leading zeros are missing from result of pbkdf2

[bhuztez]

Here is an example.

>>> import hashlib
>>> from django.utils import crypto
>>> from M2Crypto import EVP
>>> EVP.pbkdf2(chr(186), 'salt', 1, 20)
'\x00S\xd3\xb9\x1a\x7f\x1eT\xef\xfe\xbdmhw\x1e\x8an\x0b,['
>>> crypto.pbkdf2(chr(186), 'salt', 1, 20, digest=hashlib.sha1)
'S\xd3\xb9\x1a\x7f\x1eT\xef\xfe\xbdmhw\x1e\x8an\x0b,['
>>> 

[Aymeric Augustin]

Confirmed with this totally over-engineered snippet:

>>> import difflib
>>> import hashlib
>>> from django.utils import crypto
>>> from M2Crypto import EVP
>>> for i in range(255):
...     expected = repr(EVP.pbkdf2(chr(i), 'salt', 1, 20))
...     actual = repr(crypto.pbkdf2(chr(i), 'salt', 1, 20, digest=hashlib.sha1))
...     if expected != actual:
...         for l in difflib.unified_diff([expected], [actual], str(i), str(i)):
...             print l.rstrip("\n")
... 
--- 186
+++ 186
@@ -1 +1 @@
-'\x00S\xd3\xb9\x1a\x7f\x1eT\xef\xfe\xbdmhw\x1e\x8an\x0b,['
+'S\xd3\xb9\x1a\x7f\x1eT\xef\xfe\xbdmhw\x1e\x8an\x0b,['
--- 241
+++ 241
@@ -1 +1 @@
-'\x00\xf6(/Vb\x82\xd7\xb7OJ\xfe\x8e\xf6N\x95\x12\xc5\x9b\x9f'
+'\xf6(/Vb\x82\xd7\xb7OJ\xfe\x8e\xf6N\x95\x12\xc5\x9b\x9f'

[Claude Paroz]

Same patch with test

[Paul McMillan]

In [17418]:

(The changeset message doesn't reference this ticket)

[Aymeric Augustin]

In [17513]:

Added documentation for r17418. Refs #17481.