Added a testcase, and added a shares check in combine_shares

honeybadgerbft/crypto/threshenc/tpke.py

@@ -123,11 +123,17 @@ def combine_shares(self, (U,V,W), shares):
         """ """
         # sigs: a mapping from idx -> sig
         S = set(shares.keys())
+        print S
         assert S.issubset(range(self.l))
 
         # ASSUMPTION
         # assert self.verify_ciphertext((U,V,W))
 
+        # ASSUMPTION
+        for j,share in shares.iteritems():
+            if j == 0: print share
+            self.verify_share( j, share, (U,V,W) )
+
         mul = lambda a,b: a*b
         res = reduce(mul,
                      [share ** self.lagrange(S, j)

test/test_threshenc.py

@@ -0,0 +1,52 @@
+import unittest
+from charm.toolbox.pairinggroup import PairingGroup,ZR,G1,G2,GT,pair
+import random
+from honeybadgerbft.crypto.threshenc.tpke import TPKEPublicKey, TPKEPrivateKey, dealer
+from Crypto.Hash import SHA256
+from Crypto import Random
+from Crypto.Cipher import AES
+
+def test_threshenc():
+    PK, SKs = dealer(players=100,k=35)
+
+    m = SHA256.new('hello world').digest()
+    C = PK.encrypt(m)
+
+    assert PK.verify_ciphertext(C)
+
+    shares = [sk.decrypt_share(C) for sk in SKs]
+    for i,share in enumerate(shares):
+        assert PK.verify_share(i, share, C)
+
+    SS = range(PK.l)
+    for i in range(1):
+        random.shuffle(SS)
+        S = set(SS[:PK.k])
+
+        m_ = PK.combine_shares(C, dict((s,shares[s]) for s in S))
+        assert m_ == m
+
+def test_threshenc2():
+    # Failure cases
+    PK, SKs = dealer(players=100,k=35)
+
+    m = SHA256.new('hello world').digest()
+    C = PK.encrypt(m)
+
+    assert PK.verify_ciphertext(C)
+
+    shares = [sk.decrypt_share(C) for sk in SKs]
+    for i,share in enumerate(shares):
+        assert PK.verify_share(i, share, C)
+
+    SS = range(PK.l)
+    random.shuffle(SS)
+    # Perturb one of the keys
+    shares[SS[0]] += shares[SS[0]]
+    S = set(SS[:PK.k])
+
+    try:
+        m_ = PK.combine_shares(C, dict((s,shares[s]) for s in S))
+        assert m_ == m
+    except AssertionError: pass
+    else: assert False, "Combine shares should have raised an error"