id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
19980	Signer broken when SECRET_KEY contains non-ASCII bytes	Vincent Driessen	MattBlack	"This happens on Django 1.5 only.

When the `SECRET_KEY` setting contains non-ASCII bytes (which is very likely for randomly generated keys), the following code breaks

{{{#!python
from django.conf import settings
from django.core.signing import Signer
 
settings.SECRET_KEY = b'\xe7'  # binary key with non-ASCII chars
 
s = Signer()
print(s.sign('foo'))
}}}

Relevant stack trace:

{{{#!text
Traceback (most recent call last):
  File ""minimal_example.py"", line 7, in <module>
    s.sign('foo')
  File ""/Users/nvie/.virtualenvs/foo/lib/python2.7/site-packages/django/core/signing.py"", line 175, in sign
    return str('%s%s%s') % (value, self.sep, self.signature(value))
  File ""/Users/nvie/.virtualenvs/foo/lib/python2.7/site-packages/django/core/signing.py"", line 169, in signature
    signature = base64_hmac(self.salt + 'signer', value, self.key)
  File ""/Users/nvie/.virtualenvs/foo/lib/python2.7/site-packages/django/core/signing.py"", line 75, in base64_hmac
    return b64_encode(salted_hmac(salt, value, key).digest())
  File ""/Users/nvie/.virtualenvs/foo/lib/python2.7/site-packages/django/utils/crypto.py"", line 48, in salted_hmac
    key = hashlib.sha1((key_salt + secret).encode('utf-8')).digest()
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe7 in position 0: ordinal not in range(128)
}}}

This is due to the fact that unicode and bytes are concatenated and, as a result, the bytes are implicitly decoded, which is an invalid operation, hence the UnicodeDecodeError. The error, thus, is perfectly valid.

I think the source of the bug is that, internally, the `Signer` works with text-based keys, salts and values, where it should work with byte streams instead."	Bug	closed	Core (Other)	1.5	Normal	fixed	signer		Accepted	1	0	0	0	0	0