hmac unnecessarily restricts input to "bytes"

[jborgstrom]

BPO	18240
Nosy	@gpshead, @tiran
Files	hmac.patch: Proposed patch hmac2.patch: Updated patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/tiran'
closed_at = <Date 2013-07-01.11:09:50.812>
created_at = <Date 2013-06-17.10:38:28.690>
labels = ['type-feature', 'library']
title = 'hmac unnecessarily restricts input to "bytes"'
updated_at = <Date 2013-11-12.08:43:07.457>
user = 'https://bugs.python.org/jborgstrom'

bugs.python.org fields:

activity = <Date 2013-11-12.08:43:07.457>
actor = 'mpb'
assignee = 'christian.heimes'
closed = True
closed_date = <Date 2013-07-01.11:09:50.812>
closer = 'christian.heimes'
components = ['Library (Lib)']
creation = <Date 2013-06-17.10:38:28.690>
creator = 'jborgstrom'
dependencies = []
files = ['30628', '30637']
hgrepos = []
issue_num = 18240
keywords = ['patch']
message_count = 10.0
messages = ['191321', '191324', '191374', '191395', '191396', '191398', '191399', '191757', '192120', '192121']
nosy_count = 5.0
nosy_names = ['gregory.p.smith', 'christian.heimes', 'python-dev', 'jborgstrom', 'mpb']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue18240'
versions = ['Python 3.4']

[jborgstrom]

Problem:
In hmac.py there's a type check that verifies that the msg parameter is of type bytes().

if not isinstance(msg, bytes):
    raise TypeError("expected bytes, but got %r" % type(msg).__name__)

That is incorrect. The hmac module should also work with other data types as long as they are supported by the underlying hashlib module, for example bytearray() and memoryview().

Suggestion:
Remove that type check. hashlib will make sure str() and other invalid data types raises a TypeError.

[tiran]

Good idea!

We can also lift the restriction for key a bit. It can also take a bytearray as argument. bytearray has translate() and supports bytes + bytearay.

[tiran]

Thanks for your patch! Please add tests for the new feature. The documentation needs versionchanged tags, too.

[jborgstrom]

Patch updated to include tests and versionchanged tags

[tiran]

Thanks for your update.

As far as I can tell you haven't signed our contributor agreement yet. Can you please do so?

http://www.python.org/psf/contrib/
http://www.python.org/psf/contrib/contrib-form/

[jborgstrom]

Of course. I've now signed and filed the agreement.

[tiran]

It may take a day or two until your signature makes it through red tape. I'll get back to you. :)

[tiran]

Your account hasn't been flagged yet. I'm going to ping the person in charge.

[python-dev]

New changeset 636947fe131e by Christian Heimes in branch 'default':
bpo-18240: The HMAC module is no longer restricted to bytes and accepts
http://hg.python.org/cpython/rev/636947fe131e

[tiran]

Your CLA came through and I have applied your patch. Thank you very much for your contribution!