def grant(private_key, public_key, signer):
kfrags = pre.split_rekey(delegating_privkey=private_key,
signer=signer,
receiving_pubkey=public_key,
threshold=10,
N=20)
return kfrags
def test_correctness_proof_serialization(alices_keys):
delegating_privkey, signing_privkey = alices_keys
delegating_pubkey = delegating_privkey.get_pubkey()
signer = Signer(signing_privkey)
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
params = delegating_privkey.params
_unused_key, capsule = pre._encapsulate(delegating_pubkey)
kfrags = pre.split_rekey(delegating_privkey, signer, pub_key_bob, 1, 2)
# Example of potential metadata to describe the re-encryption request
metadata = b"This is an example of metadata for re-encryption request"
cfrag = pre.reencrypt(kfrags[0], capsule, metadata=metadata)
proof = cfrag.proof
proof_bytes = proof.to_bytes()
# A CorrectnessProof can be represented as
# the 228 total bytes of four Points (33 each) and three BigNums (32 each).
# TODO: Figure out final size for CorrectnessProofs
# assert len(proof_bytes) == (33 * 4) + (32 * 3) == 228
new_proof = CorrectnessProof.from_bytes(proof_bytes)
assert new_proof._point_e2 == proof._point_e2
assert new_proof._point_v2 == proof._point_v2
assert new_proof._point_kfrag_commitment == proof._point_kfrag_commitment
assert new_proof._point_kfrag_pok == proof._point_kfrag_pok
assert new_proof.bn_sig == proof.bn_sig
assert new_proof.kfrag_signature == proof.kfrag_signature
assert new_proof.metadata == proof.metadata
def test_cfrag_serialization_with_proof_but_no_metadata(alices_keys):
priv_key_alice, pub_key_alice = alices_keys
_unused_key, capsule = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_alice, 1, 2)
cfrag = pre.reencrypt(kfrags[0], capsule, provide_proof=True)
cfrag_bytes = cfrag.to_bytes()
proof = cfrag.proof
assert proof is not None
assert proof.metadata is None
# A CFrag can be represented as the 131 total bytes of three Points (33 each) and a CurveBN (32).
# TODO: Figure out final size for CFrags with proofs
#assert len(cfrag_bytes) == 33 + 33 + 33 + 32 == 131
new_cfrag = pre.CapsuleFrag.from_bytes(cfrag_bytes)
assert new_cfrag._point_e1 == cfrag._point_e1
assert new_cfrag._point_v1 == cfrag._point_v1
assert new_cfrag._bn_kfrag_id == cfrag._bn_kfrag_id
assert new_cfrag._point_noninteractive == cfrag._point_noninteractive
new_proof = new_cfrag.proof
assert new_proof is not None
assert new_proof._point_e2 == proof._point_e2
assert new_proof._point_v2 == proof._point_v2
assert new_proof._point_kfrag_commitment == proof._point_kfrag_commitment
assert new_proof._point_kfrag_pok == proof._point_kfrag_pok
assert new_proof._bn_kfrag_sig1 == proof._bn_kfrag_sig1
assert new_proof._bn_kfrag_sig2 == proof._bn_kfrag_sig2
assert new_proof._bn_sig == proof._bn_sig
assert new_proof.metadata is None
def test_alice_sends_fake_kfrag_to_ursula(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
plaintext = b'peace at dawn'
ciphertext, capsule = pre.encrypt(pub_key_alice, plaintext)
cleartext = pre.decrypt(capsule, priv_key_alice, ciphertext)
assert cleartext == plaintext
k_frags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
# Alice tries to frame the first Ursula by sending her a random kFrag
k_frags[0].bn_key = BigNum.gen_rand()
for k_frag in k_frags:
c_frag = pre.reencrypt(k_frag, capsule)
capsule.attach_cfrag(c_frag)
with pytest.raises(Exception):
_ = pre.decrypt(capsule, priv_key_bob, ciphertext, pub_key_alice)
def test_correctness_proof_serialization():
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
_unused_key, capsule = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, 1, 2)
# Example of potential metadata to describe the re-encryption request
metadata = b"This is an example of metadata for re-encryption request"
cfrag = pre.reencrypt(kfrags[0], capsule, metadata=metadata)
capsule.attach_cfrag(cfrag)
proof = cfrag.proof
proof_bytes = proof.to_bytes()
