change encrypted channel logs to use RSA -> AES (CBC)

closes #248

1 files changed, 30 insertions, 7 deletions

diff --git a/bin/bitbot-log b/bin/bitbot-log
index da6d0c8b..959e6ca7 100755
--- a/bin/bitbot-log
+++ b/bin/bitbot-log
@@ -15,13 +15,26 @@ import base64
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives import hashes
-from cryptography.hazmat.primitives.asymmetric import padding
+from cryptography.hazmat.primitives.asymmetric import padding as a_padding
 
-def a_decrypt(key, data):
-    out = key.decrypt(base64.b64decode(data), padding.OAEP(
-        mgf=padding.MGF1(algorithm=hashes.SHA256()),
+def rsa_decrypt(key, data):
+    return key.decrypt(base64.b64decode(data), a_padding.OAEP(
+        mgf=a_padding.MGF1(algorithm=hashes.SHA256()),
         algorithm=hashes.SHA256(), label=None))
-    return out.decode("utf8")
+
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+from cryptography.hazmat.primitives import padding
+
+def aes_decrypt(key: bytes, data_str: str):
+    data_bytes = base64.b64decode(data_str)
+    iv, data_bytes = data_bytes[:16], data_bytes[16:]
+
+    decryptor = Cipher(algorithms.AES(key), modes.CBC(iv),
+        backend=default_backend()).decryptor()
+    plain = decryptor.update(data_bytes)+decryptor.finalize()
+
+    unpadder = padding.PKCS7(256).unpadder()
+    return (unpadder.update(plain)+unpadder.finalize()).decode("utf8")
 
 with open(args.key, "rb") as key_file:
     key_content = key_file.read()
@@ -32,7 +45,17 @@ with open(args.log) as log_file:
     lines = log_file.read().split("\n")
 lines = filter(None, lines)
 
+symm_key = None
 for line in lines:
+    printable = None
     if line[0] == "\x02":
-        line = a_decrypt(key, line[1:])
-    print(line)
+        printable = rsa_decrypt(key, line[1:]).decode("utf8")
+    elif line[0] == "\x03":
+        symm_key = rsa_decrypt(key, line[1:])
+    elif line[0] == "\x04":
+        printable = aes_decrypt(symm_key, line[1:])
+    else:
+        printable = line
+
+    if not printable == None:
+        print(printable)