def download(data_hash, sender, signature, decryption_key):
"""
Check if data_hash is valid SHA-256 hash matched with existing file.
Download stored file from the Node.
:param data_hash: SHA-256 hash for needed file
:param sender: file sender's BitCoin address
:param signature: data signature
:param decryption_key: key for decrypt stored file
:return: file data generator
"""
node = app.config['NODE']
checker = Checker(data_hash, sender, signature)
if not (signature and sender):
checks_result_unauthenticated = checker.check_all('hash', 'blacklist',
'file')
if checks_result_unauthenticated:
return checks_result_unauthenticated
if checker.file.role not in ('001', '101'):
return ERR_TRANSFER['INVALID_SIGNATURE']
else:
checks_result_authenticated = checker.check_all('hash', 'blacklist',
'file', 'signature')
if checks_result_authenticated:
return checks_result_authenticated
file = checker.file
if node.limits['outgoing'] is not None and (
file.size > node.limits['outgoing'] - node.current['outgoing']
):
return ERR_TRANSFER['LIMIT_REACHED']
file_path = os.path.join(app.config['UPLOAD_FOLDER'], data_hash)
if not os.path.exists(file_path):
return ERR_TRANSFER['LOST_FILE']
if decryption_key:
if file.role[2] == '1':
try:
decryption_key = binascii.unhexlify(decryption_key)
# test on decryption_key validness
test_decrypt_data_generator = convergence.decrypt_generator(
file_path, decryption_key)
next(test_decrypt_data_generator)
decrypt_data_generator = convergence.decrypt_generator(
file_path, decryption_key)
return decrypt_data_generator
except (binascii.Error, ValueError):
return ERR_TRANSFER['INVALID_DECRYPTION_KEY']
else:
return ERR_TRANSFER['NOT_FOUND']
with open(os.path.join(app.config['UPLOAD_FOLDER'], data_hash), 'rb') as f:
returned_data = f.read()
return returned_data
def test_streaming_decryption(self):
plaintext = self.contents(self.sample1)
key = convergence.encrypt_file_inline(self.sample1, "super secret")
decrypted = "".encode()
for chunk in convergence.decrypt_generator(self.sample1, key):
decrypted += chunk
self.assertEqual(plaintext, decrypted)
def test_streaming_authenticated_decryption(self):
plaintext = self.contents(self.sample1)
k,h = convergence.encrypt_file_inline(self.sample1, "test secret", True)
decrypted = b""
for chunk in convergence.decrypt_generator(self.sample1, k, h):
decrypted += chunk
self.assertEqual(plaintext,decrypted)
def test_streaming_decryption(self):
plaintext = self.contents(self.sample1)
key = convergence.encrypt_file_inline(self.sample1, "super secret")
decrypted = "".encode()
for chunk in convergence.decrypt_generator(self.sample1, key):
decrypted += chunk
self.assertEqual(plaintext, decrypted)
def test_streaming_authenticated_decryption_failed(self):
k,h = convergence.encrypt_file_inline(self.sample1, "test secret", True)
# modify file
with open(self.sample1, "ab") as f:
f.write("data added!\n".encode())
decrypted = b""
with self.assertRaises(AuthenticationError) as ex:
for chunk in convergence.decrypt_generator(self.sample1, k, h):
decrypted += chunk
self.assertEqual(str(ex.exception),"Hash Message Authentication Code invalid.")
