TlsEccUtilities
using Org.BouncyCastle.Tls.Crypto;
using Org.BouncyCastle.Utilities;
using System.IO;
namespace Org.BouncyCastle.Tls
{
public abstract class TlsEccUtilities
{
public static TlsECConfig CreateNamedECConfig(TlsContext context, int namedGroup)
{
if (NamedGroup.GetCurveBits(namedGroup) < 1)
throw new TlsFatalAlert(80);
return new TlsECConfig(namedGroup);
}
public static int GetMinimumCurveBits(int cipherSuite)
{
return IsEccCipherSuite(cipherSuite) ? 1 : 0;
}
public static bool IsEccCipherSuite(int cipherSuite)
{
switch (TlsUtilities.GetKeyExchangeAlgorithm(cipherSuite)) {
case 16:
case 17:
case 18:
case 19:
case 20:
case 24:
case 26:
return true;
default:
return false;
}
}
public static void CheckPointEncoding(int namedGroup, byte[] encoding)
{
if (TlsUtilities.IsNullOrEmpty(encoding))
throw new TlsFatalAlert(47);
if ((uint)(namedGroup - 29) > 1) {
switch (encoding[0]) {
case 4:
break;
default:
throw new TlsFatalAlert(47);
}
}
}
public static TlsECConfig ReceiveECDHConfig(TlsContext context, Stream input)
{
if (TlsUtilities.ReadUint8(input) != 3)
throw new TlsFatalAlert(40);
int num = TlsUtilities.ReadUint16(input);
if (NamedGroup.RefersToAnECDHCurve(num)) {
int[] clientSupportedGroups = context.SecurityParameters.ClientSupportedGroups;
if (clientSupportedGroups == null || Arrays.Contains(clientSupportedGroups, num))
return new TlsECConfig(num);
}
throw new TlsFatalAlert(47);
}
public static void WriteECConfig(TlsECConfig ecConfig, Stream output)
{
WriteNamedECParameters(ecConfig.NamedGroup, output);
}
public static void WriteNamedECParameters(int namedGroup, Stream output)
{
if (!NamedGroup.RefersToASpecificCurve(namedGroup))
throw new TlsFatalAlert(80);
TlsUtilities.WriteUint8((short)3, output);
TlsUtilities.CheckUint16(namedGroup);
TlsUtilities.WriteUint16(namedGroup, output);
}
}
}