refactors project structure

pisa/encrypted_blob.py

@@ -0,0 +1,30 @@
+from binascii import unhexlify, hexlify
+from hashlib import sha256
+from cryptography.hazmat.primitives.ciphers.aead import AESGCM
+
+
+class EncryptedBlob:
+    def __init__(self, data):
+        self.data = data
+
+    def decrypt(self, key, debug, logging):
+        # master_key = H(tx_id | tx_id)
+        master_key = sha256(key + key).digest()
+
+        # The 16 MSB of the master key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
+        sk = master_key[:16]
+        nonce = master_key[16:]
+
+        if debug:
+            logging.info("[Watcher] creating new blob")
+            logging.info("[Watcher] master key: {}".format(hexlify(master_key).decode()))
+            logging.info("[Watcher] sk: {}".format(hexlify(sk).decode()))
+            logging.info("[Watcher] nonce: {}".format(hexlify(nonce).decode()))
+            logging.info("[Watcher] encrypted_blob: {}".format(self.data))
+
+        # Decrypt
+        aesgcm = AESGCM(sk)
+        data = unhexlify(self.data.encode())
+        raw_tx = aesgcm.decrypt(nonce=nonce, data=data, associated_data=None)
+
+        return raw_tx