Fix loading ssl library on MacOSX 10.15; Try to load libeay32 only on Win

Only relevant for historical signatures, as openssl is not used
otherwise. But it is used, for example, when VerifyScript is called
without specifyng any of _STRICT_ENCODING_FLAGS

Author: dgpv

bitcointx/core/key.py

@@ -23,6 +23,7 @@
 import struct
 import ctypes
 import ctypes.util
+import platform
 import hashlib
 import warnings
 from abc import abstractmethod
@@ -80,7 +81,21 @@ def _check_res_openssl_void_p(val, func, args): # type: ignore
 def load_openssl_library(path: Optional[str] = None) -> Optional[ctypes.CDLL]:
 
     if path is None:
-        path = ctypes.util.find_library('ssl') or 'libeay32'
+        path_generic = ctypes.util.find_library('ssl')
+        if platform.system() == 'Darwin':
+            # Fix for bug in MacOSX 10.15 where libssl is not a real
+            # library, and causes SIGABRT on load.
+            # libssl.35 should be the most compatible lib available there.
+            path = ctypes.util.find_library('ssl.35') or path_generic
+        elif platform.system() == 'Windows':
+            path = path_generic or 'libeay32'
+        else:
+            path = path_generic
+
+        if path is None:
+            raise ImportError(
+                "ssl library is required for non-strict signature "
+                "verification, but it was not found")
 
     try:
         handle: Optional[ctypes.CDLL] = ctypes.cdll.LoadLibrary(path)

release-notes.md

@@ -2,7 +2,9 @@
 
 ## v1.1.1.dev0
 
-...
+Fixes for openssl loading (only relevant for historical signatures:
+    - Fix issue with libssl on MacOSX 10.15. by trying to load `libssl.35` first
+    - The `libeay32` library is only tried to be loaded on Windows platform
 
 ## v1.1.0