def test_decryption():
g = _default_crypto['generator']
p = _default_crypto['modulus']
q = _default_crypto['order']
texts = [0, 1, 2, 3, 4]
keys = [13, 14, 15, 16]
publics = [pow(g, x, p) for x in keys]
pk = 1
for y in publics:
pk = (pk * y) % p
cts = []
rands = []
for t in texts:
ct = encrypt(t, p, g, q, pk)
cts.append((ct[0], ct[1]))
rands.append(ct[2])
all_factors = []
for x in keys:
factors = compute_decryption_factors(p, g, q, x, cts)
all_factors.append(factors)
master_factors = combine_decryption_factors(p, all_factors)
pts = []
for (alpha, beta), factor in zip(cts, master_factors):
pts.append(decrypt_with_decryptor(p, g, q, beta, factor))
assert pts == texts
cfm = {
'modulus': p,
'generator': g,
'order': q,
'public': pk,
'original_ciphers': cts,
'mixed_ciphers': cts
}
mix1 = mix_ciphers(cfm)
mix = mix_ciphers(mix1)
cts = mix['mixed_ciphers']
all_factors = []
for x in keys:
factors = compute_decryption_factors(p, g, q, x, cts)
all_factors.append(factors)
master_factors = combine_decryption_factors(p, all_factors)
pts = []
for (alpha, beta), factor in zip(cts, master_factors):
pts.append(decrypt_with_decryptor(p, g, q, beta, factor))
assert sorted(pts) == sorted(texts)
def generate_vote(p, g, q, y, choices, nr_candidates=None):
if isinstance(choices, int):
nr_candidates = choices
selection = get_random_selection(nr_candidates, full=0)
else:
nr_candidates = nr_candidates or (max(choices) if choices else 0) + 1
selection = to_relative_answers(choices, nr_candidates)
encoded = gamma_encode(selection, nr_candidates)
ct = encrypt(encoded, p, g, q, y)
alpha, beta, rand = ct
proof = prove_encryption(p, g, q, alpha, beta, rand)
commitment, challenge, response = proof
answer = {}
answer['encryption_proof'] = (commitment, challenge, response)
answer['choices'] = [{'alpha': alpha, 'beta': beta}]
encrypted_vote = {}
encrypted_vote['answers'] = [answer]
encrypted_vote['election_uuid'] = ''
encrypted_vote['election_hash'] = ''
return encrypted_vote, encoded, rand
def generate_vote(p, g, q, y, choices):
if isinstance(choices, int):
nr_candidates = choices
selection = get_random_selection(nr_candidates, full=0)
else:
nr_candidates = (max(choices) if choices else 0) + 1
selection = to_relative_answers(choices, nr_candidates)
encoded = gamma_encode(selection, nr_candidates)
ct = encrypt(encoded, p, g, q, y)
alpha, beta, rand = ct
proof = prove_encryption(p, g, q, alpha, beta, rand)
commitment, challenge, response = proof
answer = {}
answer['encryption_proof'] = (commitment, challenge, response)
answer['choices'] = [{'alpha': alpha, 'beta': beta}]
encrypted_vote = {}
encrypted_vote['answers'] = [answer]
encrypted_vote['election_uuid'] = ''
encrypted_vote['election_hash'] = ''
return encrypted_vote, encoded, rand
def main_verify(sigfile, randomness=None, plaintext=None):
with open(sigfile) as f:
signature = f.read()
vote_info = verify_vote_signature(signature)
signed_vote, crypto, trustees, candidates, comments = vote_info
eb = signed_vote['encrypted_ballot']
public = eb['public']
modulus, generator, order = crypto
beta = eb['beta']
print 'VERIFIED: Authentic Signature'
if randomness is None:
return
nr_candidates = len(candidates)
encoded = decrypt_with_randomness(modulus, generator, order,
public, beta, randomness)
if plaintext is not None:
if plaintext != encoded:
print 'FAILED: Plaintext Mismatch'
ct = encrypt(plaintext, modulus, generator, order, randomness)
_alpha, _beta, _randomness = ct
alpha = eb['alpha']
if (alpha, beta) != (_alpha, _beta):
print 'FAILED: Invalid Encryption'
max_encoded = gamma_encoding_max(nr_candidates) + 1
print "plaintext: %d" % encoded
print "max plaintext: %d" % max_encoded
if encoded > max_encoded:
print "FAILED: Invalid Vote. Cannot decode."
return
selection = gamma_decode(encoded, nr_candidates)
choices = to_absolute_answers(selection, nr_candidates)
print ""
for i, o in enumerate(choices):
print "%d: [%d] %s" % (i, o, candidates[o])
print ""
def main_verify(sigfile, randomness=None, plaintext=None):
with open(sigfile) as f:
signature = f.read()
vote_info = verify_vote_signature(signature)
signed_vote, crypto, trustees, candidates, comments = vote_info
eb = signed_vote['encrypted_ballot']
public = eb['public']
modulus, generator, order = crypto
beta = eb['beta']
print 'VERIFIED: Authentic Signature'
if randomness is None:
return
nr_candidates = len(candidates)
encoded = decrypt_with_randomness(modulus, generator, order,
public, beta, randomness)
if plaintext is not None:
if plaintext != encoded:
print 'FAILED: Plaintext Mismatch'
ct = encrypt(plaintext, modulus, generator, order, randomness)
_alpha, _beta, _randomness = ct
alpha = eb['alpha']
if (alpha, beta) != (_alpha, _beta):
print 'FAILED: Invalid Encryption'
max_encoded = gamma_encoding_max(nr_candidates) + 1
print "plaintext: %d" % encoded
print "max plaintext: %d" % max_encoded
if encoded > max_encoded:
print "FAILED: Invalid Vote. Cannot decode."
return
selection = gamma_decode(encoded, nr_candidates)
choices = to_absolute_answers(selection, nr_candidates)
print ""
for i, o in enumerate(choices):
print "%d: [%d] %s" % (i, o, candidates[o])
print ""