byte[] PerformKeyAgreement(ECPoint other, int keyDataLength)
{
// Diffie-Hellman Primitives
if (_params.D == null)
{
_params.CreateNewPrivateKey();
}
Number sharedSecretField = other.Multiply(_params.D).Export().X;
byte[] sharedSecretValue = new byte[(_params.Domain.Bits >> 3) + ((_params.Domain.Bits & 7) == 0 ? 0 : 1)];
sharedSecretField.CopyToBigEndian(sharedSecretValue, 0, sharedSecretValue.Length);
// KDF
if (_kdf == null)
{
return(sharedSecretValue);
}
_kdf.SharedInfo = _sharedInfo;
return(_kdf.Calculate(sharedSecretValue, keyDataLength));
}
public byte[] PerformKeyAgreement(byte[] otherPublicKey1, byte[] otherPublicKey2, int keyDataLength)
{
ECPoint otherQ1 = new ECPoint(_params.Domain.Group, otherPublicKey1);
ECPoint otherQ2 = new ECPoint(_params.Domain.Group, otherPublicKey2);
IFiniteField ff = _params.Domain.FieldN;
// MQV Primitives
if (_params.KeyPair1.D == null)
{
_params.KeyPair1.CreateNewPrivateKey();
}
if (_params.KeyPair2.D == null)
{
_params.KeyPair2.CreateNewPrivateKey();
}
if (_params.KeyPair2.Q == null)
{
_params.KeyPair2.CreatePublicKeyFromPrivateKey();
}
int logBits = _params.Domain.N.BitCount();
logBits = (logBits >> 1) + ((logBits & 1) == 0 ? 0 : 1);
Number mod = Number.One << logBits;
Number mask = mod - Number.One;
Number q2u = (_params.KeyPair2.Q.Export().X & mask) + mod;
Number s = ff.Add(_params.KeyPair2.D, ff.Multiply(q2u, _params.KeyPair1.D));
Number q2v = (otherQ2.Export().X & mask) + mod;
ECPoint P = otherQ2.Add(otherQ1.Multiply(q2v)).Multiply(s * new Number(new uint[] { _params.Domain.H }));
if (P.IsInifinity())
{
throw new CryptographicException();
}
int keyBytes = (int)((_params.Domain.Bits >> 3) + ((_params.Domain.Bits & 7) == 0 ? 0 : 1));
byte[] sharedSecretValue = P.Export().X.ToByteArray(keyBytes, false);
// KDF
_kdf.SharedInfo = _sharedInfo;
return(_kdf.Calculate(sharedSecretValue, keyDataLength));
}
public byte[] Encrypt(byte[] value, byte[] randomK)
#endif
{
int domainLen = (int)((_domain.Bits >> 3) + ((_domain.Bits & 7) == 0 ? 0 : 1));
int encBlockBytes = (_symmetricAlgo == null ? 0 : _symmetricAlgo.BlockSize >> 3);
int encKeyLen = (_symmetricAlgo == null ? value.Length : _symmetricAlgo.KeySize >> 3);
int encPaddingLen = 0;
int encTotalBytes = value.Length;
int macKeyLen = _mac.HashSize >> 3;
byte[] result;
int ridx = 0;
if (_params.D == null)
{
_params.CreateNewPrivateKey();
}
if (_params.Q == null)
{
_params.CreatePublicKeyFromPrivateKey();
}
if (_symmetricAlgo != null)
{
int mod = value.Length % encBlockBytes;
int rmod = encBlockBytes - mod;
if (mod == 0)
{
if (!(_symmetricAlgo.Padding == PaddingMode.None || _symmetricAlgo.Padding == PaddingMode.Zeros))
{
encPaddingLen = _symmetricAlgo.BlockSize >> 3;
}
}
else
{
encPaddingLen = rmod;
}
encTotalBytes += encPaddingLen;
}
// Step.1
#if !TEST
ECKeyPair pair = new ECKeyPair(null, null, _domain);
#else
ECKeyPair pair = new ECKeyPair(new Number(randomK, false), null, _domain);
#endif
// Step.2
// TODO: 点圧縮を利用しないオプションを追加する
byte[] R = pair.ExportPublicKey(true);
result = new byte[R.Length + encTotalBytes + macKeyLen];
for (int i = 0; i < R.Length; i++)
{
result[ridx++] = R[i];
}
// Step.3 & 4
// TODO: Cofactor Diffie-Hellmanプリミティブを利用するオプションを追加する
byte[] z = _params.Q.Multiply(pair.D).Export().X.ToByteArray(domainLen, false);
// Step.5
byte[] K = _kdf.Calculate(z, encKeyLen + macKeyLen);
// Step.6
byte[] MK = new byte[macKeyLen];
for (int i = 0; i < MK.Length; i++)
{
MK[i] = K[K.Length - MK.Length + i];
}
// Step.7
if (_symmetricAlgo == null)
{
for (int i = 0; i < value.Length; i++)
{
result[ridx++] = (byte)(value[i] ^ K[i]);
}
}
else
{
byte[] EK = new byte[encKeyLen];
for (int i = 0; i < EK.Length; i++)
{
EK[i] = K[i];
}
using (ICryptoTransform transform = _symmetricAlgo.CreateEncryptor(EK, new byte[encBlockBytes])) {
int i = 0;
for (; i < value.Length - encBlockBytes; i += encBlockBytes)
{
transform.TransformBlock(value, i, encBlockBytes, result, ridx + i);
}
byte[] padding = transform.TransformFinalBlock(value, i, value.Length - i);
Buffer.BlockCopy(padding, 0, result, ridx + i, padding.Length);
ridx += i + padding.Length;
}
}
// Step.8
// TODO: HMAC-SHA1-80への対応
_mac.Key = MK;
_mac.Initialize();
_mac.TransformBlock(result, R.Length, encTotalBytes, null, 0);
if (_sharedInfo == null)
{
_mac.TransformFinalBlock(result, 0, 0);
}
else
{
_mac.TransformFinalBlock(_sharedInfo, 0, _sharedInfo.Length);
}
_mac.Hash.CopyTo(result, ridx);
return(result);
}