# A CorrectnessProof can be represented as
# the 228 total bytes of four Points (33 each) and three BigNums (32 each).
# TODO: Figure out final size for CorrectnessProofs
# assert len(proof_bytes) == (33 * 4) + (32 * 3) == 228
new_proof = CorrectnessProof.from_bytes(proof_bytes)
assert new_proof._point_e2 == proof._point_e2
assert new_proof._point_v2 == proof._point_v2
assert new_proof._point_kfrag_commitment == proof._point_kfrag_commitment
assert new_proof._point_kfrag_pok == proof._point_kfrag_pok
assert new_proof._bn_kfrag_sig1 == proof._bn_kfrag_sig1
assert new_proof._bn_kfrag_sig2 == proof._bn_kfrag_sig2
assert new_proof._bn_sig == proof._bn_sig
assert new_proof.metadata == proof.metadata
def test_capsule_as_dict_key(alices_keys):
priv_key_alice, pub_key_alice = alices_keys
plain_data = b'peace at dawn'
ciphertext, capsule = pre.encrypt(pub_key_alice, plain_data)
# We can use the capsule as a key, and successfully lookup using it.
some_dict = {capsule: "Thing that Bob wants to try per-Capsule"}
assert some_dict[capsule] == "Thing that Bob wants to try per-Capsule"
kfrags = pre.split_rekey(alices_keys.priv, alices_keys.pub, 1, 2)
cfrag = pre.reencrypt(kfrags[0], capsule)
capsule.attach_cfrag(cfrag)
cfrag = pre.reencrypt(kfrags[1], capsule)
capsule.attach_cfrag(cfrag)
# Even if we activate the capsule, it still serves as the same key.
cleartext = pre.decrypt(ciphertext, capsule, alices_keys.priv,
alices_keys.pub)
assert some_dict[capsule] == "Thing that Bob wants to try per-Capsule"
assert cleartext == plain_data
# And if we change the value for this key, all is still well.
some_dict[capsule] = "Bob has changed his mind."
assert some_dict[capsule] == "Bob has changed his mind."
assert len(some_dict.keys()) == 1
def test_challenge_response_serialization():
priv_key = pre.gen_priv()
pub_key = pre.priv2pub(priv_key)
_unused_key, capsule = pre._encapsulate(pub_key)
kfrags = pre.split_rekey(priv_key, pub_key, 1, 2)
cfrag = pre.reencrypt(kfrags[0], capsule)
capsule.attach_cfrag(cfrag)
ch_resp = pre.challenge(kfrags[0], capsule, cfrag)
ch_resp_bytes = ch_resp.to_bytes()
# A ChallengeResponse can be represented as
# the 228 total bytes of four Points (33 each) and three BigNums (32 each).
assert len(ch_resp_bytes) == (33 * 4) + (32 * 3) == 228
new_ch_resp = pre.ChallengeResponse.from_bytes(ch_resp_bytes)
assert new_ch_resp.point_eph_e2 == ch_resp.point_eph_e2
assert new_ch_resp.point_eph_v2 == ch_resp.point_eph_v2
assert new_ch_resp.point_kfrag_commitment == ch_resp.point_kfrag_commitment
assert new_ch_resp.point_kfrag_pok == ch_resp.point_kfrag_pok
assert new_ch_resp.bn_kfrag_sig1 == ch_resp.bn_kfrag_sig1
assert new_ch_resp.bn_kfrag_sig2 == ch_resp.bn_kfrag_sig2
assert new_ch_resp.bn_sig == ch_resp.bn_sig
def test_cheating_ursula_sends_garbage(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
# Bob
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
sym_key, capsule_alice = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
cfrags, metadata = [], []
for i, kfrag in enumerate(kfrags[:M]):
# Example of potential metadata to describe the re-encryption request
metadata_i = "This is an example of metadata for re-encryption request #{}"
metadata_i = metadata_i.format(i).encode()
cfrag = pre.reencrypt(kfrag, capsule_alice, metadata=metadata_i)
capsule_alice.attach_cfrag(cfrag)
cfrags.append(cfrag)
# Let's put random garbage in one of the cfrags
cfrags[0]._point_e1 = Point.gen_rand()
cfrags[0]._point_v1 = Point.gen_rand()
capsule_alice._reconstruct_shamirs_secret(pub_key_alice,
priv_key_bob) # activate capsule
with pytest.raises(pre.GenericUmbralError):
_unused_key = pre._decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule_alice)
assert not pre._verify_correctness(
capsule_alice,
cfrags[0],
pub_key_alice.point_key,
pub_key_bob.point_key,
)
# The response of cheating Ursula is in cfrags[0],
# so the rest of CFrags chould be correct:
for cfrag_i, metadata_i in zip(cfrags[1:], metadata[1:]):
assert pre._verify_correctness(
capsule_alice,
cfrag_i,
pub_key_alice.point_key,
pub_key_bob.point_key,
)
