fix CryptDeriveKey for RC4 & MD5

fixes crappycrypto#5
zerog2k · Dec 11, 2022 · 7cea1d8 · 7cea1d8
1 parent 7b87ba7
commit 7cea1d8
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/wincrypto/api.py b/wincrypto/api.py
@@ -102,4 +102,7 @@ def CryptDeriveKey(hash_alg, algid):
     else:
         key = hash_val
     key = key[:alg_class.key_len]
-    return alg_class(key)
+    if algid == CALG_RC4:
+        # MSFT RC4 only uses 5 bytes of hash, zero padded
+        key = key[:5] + bytes(11)    
+    return alg_class(key)