1 files changed, 82 insertions, 0 deletions
diff --git a/cffi_random.py b/cffi_random.py
new file mode 100644
index 0000000..5f62e43
--- /dev/null
+++ b/cffi_random.py
@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+
+import sys
+from typing import Optional
+
+from cffi import FFI
+
+class RandError(RuntimeError):
+    pass
+
+ffi = FFI()
+ffi.cdef('''
+    void RAND_seed(const void *buf, int num);
+
+    void RAND_add(const void *buf, int num, double entropy);
+
+    int  RAND_status(void);
+
+    int  RAND_event(unsigned int iMsg, void* wParam, void* lParam);
+    void RAND_screen(void);
+
+    int RAND_bytes(unsigned char *buf, int num);
+
+    int RAND_pseudo_bytes(unsigned char *buf, int num);
+
+    const char *ERR_reason_error_string(unsigned long);
+
+    unsigned long ERR_get_error(void);
+''')
+
+lib = ffi.dlopen('crypto')
+
+def rand_add(buf: bytes, num: int, entropy: float) -> None:
+    assert isinstance(entropy, float)
+    lib.RAND_add(buf, num, entropy)
+
+def rand_seed(buf: bytes, num: int) -> None:
+    lib.RAND_seed(buf, num)
+
+def rand_status() -> int:
+    return lib.RAND_status()
+
+def rand_event(iMsg: int, wParam: int, lParam: int) -> Optional[int]:
+    if sys.platform == 'win32':
+        return lib.RAND_event(iMsg, wParam, lParam)
+    else:
+        return None
+
+def rand_screen() -> None:
+    if sys.platform == 'win32':
+        lib.RAND_screen()
+
+def rand_bytes(n: int = 8) -> bytes:
+    buf = ffi.new('unsigned char buf[{:d}]'.format(n))
+    ret = lib.RAND_bytes(buf, n)
+    if ret == 1:
+        return bytes(buf)
+    elif ret == 0:
+        RandError("Not enough randomness.")
+    elif ret == -1:
+        RandError("Not supported by the current RAND method.")
+    else:
+        err_msg = lib.ERR_reason_error_string(lib.ERR_get_error())
+        if err_msg is not None:
+            RandError(err_msg)
+        else:
+            RandError("Unknown error in function RAND_bytes")
+
+def rand_pseudo_bytes(n: int) -> bytes:
+    blob = ffi.new('unsigned char buf[{:d}]'.format(n))
+    ret = lib.RAND_pseudo_bytes(blob, n)
+
+    if ret == -1:
+        RandError("Not supported by the current RAND method.")
+    elif ret in [0, 1]:
+        return (blob, ret)
+    else:
+        RandError("Unknown error in RAND_pseudo_bytes")
+
+
+if __name__=='__main__':
+    print(rand_bytes())