# Alternatively, we can try to open the capsule directly.
# We should get an exception with an attached list of incorrect cfrags
with pytest.raises(pre.UmbralCorrectnessError) as exception_info:
_ = pre._open_capsule(capsule_alice, priv_key_bob, pub_key_alice)
correctness_error = exception_info.value
assert cfrags[0] in correctness_error.offending_cfrags
assert len(correctness_error.offending_cfrags) == 1
def test_cheating_ursula_sends_garbage(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
# Bob
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
sym_key, capsule_alice = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
cfrags, challenges, metadata = [], [], []
for i, kfrag in enumerate(kfrags[:M]):
cfrag = pre.reencrypt(kfrag, capsule_alice)
# Example of potential metadata to describe the challenge request
metadata_i = {
'ursula_id': i,
'timestamp': time.time(),
'capsule': bytes(capsule_alice),
'cfrag': bytes(cfrag)
}
metadata_i = str(metadata_i).encode()
metadata.append(metadata_i)
challenge = pre._challenge(kfrag, capsule_alice, cfrag, metadata_i)
capsule_alice.attach_cfrag(cfrag)
assert pre._check_challenge(capsule_alice, cfrag, challenge,
pub_key_alice.point_key,
pub_key_bob.point_key, metadata_i)
cfrags.append(cfrag)
challenges.append(challenge)
# Let's put random garbage in one of the cfrags
cfrags[0].point_eph_e1 = Point.gen_rand()
cfrags[0].point_eph_v1 = Point.gen_rand()
capsule_alice._reconstruct_shamirs_secret(pub_key_alice,
priv_key_bob) # activate capsule
with pytest.raises(pre.GenericUmbralError):
sym_key2 = pre._decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule_alice)
assert not pre._check_challenge(capsule_alice, cfrags[0], challenges[0],
pub_key_alice.point_key,
pub_key_bob.point_key, metadata[0])
# The response of cheating Ursula is in capsules[0],
# so the rest of challenges chould be correct:
for i, challenge in enumerate(challenges[1:], 1):
cfrag = cfrags[i]
assert pre._check_challenge(capsule_alice, cfrag, challenge,
pub_key_alice.point_key,
pub_key_bob.point_key, metadata[i])
def test_cfrag_serialization_no_proof_no_metadata(alices_keys, bobs_keys):
delegating_privkey, signing_privkey = alices_keys
delegating_pubkey = delegating_privkey.get_pubkey()
_receiving_privkey, receiving_pubkey = bobs_keys
signer_alice = Signer(signing_privkey)
_unused_key, capsule = pre._encapsulate(delegating_pubkey.point_key)
kfrags = pre.split_rekey(delegating_privkey, signer_alice,
receiving_pubkey, 1, 2)
cfrag = pre.reencrypt(kfrags[0], capsule, provide_proof=False)
cfrag_bytes = cfrag.to_bytes()
proof = cfrag.proof
assert proof is None
curve = default_curve()
assert len(cfrag_bytes) == CapsuleFrag.expected_bytes_length(curve)
new_cfrag = pre.CapsuleFrag.from_bytes(cfrag_bytes)
assert new_cfrag._point_e1 == cfrag._point_e1
assert new_cfrag._point_v1 == cfrag._point_v1
assert new_cfrag._kfrag_id == cfrag._kfrag_id
assert new_cfrag._point_noninteractive == cfrag._point_noninteractive
new_proof = new_cfrag.proof
assert new_proof is None
def umbralize():
data = request.get_json()
resp = {}
sk_A = data['sk_A']
pk_B = data['pk_B']
M = data['M']
N = data['N']
sk_A = base64.b64decode(sk_A)
sk_A = keys.UmbralPrivateKey.from_bytes(sk_A)
pk_B = base64.b64decode(pk_B)
pk_B = keys.UmbralPublicKey.from_bytes(pk_B)
kfrags = pre.split_rekey(sk_A, pk_B, M, N)
bytekfrags = [
base64.encodestring(bytes(kfrag)).decode('ascii') for kfrag in kfrags
]
resp['bytekfrags'] = bytekfrags
return jsonify(resp)
def test_decryption_fails_when_it_expects_a_proof_and_there_isnt(N, M, alices_keys, bobs_keys):
"""Manually injects umbralparameters for multi-curve testing."""
