# HG changeset patch
# User Janus Dam Nielsen <[email protected]>
# Date 1254816324 -7200
# Node ID 94086392cb3c34db1672660c9711cbd4941c991f
# Parent bb9566f09d3faebe29cb9a689051dad7da3a61e5
Implementation of addition command.
diff --git a/viff/orlandi.py b/viff/orlandi.py
--- a/viff/orlandi.py
+++ b/viff/orlandi.py
@@ -20,6 +20,7 @@
from viff.runtime import Runtime, Share, ShareList, gather_shares
from viff.util import rand
from viff.constants import TEXT
+from viff.field import FieldElement
from hash_broadcast import HashBroadcastMixin
@@ -315,6 +316,69 @@
self.activate_reactor()
return s
+
+ def add(self, share_a, share_b):
+ """Addition of shares.
+
+ Communication cost: none.
+
+ Each party ``P_i`` computes:
+ ``[z]_i = [x]_i + [y]_i
+ = (x_i + y_i mod p, rho_xi + rho_yi mod p, C_x * C_y)``.
+
+ """
+ def is_share(s, field):
+ if not isinstance(s, Share):
+ if not isinstance(s, FieldElement):
+ s = field(s)
+ (v, rhov, Cv) = self._additive_constant(field(0), s)
+ return OrlandiShare(self, field, v, rhov, Cv)
+ return s
+
+ # Either share_a or share_b must have an attribute called "field".
+ field = getattr(share_a, "field", getattr(share_b, "field", None))
+
+ share_a = is_share(share_a, field)
+ share_b = is_share(share_b, field)
+
+ # Add rho_xi and rho_yi and compute the commitment.
+ def compute_sums((x, y)):
+ (zi, (rhozi1, rhozi2), Cz) = self._plus(x, y)
+ return OrlandiShare(self, field, zi, (rhozi1, rhozi2), Cz)
+
+ result = gather_shares([share_a, share_b])
+ result.addCallbacks(compute_sums, self.error_handler)
+ return result
+
+ def _additive_constant(self, zero, field_element):
+ """Greate an additive constant.
+
+ Any additive constant can be interpreted as:
+ ``[c]_1 = (c, 0, Com_ck(c,0))`` and
+ ``[c]_i = (0, 0, Com_ck(c,0)) for i != 1``.
+ """
+ v = zero
+ if self.id == 1:
+ v = field_element
+ Cx = commitment.commit(field_element.value, zero.value, zero.value)
+ return (v, (zero, zero), Cx)
+
+ def _plus(self, x, y):
+ """Addition of share-tuples *x* and *y*.
+
+ Each party ``P_i`` computes:
+ ``[x]_i = (x_i, rho_xi, C_x)``
+ ``[y]_i = (y_i, rho_yi, C_y)``
+ ``[z]_i = [x]_i + [y]_i
+ = (x_i + y_i mod p, rho_xi + rho_yi mod p, C_x * C_y)``.
+ """
+ (xi, (rhoxi1, rhoxi2), Cx) = x
+ (yi, (rhoyi1, rhoyi2), Cy) = y
+ zi = xi + yi
+ rhozi1 = rhoxi1 + rhoyi1
+ rhozi2 = rhoxi2 + rhoyi2
+ Cz = Cx * Cy
+ return (zi, (rhozi1, rhozi2), Cz)
def error_handler(self, ex):
print "Error: ", ex
diff --git a/viff/test/test_orlandi_runtime.py
b/viff/test/test_orlandi_runtime.py
--- a/viff/test/test_orlandi_runtime.py
+++ b/viff/test/test_orlandi_runtime.py
@@ -75,7 +75,7 @@
def test_random_share(self, runtime):
"""Test creation of a random shared number."""
- self.Zp =
GF(6277101735386680763835789423176059013767194773182842284081)
+ self.Zp =
GF(6277101735386680763835789423176059013767194773182842284081)
def check(v):
self.assertEquals(True, True)
@@ -86,3 +86,78 @@
return d
+ @protocol
+ def test_sum(self, runtime):
+ """Test addition of two numbers."""
+
+ self.Zp =
GF(6277101735386680763835789423176059013767194773182842284081)
+
+ x1 = 42
+ y1 = 7
+
+ def check(v):
+ self.assertEquals(v, x1 + y1)
+
+ if 1 == runtime.id:
+ x2 = runtime.secret_share([1], self.Zp, x1)
+ else:
+ x2 = runtime.secret_share([1], self.Zp)
+
+ if 3 == runtime.id:
+ y2 = runtime.secret_share([3], self.Zp, y1)
+ else:
+ y2 = runtime.secret_share([3], self.Zp)
+
+ z2 = runtime.add(x2, y2)
+ d = runtime.open(z2)
+ d.addCallback(check)
+ return d
+
+ @protocol
+ def test_sum_plus(self, runtime):
+ """Test addition of two numbers."""
+
+ self.Zp =
GF(6277101735386680763835789423176059013767194773182842284081)
+
+ x1 = 42
+ y1 = 7
+
+ def check(v):
+ self.assertEquals(v, x1 + y1)
+
+ if 1 == runtime.id:
+ x2 = runtime.secret_share([1], self.Zp, x1)
+ else:
+ x2 = runtime.secret_share([1], self.Zp)
+
+ if 3 == runtime.id:
+ y2 = runtime.secret_share([3], self.Zp, y1)
+ else:
+ y2 = runtime.secret_share([3], self.Zp)
+
+ z2 = x2 + y2
+ d = runtime.open(z2)
+ d.addCallback(check)
+ return d
+
+ @protocol
+ def test_sum_constant(self, runtime):
+ """Test addition of two numbers."""
+
+ self.Zp =
GF(6277101735386680763835789423176059013767194773182842284081)
+
+ x1 = 42
+ y1 = 7
+
+ def check(v):
+ self.assertEquals(v, x1 + y1)
+
+ if 1 == runtime.id:
+ x2 = runtime.secret_share([1], self.Zp, x1)
+ else:
+ x2 = runtime.secret_share([1], self.Zp)
+
+ z2 = x2 + y1
+ d = runtime.open(z2)
+ d.addCallback(check)
+ return d
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