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- def open_2pc(party0_share, party1_share):
- return party0_share + party1_share
- def verify_2pc_mac_check(party0_mac, party1_mac):
- assert party0_mac+party1_mac == 0
- global_key = random.randint(0, p)
- class ECAuthenticatedShare(object):
- """
- additive share
- """
- def __init__(self, share, mac=None, modifier=None):
- self.share = share
- self.mac = global_key * self.share if mac==None else mac
- self.public_modifier = 0 if modifier == None else modifier # carry out extra addition/subtraction by public scalars until opening
- def __repr__(self):
- return "share: %s, mac: %s"%(self.share, self.mac)
- # SPDZ mac authentication
- def authenticated_open(self, peer_authenticated_share):
- opened_share = open_2pc(self.share, peer_authenticated_share.share)
- mac_key = random.randint(0,global_key)
- mac_share = mac_key * (opened_share + self.public_modifier) - self.mac
- peer_mac_key = global_key - mac_key
- peer_mac_share = peer_mac_key * (opened_share + peer_authenticated_share.public_modifier) - peer_authenticated_share.mac
- assert (mac_share + peer_mac_share) == 0
- return opened_share
- def mul_scalar(self, scalar):
- return ECAuthenticatedShare(self.share * scalar, self.mac * scalar, self.public_modifier * scalar)
- def add_point(self, point, party_id):
- return ECAuthenticatedShare(self.share + point, self.mac , self.public_modifier - point) if party_id ==0 else ECAuthenticatedShare(self.share, self.mac, self.public_modifier - point)
-
- def __add__(self, rhs):
- '''
- add additive shares
- '''
- return ECAuthenticatedShare(self.share + rhs.share, self.mac + rhs.mac, self.public_modifier + rhs.public_modifier)
- def __sub__(self, rhs):
- '''
- sub additive shares
- '''
- return ECAuthenticatedShare(self.share - rhs.share, self.mac - rhs.mac, self.public_modifier - rhs.public_modifier)
- class ScalingECAuthenticatedShares(object):
- def __init__(self, alpha, beta, triplet, party_id):
- # authenticated shares
- self.alpha_as = alpha
- self.beta_as = beta
- self.a_as = triplet[0]
- self.b_as = triplet[1]
- self.c_as = triplet[2]
- self.party_id = party_id
- def __mul__(self, peer_share):
- generator = CurvePoint.generator()
-
- masked_e_share = self.beta_as - self.b_as
- peer_masked_e_share = peer_share.beta_as - peer_share.b_as
- e = open_2pc(masked_e_share.share, peer_masked_e_share.share)
- peer_masked_d_share = peer_share.alpha_as - peer_share.a_as.mul_point(generator)
- masked_d_share = self.alpha_as - self.a_as.mul_point(generator)
- d = open_2pc(masked_d_share.share, peer_masked_d_share.share)
- return (self.b_as.mul_point(d) + self.a_as.mul_point(generator).mul_scalar(e) + self.c_as.mul_point(generator)).add_point(d * e, self.party_id)
- class MSM(object):
- def __init__(self, points, scalars, source, party_id):
- '''
- naive multi scalar multiplicatin, between authenticatedpointsshares, and authenticatedscalarshares
- '''
- self.points = points
- self.scalars = scalars
- self.source = source
- self.party_id = party_id
- def msm(self):
- assert (len(self.points) == len(self.scalars))
- beaver = self.source
- point_scalars = []
- for point, scalar in zip(self.points, self.scalars):
- point_scalars += [ScalingECAuthenticatedShares(point, scalar, beaver.triplet(self.party_id), self.party_id)]
- return point_scalars
- def sum(self):
- return sum(self.msm())
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