delegating_privkey, signing_privkey = alices_keys
delegating_pubkey = delegating_privkey.get_pubkey()
signer = Signer(signing_privkey)
priv_key_bob, pub_key_bob = bobs_keys
plain_data = b'peace at dawn'
ciphertext, capsule = pre.encrypt(delegating_privkey.get_pubkey(), plain_data)
kfrags = pre.split_rekey(delegating_privkey, signer, pub_key_bob, M, N)
capsule.set_correctness_keys(delegating=delegating_privkey.get_pubkey(),
receiving=pub_key_bob,
verifying=signing_privkey.get_pubkey())
for kfrag in kfrags[:M]:
cfrag = pre.reencrypt(kfrag, capsule)
capsule.attach_cfrag(cfrag)
# Even thought we can successfully attach a CFrag, if the proof is lost
# (for example, it is chopped off a serialized CFrag or similar), then decrypt
# will still fail.
cfrag.proof = None
with pytest.raises(cfrag.NoProofProvided):
_cleartext = pre.decrypt(ciphertext, capsule, priv_key_bob)
def encrypt():
# Get data from request
json_data = json.loads(request.data.decode('utf-8'))
data = json_data["hash"].encode(
'utf-8') #, json_data['alice_pubkey'], json_data['alice_privkey']
alice_pubkey, alice_privkey = gen_alice()
# Encrypt some data
plaintext = data
ciphertext, capsule = pre.encrypt(alice_pubkey, plaintext)
alice_signing_privkey = keys.UmbralPrivateKey.gen_key()
alice_signing_pubkey = alice_signing_privkey.get_pubkey()
alice_signer = Signer(alice_signing_privkey)
# Perform split-rekey and grant re-encryption policy
alice_kfrags = pre.split_rekey(alice_privkey, alice_signer, bob_pubkey, 10,
20)
policy_id = mock_kms.grant(alice_kfrags)
alice_pubkey.from_bytes
response = {
"ciphertext": bytes_to_string(ciphertext),
"policy_id": policy_id,
"capsule": bytes_to_string(capsule.to_bytes()),
"alice_pubkey": bytes_to_string(alice_pubkey.to_bytes()),
"alice_signing_pubkey":
bytes_to_string(alice_signing_pubkey.to_bytes())
}
return jsonify(response)
def main(m, n, filenames):
files = [open(filename, 'w') for filename in filenames]
config.set_default_curve()
alice_privkey = keys.UmbralPrivateKey.gen_key()
alice_pubkey = alice_privkey.get_pubkey()
bob_privkey = keys.UmbralPrivateKey.gen_key()
bob_pubkey = bob_privkey.get_pubkey()
mock_kms = MockNetwork()
sys.stderr.write('Server with PID %s is ready to pipe messages.\n' % os.getpid())
for line in sys.stdin:
ciphertext, capsule = pre.encrypt(alice_pubkey, line.rstrip('\n').encode('utf8'))
alice_kfrags = pre.split_rekey(alice_privkey, bob_pubkey, m, n)
policy_id = mock_kms.grant(alice_kfrags)
bob_cfrags = mock_kms.reencrypt(policy_id, capsule, m)
bob_capsule = capsule
for cfrag in bob_cfrags:
bob_capsule.attach_cfrag(cfrag)
decrypted = pre.decrypt(ciphertext, bob_capsule, bob_privkey, alice_pubkey)
for file in files:
file.write('%s\n' % decrypted.decode('utf8'))
file.flush()
mock_kms.revoke(policy_id)
def test_m_of_n(N, M, alices_keys, bobs_keys):
delegating_privkey, signing_privkey = alices_keys
delegating_pubkey = delegating_privkey.get_pubkey()
signer = Signer(signing_privkey)
