Hashlib/blake2* missing 'data' keyword argument

[JuusoLehtivarjo]

BPO	33729
Nosy	@gpshead, @vstinner, @tiran, @ned-deily, @serhiy-storchaka, @tirkarthi
PRs	bpo-33729: Fix issues with arguments parsing in hashlib. #8346 [3.7] bpo-33729: Fix issues with arguments parsing in hashlib. (GH-8346) #8581 [3.6] bpo-33729: Fix issues with arguments parsing in hashlib. (GH-8346) (GH-8581) #9657

^{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/serhiy-storchaka'
closed_at = None
created_at = <Date 2018-06-01.08:36:11.487>
labels = ['3.8', 'type-bug', '3.7', 'docs']
title = "Hashlib/blake2* missing 'data' keyword argument"
updated_at = <Date 2018-10-13.21:58:53.976>
user = 'https://bugs.python.org/JuusoLehtivarjo'

bugs.python.org fields:

activity = <Date 2018-10-13.21:58:53.976>
actor = 'ned.deily'
assignee = 'serhiy.storchaka'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2018-06-01.08:36:11.487>
creator = 'Juuso Lehtivarjo'
dependencies = []
files = []
hgrepos = []
issue_num = 33729
keywords = ['patch']
message_count = 22.0
messages = ['318370', '321414', '321455', '321945', '321948', '321949', '321955', '322732', '322738', '322740', '322741', '322744', '322781', '322798', '327212', '327256', '327287', '327303', '327304', '327305', '327516', '327675']
nosy_count = 8.0
nosy_names = ['gregory.p.smith', 'vstinner', 'christian.heimes', 'ned.deily', 'docs@python', 'serhiy.storchaka', 'Juuso Lehtivarjo', 'xtreak']
pr_nums = ['8346', '8581', '9657']
priority = None
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue33729'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']

[JuusoLehtivarjo]

In python 3.6.5: hashlib blake2b/blake2s constructors do not recognize 'data' keyword. Try the following:

from hashlib import blake2b
print (blake2b(b"foobar").hexdigest()) # works
print (blake2b(data=b"foobar").hexdigest()) # TypeError: 'data' is an invalid keyword argument for this function

[tiran]

None of the hashlib functions are taking keyword arguments for data:

>>> hashlib.sha256(data=b'foo')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: openssl_sha256() takes no keyword arguments
>>> hashlib.blake2b(data=b'foo')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'data' is an invalid keyword argument for this function

[vstinner]

None of the hashlib functions are taking keyword arguments for data: ...

So it's just a documentation issue, no?

https://docs.python.org/dev/library/hashlib.html#creating-hash-objects

Juuso Lehtivarjo: do you want to write a pull request to fix the documentation?

[tirkarthi]

This was introduced as part of https://hg.python.org/cpython/rev/4969f6d343b1 . In addition to the signature there is also a line at https://docs.python.org/dev/library/hashlib.html#simple-hashing which could be removed

As a shortcut, you can pass the first chunk of data to update directly to the constructor as the first argument (or as data keyword argument)

Thanks

[serhiy-storchaka]

hashlib.blake2b() and some other constructors accept the first chunk of data as the "string" keyword argument.

>>> hashlib.blake2b(string=b'')
<_blake2.blake2b object at 0x7f2847a9c430>
>>> hashlib.blake2s(string=b'')
<_blake2.blake2s object at 0x7f28468f6290>
>>> hashlib.sha3_224(string=b'')
<_sha3.sha3_224 object at 0x7f28468f6608>
>>> hashlib.sha3_256(string=b'')
<_sha3.sha3_256 object at 0x7f28468f6290>
>>> hashlib.sha3_384(string=b'')
<_sha3.sha3_384 object at 0x7f28468f6608>
>>> hashlib.sha3_512(string=b'')
<_sha3.sha3_512 object at 0x7f28468f6290>
>>> hashlib.shake_128(string=b'')
<_sha3.shake_128 object at 0x7f28468f6608>
>>> hashlib.shake_256(string=b'')
<_sha3.shake_256 object at 0x7f28468f6290>

[tiran]

Please treat the first argument as positional-only argument. I don't want to standardize on 'string'.