// https://tools.ietf.org/html/rfc4357#section-5.2
// https://tools.ietf.org/html/rfc7836#section-4.3
public byte[] Vko(EncryptedPrivateKey encPk, ECPublicKeyParameters y)
{
var x = (ECPrivateKeyParameters)_keyPair.Private;
var ukmBytes = (byte[])encPk.UKM.Clone();
Array.Reverse(ukmBytes);
var ukm = new BigInteger(1, ukmBytes);
var p = ukm.Multiply(x.D).Mod(y.Parameters.Curve.Order);
var kekPoint = y.Q.Multiply(p).Normalize();
var kekPointX = kekPoint.AffineXCoord.ToBigInteger().ToByteArrayUnsigned();
var kekPointY = kekPoint.AffineYCoord.ToBigInteger().ToByteArrayUnsigned();
var kekBytes = new byte[kekPointX.Length + kekPointY.Length];
Array.Copy(kekPointY, 0, kekBytes, 0, kekPointY.Length);
Array.Copy(kekPointX, 0, kekBytes, kekPointY.Length, kekPointX.Length);
Array.Reverse(kekBytes);
var dig = GetDigest();
var kek = new byte[dig.GetDigestSize()];
dig.BlockUpdate(kekBytes, 0, kekBytes.Length);
dig.DoFinal(kek, 0);
return(kek);
}
// https://tools.ietf.org/html/rfc4357#section-5.2
public byte[] Vko(EncryptedPrivateKey encPk, ECPublicKeyParameters sessionKey)
{
var privKey = (ECPrivateKeyParameters)_keyPair.Private;
var ukmBytes = (byte[])encPk.UKM.Clone();
Array.Reverse(ukmBytes);
var ukm = new BigInteger(1, ukmBytes);
var p = ukm.Multiply(privKey.D).Mod(sessionKey.Parameters.Curve.Order);
var kekPoint = sessionKey.Q.Multiply(p).Normalize();
var x = kekPoint.XCoord.ToBigInteger().ToByteArrayUnsigned();
var y = kekPoint.YCoord.ToBigInteger().ToByteArrayUnsigned();
var kekBytes = new byte[64];
Array.Copy(y, 0, kekBytes, 0, 32);
Array.Copy(x, 0, kekBytes, 32, 32);
Array.Reverse(kekBytes);
var kek = new byte[32];
var dig = new Gost3411Digest();
dig.BlockUpdate(kekBytes, 0, kekBytes.Length);
dig.DoFinal(kek, 0);
return(kek);
}
public BigInteger ExportPrivateKey()
{
var context = GetHandle(_cert);
var derive = new KeyDerivation();
derive.Init();
byte[] sessKey, privKeyBlob;
ExportPrivateKey(context, derive.GetPublicKeyBytes(), out sessKey, out privKeyBlob);
_encryptedPkey = new EncryptedPrivateKey(privKeyBlob);
_sk = new SessionKey(sessKey);
var kek = derive.Vko(_encryptedPkey, _sk.GetPublicKey());
var pkey = _encryptedPkey.UnwrapKey(kek);
Array.Reverse(pkey);
return(new BigInteger(1, pkey));
}
public BigInteger ExportPrivateKey()
{
var pkeyInfo = GetPrivateKeyInfo(_cert);
CheckProvider(pkeyInfo);
var provType = (ProviderType)pkeyInfo.ProviderType;
var factory = KeyExportFactory.Create(provType);
var derive = factory.CreateKeyDerivation();
var blob = factory.CreatePrivateKeyBlob();
var privKeyBlob = blob.GetPrivateKeyBlob(_cert.Handle, derive);
_encryptedPkey = factory.CreateEncryptedPrivateKey(privKeyBlob);
_sk = factory.CreateSessionKey(blob.SessionKey);
var kek = derive.Vko(_encryptedPkey, _sk.GetPublicKey());
var pkey = _encryptedPkey.UnwrapKey(kek);
Array.Reverse(pkey);
return(new BigInteger(1, pkey));
}