priv_key_bob, pub_key_bob = bobs_keys
params = delegating_privkey.params
sym_key, capsule = pre._encapsulate(delegating_pubkey)
capsule.set_correctness_keys(delegating=delegating_privkey.get_pubkey(),
receiving=pub_key_bob,
verifying=signing_privkey.get_pubkey())
kfrags = pre.split_rekey(delegating_privkey, signer, pub_key_bob, M, N)
for kfrag in kfrags:
assert kfrag.verify(signing_privkey.get_pubkey(), delegating_privkey.get_pubkey(), pub_key_bob)
for i, kfrag in enumerate(kfrags[:M]):
# Example of potential metadata to describe the re-encryption request
metadata = "This is an example of metadata for re-encryption request #{}"
metadata = metadata.format(i).encode()
cfrag = pre.reencrypt(kfrag, capsule, metadata=metadata)
capsule.attach_cfrag(cfrag)
assert cfrag.verify_correctness(capsule)
sym_key_from_capsule = pre._open_capsule(capsule, priv_key_bob)
assert sym_key == sym_key_from_capsule
def test_activated_capsule_serialization():
priv_key = pre.gen_priv()
pub_key = pre.priv2pub(priv_key)
_unused_key, capsule = pre._encapsulate(pub_key)
kfrags = pre.split_rekey(priv_key, pub_key, 1, 2)
cfrag = pre.reencrypt(kfrags[0], capsule)
capsule.attach_cfrag(cfrag)
capsule._reconstruct_shamirs_secret()
rec_capsule_bytes = capsule.to_bytes()
# An activated Capsule is:
# three points, representable as 33 bytes each (the original), and
# two points and a bignum (32 bytes) (the activated components), for 197 total.
assert len(rec_capsule_bytes) == (33 * 3) + (33 + 33 + 32)
new_rec_capsule = pre.Capsule.from_bytes(rec_capsule_bytes)
# Again, the same three perspectives on equality.
assert new_rec_capsule == capsule
assert new_rec_capsule.activated_components(
) == capsule.activated_components()
assert new_rec_capsule._point_eph_e_prime == capsule._point_eph_e_prime
assert new_rec_capsule._point_eph_v_prime == capsule._point_eph_v_prime
assert new_rec_capsule._point_noninteractive == capsule._point_noninteractive
def test_m_of_n(N, M, alices_keys, bobs_keys):
priv_key_alice, pub_key_alice = alices_keys
priv_key_bob, pub_key_bob = bobs_keys
sym_key, capsule = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
for kfrag in kfrags:
assert kfrag.verify(pub_key_alice.point_key, pub_key_bob.point_key)
for i, kfrag in enumerate(kfrags[:M]):
# Example of potential metadata to describe the re-encryption request
metadata = "This is an example of metadata for re-encryption request #{}"
metadata = metadata.format(i).encode()
cfrag = pre.reencrypt(kfrag, capsule, metadata=metadata)
capsule.attach_cfrag(cfrag)
assert pre._verify_correctness(
capsule,
cfrag,
pub_key_alice.point_key,
pub_key_bob.point_key,
)
# assert capsule.is_openable_by_bob() # TODO: Is it possible to check here if >= m cFrags have been attached?
sym_key_from_capsule = pre._open_capsule(capsule, priv_key_bob,
pub_key_alice)
assert sym_key == sym_key_from_capsule
def test_simple_api(N, M, curve=default_curve()):
"""Manually injects umbralparameters for multi-curve testing."""
