tightened OS crypt backend tests

* split os_crypt tests into separate mixin
* tests now require os_crypt backends to detect some simple incorrect returns from crypt()
	- e.g. returning wrong ident prefix, wrong size, etc
	- added relevant asserts to all os_crypt backends
* tests now check if platform crypt detection is functioning correctly
  via platform_crypt_support dict in tests.

1 files changed, 6 insertions, 3 deletions

diff --git a/passlib/handlers/des_crypt.py b/passlib/handlers/des_crypt.py
index 41e132a..df7683a 100644
--- a/passlib/handlers/des_crypt.py
+++ b/passlib/handlers/des_crypt.py
@@ -219,7 +219,8 @@ class des_crypt(uh.HasManyBackends, uh.HasSalt, uh.GenericHandler):
         # no official policy since des-crypt predates unicode
         hash = safe_crypt(secret, self.salt)
         if hash:
-            return hash[2:]
+            assert hash.startswith(self.salt) and len(hash) == 4
+            return hash[-2:]
         else:
             return self._calc_checksum_builtin(secret)
 
@@ -331,9 +332,11 @@ class bsdi_crypt(uh.HasManyBackends, uh.HasRounds, uh.HasSalt, uh.GenericHandler
         return raw_ext_crypt(secret, self.rounds, self.salt.encode("ascii")).decode("ascii")
 
     def _calc_checksum_os_crypt(self, secret):
-        hash = safe_crypt(secret, self.to_string())
+        config = self.to_string()
+        hash = safe_crypt(secret, config)
         if hash:
-            return hash[9:]
+            assert hash.startswith(config[:9]) and len(hash) == 20
+            return hash[-11:]
         else:
             return self._calc_checksum_builtin(secret)