From 550dfd44cbf98b3b8d0348303b32e7ac1fa8b4b8 Mon Sep 17 00:00:00 2001
From: Mark Qvist <mark@unsigned.io>
Date: Tue, 8 Mar 2022 00:38:51 +0100
Subject: [PATCH] Improved cryptography API compatibility

---
 RNS/Identity.py             | 12 ++++++++++--
 RNS/Link.py                 |  7 ++++++-
 RNS/_version.py             |  2 +-
 RNS/vendor/platformutils.py |  7 +++++++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/RNS/Identity.py b/RNS/Identity.py
index a5bd059..b241cb6 100644
--- a/RNS/Identity.py
+++ b/RNS/Identity.py
@@ -14,6 +14,8 @@ from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey, X
 from cryptography.hazmat.primitives.kdf.hkdf import HKDF
 from cryptography.fernet import Fernet
 
+cio_default_backend = default_backend()
+
 class Identity:
     """
     This class is used to manage identities in Reticulum. It provides methods
@@ -392,11 +394,14 @@ class Identity:
             )
 
             shared_key = ephemeral_key.exchange(self.pub)
-            derived_key = derived_key = HKDF(
+            
+            # TODO: Improve this re-allocation of HKDF
+            derived_key = HKDF(
                 algorithm=hashes.SHA256(),
                 length=32,
                 salt=self.get_salt(),
                 info=self.get_context(),
+                backend=cio_default_backend,
             ).derive(shared_key)
 
             fernet = Fernet(base64.urlsafe_b64encode(derived_key))
@@ -424,11 +429,14 @@ class Identity:
                     peer_pub = X25519PublicKey.from_public_bytes(peer_pub_bytes)
 
                     shared_key = self.prv.exchange(peer_pub)
-                    derived_key = derived_key = HKDF(
+
+                    # TODO: Improve this re-allocation of HKDF
+                    derived_key = HKDF(
                         algorithm=hashes.SHA256(),
                         length=32,
                         salt=self.get_salt(),
                         info=self.get_context(),
+                        backend=cio_default_backend,
                     ).derive(shared_key)
 
                     fernet = Fernet(base64.urlsafe_b64encode(derived_key))
diff --git a/RNS/Link.py b/RNS/Link.py
index 9386b84..98a4082 100644
--- a/RNS/Link.py
+++ b/RNS/Link.py
@@ -15,6 +15,8 @@ import RNS
 
 import traceback
 
+cio_default_backend = default_backend()
+
 class LinkCallbacks:
     def __init__(self):
         self.link_established = None
@@ -199,11 +201,14 @@ class Link:
     def handshake(self):
         self.status = Link.HANDSHAKE
         self.shared_key = self.prv.exchange(self.peer_pub)
+
+        # TODO: Improve this re-allocation of HKDF
         self.derived_key = HKDF(
             algorithm=hashes.SHA256(),
             length=32,
             salt=self.get_salt(),
             info=self.get_context(),
+            backend=cio_default_backend,
         ).derive(self.shared_key)
 
     def prove(self):
@@ -1064,4 +1069,4 @@ class RequestReceiptCallbacks:
     def __init__(self):
         self.response = None
         self.failed   = None
-        self.progress = None
\ No newline at end of file
+        self.progress = None
diff --git a/RNS/_version.py b/RNS/_version.py
index 26eaa49..e19434e 100644
--- a/RNS/_version.py
+++ b/RNS/_version.py
@@ -1 +1 @@
-__version__ = "0.3.3"
\ No newline at end of file
+__version__ = "0.3.3"
diff --git a/RNS/vendor/platformutils.py b/RNS/vendor/platformutils.py
index cb322d0..d8cc705 100644
--- a/RNS/vendor/platformutils.py
+++ b/RNS/vendor/platformutils.py
@@ -36,3 +36,10 @@ def platform_checks():
             RNS.log("On Windows, Reticulum requires Python 3.8 or higher.", RNS.LOG_ERROR)
             RNS.log("Please update Python to run Reticulum.", RNS.LOG_ERROR)
             RNS.panic()
+
+def cryptography_old_api():
+    import cryptography
+    if cryptography.__version__ == "2.8":
+        return True
+    else:
+        return False
\ No newline at end of file