params = UmbralParameters(curve=curve)
delegating_privkey = UmbralPrivateKey.gen_key(params=params)
delegating_pubkey = delegating_privkey.get_pubkey()
signing_privkey = UmbralPrivateKey.gen_key(params=params)
signing_pubkey = signing_privkey.get_pubkey()
signer = Signer(signing_privkey)
receiving_privkey = UmbralPrivateKey.gen_key(params=params)
receiving_pubkey = receiving_privkey.get_pubkey()
plain_data = b'peace at dawn'
ciphertext, capsule = pre.encrypt(delegating_pubkey, plain_data)
cleartext = pre.decrypt(ciphertext, capsule, delegating_privkey)
assert cleartext == plain_data
capsule.set_correctness_keys(delegating=delegating_pubkey,
receiving=receiving_pubkey,
verifying=signing_pubkey)
kfrags = pre.split_rekey(delegating_privkey, signer, receiving_pubkey, M, N)
for kfrag in kfrags:
cfrag = pre.reencrypt(kfrag, capsule)
capsule.attach_cfrag(cfrag)
reenc_cleartext = pre.decrypt(ciphertext, capsule, receiving_privkey)
assert reenc_cleartext == plain_data
def test_simple_api(N, M, curve=default_curve()):
"""Manually injects umbralparameters for multi-curve testing."""
params = UmbralParameters(curve=curve)
priv_key_alice = keys.UmbralPrivateKey.gen_key(params=params)
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key(params=params)
pub_key_bob = priv_key_bob.get_pubkey()
plain_data = b'peace at dawn'
ciphertext, capsule = pre.encrypt(pub_key_alice, plain_data, params=params)
cleartext = pre.decrypt(ciphertext, capsule, priv_key_alice, params=params)
assert cleartext == plain_data
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N, params=params)
for kfrag in kfrags:
cfrag = pre.reencrypt(kfrag, capsule, params=params)
capsule.attach_cfrag(cfrag)
reenc_cleartext = pre.decrypt(ciphertext,
capsule,
priv_key_bob,
pub_key_alice,
params=params)
assert reenc_cleartext == plain_data
def test_m_of_n(N, M, alices_keys, bobs_keys):
priv_key_alice, pub_key_alice = alices_keys
priv_key_bob, pub_key_bob = bobs_keys
sym_key, capsule = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
for kfrag in kfrags:
assert kfrag.verify(pub_key_alice.point_key, pub_key_bob.point_key)
for kfrag in kfrags[:M]:
cfrag = pre.reencrypt(kfrag, capsule)
capsule.attach_cfrag(cfrag)
ch = pre.challenge(kfrag, capsule, cfrag)
assert pre.check_challenge(capsule, cfrag, ch, pub_key_alice.point_key,
pub_key_bob.point_key)
# assert capsule.is_openable_by_bob() # TODO: Is it possible to check here if >= m cFrags have been attached?
# capsule.open(pub_bob, priv_bob, pub_alice)
capsule._reconstruct_shamirs_secret()
sym_key_from_capsule = pre.decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule)
assert sym_key == sym_key_from_capsule
def test_cheating_ursula_replays_old_reencryption(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
sym_key_alice1, capsule_alice1 = pre._encapsulate(pub_key_alice.point_key)
sym_key_alice2, capsule_alice2 = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
cfrags, metadata = [], []
for i, kfrag in enumerate(kfrags):
# Example of potential metadata to describe the re-encryption request
metadata_i = "This is an example of metadata for re-encryption request #{}"
metadata_i = metadata_i.format(i).encode()
if i == 0:
# Let's put the re-encryption of a different Alice ciphertext
cfrag = pre.reencrypt(kfrag, capsule_alice2, metadata=metadata_i)
else:
cfrag = pre.reencrypt(kfrag, capsule_alice1, metadata=metadata_i)
capsule_alice1.attach_cfrag(cfrag)
cfrags.append(cfrag)
# Let's activate the capsule
capsule_alice1._reconstruct_shamirs_secret(pub_key_alice, priv_key_bob)
with pytest.raises(pre.GenericUmbralError):
sym_key = pre._decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule_alice1)
assert not cfrags[0].verify_correctness(
capsule_alice1,
pub_key_alice,
pub_key_bob,
)
# The response of cheating Ursula is in cfrags[0],
# so the rest of CFrags should be correct:
for cfrag_i, metadata_i in zip(cfrags[1:], metadata[1:]):
assert cfrag_i.verify_correctness(
capsule_alice1,
pub_key_alice,
pub_key_bob,
)
