyCastle 

可以去官網中直接下載dll檔案在需要的專案中引用dll

地址：https://bouncycastle.org/

c#版選擇如下

 或者在管理nuget包中下載