public bool KeyGenerationProtocol_UpdateKey(
IInputChannel input_channel)
{
BigInteger foo = input_channel.Recieve();
BigInteger c = input_channel.Recieve();
BigInteger r = input_channel.Recieve();
// verify the in-group property
if (!CheckElement(foo))
{
System.Diagnostics.Debug.WriteLine("CheckElement incorrect");
return(false);
}
// check the size of $r$
if (ToolsMathBigInteger.CompareAbs(r, q) >= 0)
{
System.Diagnostics.Debug.WriteLine("compare_absolutes incorrect");
return(false);
}
// verify the proof of knowledge [CaS97]
BigInteger t = g.ModPow(r, p);
r = foo.ModPow(c, p);
t = t * r;
t = t % p;
r = mpz_shash_tools.mpz_shash(new BigInteger [] { g, foo, t });
// c = mpz_shash_tools.mpz_shash(new BigInteger [] {g, h_i, t});
if (c != r)
{
System.Diagnostics.Debug.WriteLine("c != r " + c.BitLength() + " " + r.BitLength());
System.Diagnostics.Debug.WriteLine("g " + g.BitLength() + " foo " + foo.BitLength() + " t " + t.BitLength());
return(false);
}
// update the global key h
h *= foo;
h = h % p;
// store the public key
BigInteger tmp = foo;
t = mpz_shash_tools.mpz_shash(foo);
h_j.Add(t.ToString(), tmp);
// finish
return(true);
}
bool OR_Verify(
BigInteger y_1,
BigInteger y_2,
BigInteger g_1,
BigInteger g_2,
IInputChannel input_channel)
{
BigInteger c_1 = input_channel.Recieve();
BigInteger c_2 = input_channel.Recieve();
BigInteger r_1 = input_channel.Recieve();
BigInteger r_2 = input_channel.Recieve();
BigInteger c;
// check the size of $r_1$ and $r_2$
if ((ToolsMathBigInteger.CompareAbs(r_1, q) >= 0L) || (ToolsMathBigInteger.CompareAbs(r_2, q) >= 0L))
{
return(false);
}
// verify (S)PK ($y_1 = g_1^\alpha \vee y_2 = g_2^\beta$) [CaS97]
BigInteger t_1 = y_1.ModPow(c_1, p);
BigInteger tmp = g_1.ModPow(r_1, p);
t_1 = t_1 * tmp;
t_1 = t_1 % p;
BigInteger t_2 = y_2.ModPow(c_2, p);
tmp = g_2.ModPow(r_2, p);
t_2 = t_2 * tmp;
t_2 = t_2 % p;
// check the equation
// $c_1 + c_2 \stackrel{?}{=} \mathcal{H}(g_1, y_1, g_2, y_2, t_1, t_2)$
tmp = c_1 + c_2;
// c = c % q; ERROR this does nothing
c = mpz_shash_tools.mpz_shash(new BigInteger [] { g_1, y_1, g_2, y_2, t_1, t_2 });
c = c % q;
if (tmp != c)
{
return(false);
}
// finish
return(true);
}
bool CP_Verify(
BigInteger x,
BigInteger y,
BigInteger gg,
BigInteger hh,
IInputChannel input_channel,
bool fpowm_usage)
{
BigInteger a;
BigInteger b;
BigInteger c = input_channel.Recieve();
BigInteger r = input_channel.Recieve();
// check the size of $r$
if (ToolsMathBigInteger.CompareAbs(r, q) >= 0)
{
return(false);
}
// verify proof of knowledge (equality of discrete logarithms) [CaS97]
a = gg.ModPow(r, p);
b = x.ModPow(c, p);
a = a * b;
a = a % p;
b = hh.ModPow(r, p);
r = y.ModPow(c, p);
b = b * r;
b = b % p;
r = mpz_shash_tools.mpz_shash(new BigInteger [] { a, b, x, y, gg, hh });
if (r != c)
{
return(false);
}
// finish
return(true);
}