# Alternatively, we can try to open the capsule directly.
# We should get an exception with an attached list of incorrect cfrags
with pytest.raises(pre.UmbralCorrectnessError) as exception_info:
_ = pre._open_capsule(capsule_alice1, priv_key_bob, pub_key_alice)
correctness_error = exception_info.value
assert cfrags[0] in correctness_error.offending_cfrags
assert len(correctness_error.offending_cfrags) == 1
def test_cheating_ursula_replays_old_reencryption(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
sym_key_alice1, capsule_alice1 = pre._encapsulate(pub_key_alice.point_key)
sym_key_alice2, capsule_alice2 = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
cfrags, challenges = [], []
for index, kfrag in enumerate(kfrags):
if index == 0:
# Let's put the re-encryption of a different Alice ciphertext
cfrag = pre.reencrypt(kfrag, capsule_alice2)
else:
cfrag = pre.reencrypt(kfrag, capsule_alice1)
metadata = ("Challenge metadata: index {}".format(index)).encode()
challenge = pre._challenge(kfrag, capsule_alice1, cfrag, metadata)
capsule_alice1.attach_cfrag(cfrag)
challenges.append(challenge)
cfrags.append(cfrag)
# Let's activate the capsule
capsule_alice1._reconstruct_shamirs_secret(pub_key_alice, priv_key_bob)
with pytest.raises(pre.GenericUmbralError):
sym_key = pre._decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule_alice1)
metadata = b"Challenge metadata: index 0"
assert not pre._check_challenge(capsule_alice1,
cfrags[0],
challenges[0],
pub_key_alice.point_key,
pub_key_bob.point_key,
metadata
)
# The response of cheating Ursula is in capsules[0],
# so the rest of challenges chould be correct:
for i, challenge in enumerate(challenges[1:], 1):
cfrag = cfrags[i]
metadata = ("Challenge metadata: index {}".format(i)).encode()
assert pre._check_challenge(capsule_alice1,
cfrag,
challenge,
pub_key_alice.point_key,
pub_key_bob.point_key,
metadata
)
def test_wrong_N_M_in_split_rekey(N, M, alices_keys, bobs_keys):
delegating_privkey, signing_privkey = alices_keys
signer = Signer(signing_privkey)
_receiving_privkey, receiving_pubkey = bobs_keys
with pytest.raises(ValueError):
_kfrags = pre.split_rekey(delegating_privkey, signer, receiving_pubkey,
M, N)
def __setup():
delegating_privkey, signer, receiving_pubkey, ciphertext, capsule = __standard_encryption_api(
)
kfrags = pre.split_rekey(delegating_privkey, signer, receiving_pubkey,
m, n)
one_kfrag, *remaining_kfrags = kfrags
args, kwargs = tuple(), {"kfrag": one_kfrag, "capsule": capsule},
return args, kwargs
def kfrags(alices_keys, bobs_keys):
delegating_privkey, signing_privkey = alices_keys
delegating_pubkey = delegating_privkey.get_pubkey()
signer_alice = Signer(signing_privkey)
receiving_privkey, receiving_pubkey = bobs_keys
yield pre.split_rekey(delegating_privkey, signer_alice, receiving_pubkey,
6, 10)
def test_cheating_ursula_replays_old_reencryption(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
sym_key_alice1, capsule_alice1 = pre._encapsulate(pub_key_alice.point_key)
sym_key_alice2, capsule_alice2 = pre._encapsulate(pub_key_alice.point_key)
kfrags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
cfrags, challenges, metadata = [], [], []
for i, kfrag in enumerate(kfrags):
if i == 0:
# Let's put the re-encryption of a different Alice ciphertext
cfrag = pre.reencrypt(kfrag, capsule_alice2)
else:
cfrag = pre.reencrypt(kfrag, capsule_alice1)
# Example of potential metadata to describe the challenge request
metadata_i = {
