1 files changed, 70 insertions, 0 deletions
diff --git a/Crypto/src/crypto/tls/TlsDHUtilities.cs b/Crypto/src/crypto/tls/TlsDHUtilities.cs
new file mode 100644
index 000000000..733749ea1
--- /dev/null
+++ b/Crypto/src/crypto/tls/TlsDHUtilities.cs
@@ -0,0 +1,70 @@
+using System;
+using System.IO;
+
+using Org.BouncyCastle.Crypto.Agreement;
+using Org.BouncyCastle.Crypto.Generators;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Tls
+{
+ public abstract class TlsDHUtilities
+ {
+ public static byte[] CalculateDHBasicAgreement(DHPublicKeyParameters publicKey,
+ DHPrivateKeyParameters privateKey)
+ {
+ DHBasicAgreement dhAgree = new DHBasicAgreement();
+ dhAgree.Init(privateKey);
+ BigInteger agreement = dhAgree.CalculateAgreement(publicKey);
+ return BigIntegers.AsUnsignedByteArray(agreement);
+ }
+
+ public static AsymmetricCipherKeyPair GenerateDHKeyPair(SecureRandom random, DHParameters dhParams)
+ {
+ DHBasicKeyPairGenerator dhGen = new DHBasicKeyPairGenerator();
+ dhGen.Init(new DHKeyGenerationParameters(random, dhParams));
+ return dhGen.GenerateKeyPair();
+ }
+
+ public static DHPrivateKeyParameters GenerateEphemeralClientKeyExchange(SecureRandom random,
+ DHParameters dhParams, Stream output)
+ {
+ AsymmetricCipherKeyPair dhAgreeClientKeyPair = GenerateDHKeyPair(random, dhParams);
+ DHPrivateKeyParameters dhAgreeClientPrivateKey =
+ (DHPrivateKeyParameters)dhAgreeClientKeyPair.Private;
+
+ BigInteger Yc = ((DHPublicKeyParameters)dhAgreeClientKeyPair.Public).Y;
+ byte[] keData = BigIntegers.AsUnsignedByteArray(Yc);
+ TlsUtilities.WriteOpaque16(keData, output);
+
+ return dhAgreeClientPrivateKey;
+ }
+
+ public static DHPublicKeyParameters ValidateDHPublicKey(DHPublicKeyParameters key)
+ {
+ BigInteger Y = key.Y;
+ DHParameters parameters = key.Parameters;
+ BigInteger p = parameters.P;
+ BigInteger g = parameters.G;
+
+ if (!p.IsProbablePrime(2))
+ {
+ throw new TlsFatalAlert(AlertDescription.illegal_parameter);
+ }
+ if (g.CompareTo(BigInteger.Two) < 0 || g.CompareTo(p.Subtract(BigInteger.Two)) > 0)
+ {
+ throw new TlsFatalAlert(AlertDescription.illegal_parameter);
+ }
+ if (Y.CompareTo(BigInteger.Two) < 0 || Y.CompareTo(p.Subtract(BigInteger.One)) > 0)
+ {
+ throw new TlsFatalAlert(AlertDescription.illegal_parameter);
+ }
+
+ // TODO See RFC 2631 for more discussion of Diffie-Hellman validation
+
+ return key;
+ }
+ }
+}
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