public PartiallyDecryptedShare Decrypt(EncryptedShare share)
{
return(DecryptBenchmark.Benchmark(() =>
{
var h = Utils.HashToG2(share.U, share.V);
if (!GT.Pairing(G1.Generator, share.W).Equals(GT.Pairing(share.U, h)))
{
throw new Exception("Invalid share!");
}
var ui = share.U * _x;
return new PartiallyDecryptedShare(ui, _id, share.Id);
}));
}
public RawShare FullDecrypt(EncryptedShare share, List <PartiallyDecryptedShare> us)
{
return(FullDecryptBenchmark.Benchmark(() =>
{
if (us.Count < _t)
{
throw new Exception("Insufficient number of shares!");
}
var ids = new HashSet <int>();
foreach (var part in us)
{
if (ids.Contains(part.DecryptorId))
{
throw new Exception($"Id {part.DecryptorId} was provided more than once!");
}
if (part.ShareId != share.Id)
{
throw new Exception($"Share id mismatch for decryptor {part.DecryptorId}");
}
ids.Add(part.DecryptorId);
}
var ys = new List <G1>();
var xs = new List <Fr>();
foreach (var part in us)
{
xs.Add(Fr.FromInt(part.DecryptorId + 1));
ys.Add(part.Ui);
}
var u = MclBls12381.LagrangeInterpolate(xs.ToArray(), ys.ToArray());
return new RawShare(Utils.XorWithHash(u, share.V), share.Id);
}));
}