'ursula_id': i,
'timestamp': time.time(),
'capsule': bytes(capsule_alice1),
'cfrag': bytes(cfrag)
}
metadata.append(str(metadata_i).encode())
challenge = pre._challenge(kfrag, capsule_alice1, cfrag, metadata[i])
capsule_alice1.attach_cfrag(cfrag)
challenges.append(challenge)
cfrags.append(cfrag)
# Let's activate the capsule
capsule_alice1._reconstruct_shamirs_secret(pub_key_alice, priv_key_bob)
with pytest.raises(pre.GenericUmbralError):
sym_key = pre._decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule_alice1)
assert not pre._check_challenge(capsule_alice1, cfrags[0], challenges[0],
pub_key_alice.point_key,
pub_key_bob.point_key, metadata[0])
# The response of cheating Ursula is in capsules[0],
# so the rest of challenges should be correct:
for i, challenge in enumerate(challenges[1:], 1):
cfrag = cfrags[i]
assert pre._check_challenge(capsule_alice1, cfrag, challenge,
pub_key_alice.point_key,
pub_key_bob.point_key, metadata[i])
def reencrypt(self, receiver_public_key: bytes) -> List[pre.KFrag]:
receiver_pubkey = keys.UmbralPublicKey.from_bytes(receiver_public_key)
kfrags = pre.split_rekey(delegating_privkey=self.private_key,
signer=self.signer,
receiving_pubkey=receiver_pubkey,
threshold=10,
N=20)
return kfrags
def test_bad_capsule_fails_reencryption(alices_keys):
priv_key_alice, pub_key_alice = alices_keys
kfrags = pre.split_rekey(priv_key_alice, pub_key_alice, 1, 2)
bollocks_capsule = Capsule(point_e=Point.gen_rand(),
point_v=Point.gen_rand(),
bn_sig=CurveBN.gen_rand())
with pytest.raises(Capsule.NotValid):
pre.reencrypt(kfrags[0], bollocks_capsule)
def encrypt_message(receiver_pub_key, plaintext, sender_priv_key):
ciphertext, capsule = pre.encrypt(receiver_pub_key, plaintext)
kfrags = pre.split_rekey(sender_priv_key, receiver_pub_key, 10, 20)
for k in kfrags:
cfrag = pre.reencrypt(kfrag, capsule)
capsule.attach_cfrag(cfrag)
return ciphertext, capsule
def test_cheating_ursula_replays_old_reencryption(N, M):
priv_key_alice = keys.UmbralPrivateKey.gen_key()
pub_key_alice = priv_key_alice.get_pubkey()
priv_key_bob = keys.UmbralPrivateKey.gen_key()
pub_key_bob = priv_key_bob.get_pubkey()
sym_key_alice1, capsule_alice1 = pre._encapsulate(pub_key_alice.point_key)
sym_key_alice2, capsule_alice2 = pre._encapsulate(pub_key_alice.point_key)
k_frags = pre.split_rekey(priv_key_alice, pub_key_bob, M, N)
c_frags, challenges = [], []
for index, k_frag in enumerate(k_frags):
if index == 0:
# Let's put the re-encryption of a different Alice ciphertext
c_frag = pre.reencrypt(k_frag, capsule_alice2)
else:
c_frag = pre.reencrypt(k_frag, capsule_alice1)
challenge = pre.challenge(k_frag, capsule_alice1, c_frag)
capsule_alice1.attach_cfrag(c_frag)
challenges.append(challenge)
c_frags.append(c_frag)
capsule_alice1._reconstruct_shamirs_secret() # activate capsule
with pytest.raises(pre.GenericUmbralError):
sym_key = pre.decapsulate_reencrypted(pub_key_bob.point_key,
priv_key_bob.bn_key,
pub_key_alice.point_key,
capsule_alice1)
assert not sym_key == sym_key_alice1
assert not pre.check_challenge(
capsule_alice1,
c_frags[0],
challenges[0],
pub_key_alice.point_key,
pub_key_bob.point_key,
)
# The response of cheating Ursula is in capsules[0],
# so the rest of challenges chould be correct:
for (c_frag, ch) in zip(c_frags[1:], challenges[1:]):
assert pre.check_challenge(
capsule_alice1,
c_frag,
ch,
pub_key_alice.point_key,
pub_key_bob.point_key,
)
