/// <summary>
/// Constructs an ECCGroup.
/// <param name="p">The p parameter, representing the prime field domain for the
/// x and y coordinate spaces.</param>
/// <param name="a">The a parameter for the eliptic curve.</param>
/// <param name="b">The b parameter for the eliptic curve.</param>
/// <param name="g_x">The x coordinate of the generator point.</param>
/// <param name="g_y">The y coordinate of the generator point.</param>
/// <param name="n">The order of the group.</param>
/// <param name="groupName">The known name of the group, or null.</param>
/// <param name="curveName">The known name of the curve, or null.</param>
/// </summary>
public ECGroupBCImpl(
byte[] p,
byte[] a,
byte[] b,
byte[] g_x,
byte[] g_y,
byte[] n,
string groupName,
string curveName)
: base(p, a, b, g_x, g_y, n, groupName, curveName)
{
this.curve = new BouncyCastle.FpCurve(
new BCBigInt(1, p),
new BCBigInt(1, a),
new BCBigInt(1, b));
BouncyCastle.ECPoint generator = this.curve.CreatePoint(
new BCBigInt(1, g_x),
new BCBigInt(1, g_y),
false);
this.domainParams = new BouncyCastle.ECDomainParameters(
this.curve,
generator,
new BCBigInt(1, n));
this.g = new ECGroupElementBCImpl(
this.domainParams.G as BouncyCastle.FpPoint);
}
/// <summary>
/// Bouncy castle implementation of multi-exponentiation.
/// </summary>
/// <param name="g">bases</param>
/// <param name="f">exponents</param>
/// <returns></returns>
public override GroupElement MultiExponentiate(GroupElement[] g, FieldZqElement[] f)
{
if (g == null || f == null || g.Length != f.Length)
{
throw new ArgumentException("g and f must be non-null and of the same length");
}
//GroupElement value = Identity;
//for (int i = 0; i < g.Length; i++)
//{
// value *= g[i].Exponentiate(f[i]);
//}
//return value;
BouncyCastle.ECPoint p = curve.Infinity;
int i = 0, limit = g.Length & ~1;
while (i < limit)
{
ECGroupElementBCImpl gi0 = g[i] as ECGroupElementBCImpl;
FieldZqElementBCImpl fi0 = f[i] as FieldZqElementBCImpl;
ECGroupElementBCImpl gi1 = g[i + 1] as ECGroupElementBCImpl;
FieldZqElementBCImpl fi1 = f[i + 1] as FieldZqElementBCImpl;
p = p.Add(BouncyCastle.ECAlgorithms.SumOfTwoMultiplies(gi0.Point, fi0.i, gi1.Point, fi1.i));
i += 2;
}
if (i < g.Length)
{
ECGroupElementBCImpl gi0 = g[i] as ECGroupElementBCImpl;
FieldZqElementBCImpl fi0 = f[i] as FieldZqElementBCImpl;
p = p.Add(gi0.Point.Multiply(fi0.i));
}
return(new ECGroupElementBCImpl(p as BouncyCastle.FpPoint));
}
