Improvements and fixes

secmem.py

@@ -0,0 +1,61 @@
+import ctypes
+import ctypes.util
+import sys
+
+if sys.platform == "darwin":
+    _libc = ctypes.CDLL("libSystem.B.dylib")
+else:
+    _libc = ctypes.CDLL(ctypes.util.find_library("c"))
+
+_mlock = _libc.mlock
+_mlock.argtypes = [ctypes.c_void_p, ctypes.c_size_t]
+_mlock.restype = ctypes.c_int
+
+_munlock = _libc.munlock
+_munlock.argtypes = [ctypes.c_void_p, ctypes.c_size_t]
+_munlock.restype = ctypes.c_int
+
+
+def _addr(buf: bytearray) -> int:
+    return ctypes.addressof((ctypes.c_char * len(buf)).from_buffer(buf))
+
+
+def mlock(buf: bytearray):
+    if len(buf) > 0:
+        _mlock(_addr(buf), len(buf))
+
+
+def munlock(buf: bytearray):
+    if len(buf) > 0:
+        _munlock(_addr(buf), len(buf))
+
+
+def wipe(buf: bytearray):
+    for i in range(len(buf)):
+        buf[i] = 0
+
+
+class SecureBuffer:
+    __slots__ = ("_buf",)
+
+    def __init__(self, data: bytes | bytearray):
+        self._buf = bytearray(data)
+        mlock(self._buf)
+
+    @property
+    def raw(self) -> bytearray:
+        return self._buf
+
+    def __len__(self):
+        return len(self._buf)
+
+    def __bytes__(self):
+        return bytes(self._buf)
+
+    def __del__(self):
+        self.close()
+
+    def close(self):
+        if self._buf:
+            wipe(self._buf)
+            munlock(self._buf)