1 files changed, 38 insertions, 0 deletions
diff --git a/samloader/auth.py b/samloader/auth.py
new file mode 100644
index 0000000..d2c6257
--- /dev/null
+++ b/samloader/auth.py
@@ -0,0 +1,38 @@
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2020 Nayil Mukhametshin
+
+# FUS authentication functions (decrypting nonce, calculating auth token)
+
+from Crypto.Cipher import AES
+import base64
+import requests
+
+KEY_1 = "hqzdurufm2c8mf6bsjezu1qgveouv7c7"
+KEY_2 = "w13r4cvf4hctaujv"
+
+unpad = lambda d: d[:-d[-1]]
+pad = lambda d: d + bytes([16 - (len(d) % 16)]) * (16 - (len(d) % 16))
+
+def aes_encrypt(inp, key):
+    cipher = AES.new(key, AES.MODE_CBC, key[:16])
+    return cipher.encrypt(pad(inp))
+
+def aes_decrypt(inp, key):
+    cipher = AES.new(key, AES.MODE_CBC, key[:16])
+    return unpad(cipher.decrypt(inp))
+
+def getfkey(inp):
+    key = ""
+    for i in range(16):
+        key += KEY_1[inp[i]]
+    key += KEY_2
+    return key.encode()
+
+def getauth(nonce):
+    keydata = [ord(c) % 16 for c in nonce]
+    fkey = getfkey(keydata)
+    return base64.b64encode(aes_encrypt(nonce.encode(), fkey)).decode()
+
+def decryptnonce(inp):
+    nonce = aes_decrypt(base64.b64decode(inp), KEY_1.encode()).decode()
+    return nonce