1 files changed, 42 insertions, 0 deletions
diff --git a/Crypto/src/crypto/tls/TlsRsaUtilities.cs b/Crypto/src/crypto/tls/TlsRsaUtilities.cs
new file mode 100644
index 000000000..4450ba452
--- /dev/null
+++ b/Crypto/src/crypto/tls/TlsRsaUtilities.cs
@@ -0,0 +1,42 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Crypto.Encodings;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto.Tls
+{
+	public abstract class TlsRsaUtilities
+	{
+		public static byte[] GenerateEncryptedPreMasterSecret(SecureRandom random,
+			RsaKeyParameters rsaServerPublicKey, Stream output)
+		{
+			/*
+			 * Choose a PremasterSecret and send it encrypted to the server
+			 */
+			byte[] premasterSecret = new byte[48];
+			random.NextBytes(premasterSecret);
+			TlsUtilities.WriteVersion(premasterSecret, 0);
+
+			Pkcs1Encoding encoding = new Pkcs1Encoding(new RsaBlindedEngine());
+			encoding.Init(true, new ParametersWithRandom(rsaServerPublicKey, random));
+
+			try
+			{
+				byte[] keData = encoding.ProcessBlock(premasterSecret, 0, premasterSecret.Length);
+                TlsUtilities.WriteOpaque16(keData, output);
+			}
+			catch (InvalidCipherTextException)
+			{
+				/*
+				* This should never happen, only during decryption.
+				*/
+				throw new TlsFatalAlert(AlertDescription.internal_error);
+			}
+
+			return premasterSecret;
+		}
+	}
+}