Create common package

Moves cryptographer to common. Also adds constants and defines the leghtn of the locator to avoid hardcoding it in almost every file

pisa/api.py

@@ -8,17 +8,12 @@ from pisa.logger import Logger
 from pisa.inspector import Inspector
 from pisa.appointment import Appointment
 from pisa.block_processor import BlockProcessor
+from common.constants import HTTP_OK, HTTP_BAD_REQUEST, HTTP_SERVICE_UNAVAILABLE
 
 
 # ToDo: #5-add-async-to-api
 app = Flask(__name__)
-
-HTTP_OK = 200
-HTTP_BAD_REQUEST = 400
-HTTP_SERVICE_UNAVAILABLE = 503
-
 logger = Logger("API")
-
 watcher = None
 
 

pisa/cryptographer.py

@@ -1,51 +0,0 @@
-from hashlib import sha256
-from binascii import unhexlify, hexlify
-from cryptography.exceptions import InvalidTag
-from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
-
-from pisa.logger import Logger
-
-logger = Logger("Cryptographer")
-
-
-# FIXME: Cryptographer is assuming AES-128-GCM and SHA256 since they are the only pair accepted by the encrypted blob
-#   and the only pair programmed so far.
-class Cryptographer:
-    @staticmethod
-    # ToDo: #20-test-tx-decrypting-edge-cases
-    def decrypt(encrypted_blob, key, rtype="hex"):
-        if rtype not in ["hex", "bytes"]:
-            raise ValueError("Wrong return type. Return type must be 'hex' or 'bytes'")
-
-        if len(encrypted_blob.data) % 2:
-            logger.info(
-                "Incorrect (Odd-length) value to be decrypted.", encrypted_blob=encrypted_blob.data, dispute_txid=key
-            )
-            return None
-
-        # sk is the H(txid) (32-byte) and nonce is set to 0 (12-byte)
-        sk = sha256(unhexlify(key)).digest()
-        nonce = bytearray(12)
-
-        logger.info(
-            "Creating new blob.",
-            sk=hexlify(sk).decode(),
-            nonce=hexlify(nonce).decode(),
-            encrypted_blob=encrypted_blob.data,
-        )
-
-        # Decrypt
-        cipher = ChaCha20Poly1305(sk)
-        data = unhexlify(encrypted_blob.data.encode())
-
-        try:
-            blob = cipher.decrypt(nonce=nonce, data=data, associated_data=None)
-
-            # Change the blob encoding to hex depending on the rtype (default)
-            if rtype == "hex":
-                blob = hexlify(blob).decode("utf8")
-
-        except InvalidTag:
-            blob = None
-
-        return blob

pisa/inspector.py

@@ -8,6 +8,8 @@ from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.serialization import load_pem_public_key
 from cryptography.exceptions import InvalidSignature
 
+from common.constants import LOCATOR_LEN_HEX
+
 from pisa import errors
 import pisa.conf as conf
 from pisa.logger import Logger
@@ -64,7 +66,7 @@ class Inspector:
             rcode = errors.APPOINTMENT_WRONG_FIELD_TYPE
             message = "wrong locator data type ({})".format(type(locator))
 
-        elif len(locator) != 32:
+        elif len(locator) != LOCATOR_LEN_HEX:
             rcode = errors.APPOINTMENT_WRONG_FIELD_SIZE
             message = "wrong locator size ({})".format(len(locator))
             # TODO: #12-check-txid-regexp