init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Tls/TlsSRTPUtils.cs

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+using System;
+using System.Collections;
+using System.IO;
+
+namespace Org.BouncyCastle.Crypto.Tls;
+
+public abstract class TlsSRTPUtils
+{
+	public static void AddUseSrtpExtension(IDictionary extensions, UseSrtpData useSRTPData)
+	{
+		extensions[14] = CreateUseSrtpExtension(useSRTPData);
+	}
+
+	public static UseSrtpData GetUseSrtpExtension(IDictionary extensions)
+	{
+		byte[] extensionData = TlsUtilities.GetExtensionData(extensions, 14);
+		if (extensionData != null)
+		{
+			return ReadUseSrtpExtension(extensionData);
+		}
+		return null;
+	}
+
+	public static byte[] CreateUseSrtpExtension(UseSrtpData useSrtpData)
+	{
+		if (useSrtpData == null)
+		{
+			throw new ArgumentNullException("useSrtpData");
+		}
+		MemoryStream memoryStream = new MemoryStream();
+		TlsUtilities.WriteUint16ArrayWithUint16Length(useSrtpData.ProtectionProfiles, memoryStream);
+		TlsUtilities.WriteOpaque8(useSrtpData.Mki, memoryStream);
+		return memoryStream.ToArray();
+	}
+
+	public static UseSrtpData ReadUseSrtpExtension(byte[] extensionData)
+	{
+		if (extensionData == null)
+		{
+			throw new ArgumentNullException("extensionData");
+		}
+		MemoryStream memoryStream = new MemoryStream(extensionData, writable: true);
+		int num = TlsUtilities.ReadUint16(memoryStream);
+		if (num < 2 || (num & 1) != 0)
+		{
+			throw new TlsFatalAlert(50);
+		}
+		int[] protectionProfiles = TlsUtilities.ReadUint16Array(num / 2, memoryStream);
+		byte[] mki = TlsUtilities.ReadOpaque8(memoryStream);
+		TlsProtocol.AssertEmpty(memoryStream);
+		return new UseSrtpData(protectionProfiles, mki);
+	}
+}