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Clinic signatures of HACL* hash functions are inconsistent with OpenSSL implementation #134696

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Clinic signatures of HACL* hash functions are inconsistent with OpenSSL implementation#134696
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picnixz
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3.13only security fixes3.14bugs and security fixes3.15bugs and security fixesextension-modulesC modules in the Modules dirtype-bugAn unexpected behavior, bug, or error

Description

@8R0WNI3
8R0WNI3
opened on May 26, 2025

Bug description:

According to its docstring, the function hashlib.shake_128(...).hexdigest() should accept an argument length, either as positional or as keyword argument. However, since Python 3.14, the function only accepts positional arguments and fails with TypeError: shake_128.hexdigest() takes no keyword arguments otherwise.

I narrowed the root cause for this behaviour down to the following two commits (I'm not 100% sure though as I don't have any C-background):

Reproducer:

import hashlib
hashlib.shake_128(b'').hexdigest(1) # working
hashlib.shake_128(b'').hexdigest(length=1) # not working anymore, but was working before

For example, on Python Python 3.13.3 (main, Apr 8 2025, 13:54:08) [Clang 17.0.0 (clang-1700.0.13.3)] on my mac I can still use the keyword argument, but on alpine:edge Python 3.12.10 (main, May 21 2025, 16:23:36) [GCC 14.2.0] on linux it is expecting positional arguments only.

CPython versions tested on:

CPython main branch, 3.14, 3.13, 3.12

Operating systems tested on:

Linux, macOS

Linked PRs

Activity

  1. 8R0WNI3
    added
    type-bugAn unexpected behavior, bug, or error
    on May 26, 2025
  2. picnixz
    added
    extension-modulesC modules in the Modules dir
    topic-argument-clinic
    on May 26, 2025

  3. picnixz commented on May 26, 2025

    @picnixz
    picnixz
    on May 26, 2025
    Member

    I cannot reproduce the issue. On Python 3.15, it works well and I don't think I change anything between 3.14 and 3.15 (namely I can use a keyword argument). If you cannot use a keyword argument on 3.12, then I think it's ok? I mean, the recent behavior is an extension of the old one.

  4. picnixz
    added
    pendingThe issue will be closed if no feedback is provided
    on May 26, 2025

  5. 8R0WNI3 commented on May 26, 2025

    @8R0WNI3
    8R0WNI3
    on May 26, 2025
    Author

    On alpine:3 running Python 3.12.10 (main, May 21 2025, 20:03:03) [GCC 14.2.0], the keyword argument is allowed (this was the behaviour in the past and seems to be the case in 3.15 as well. However, on alpine:edge running Python 3.12.10 (main, May 21 2025, 16:23:36) [GCC 14.2.0], the keyword argument is not allowed anymore.

  6. picnixz commented on May 26, 2025

    @picnixz
    picnixz
    on May 26, 2025
    Member

    3.12 is security-only so we won't fix this IMO (it's not a security issue). In your comment, you're linking 3.12.10 twice so I don't really understand which one is 3.12 or not (only the timestamps change and I don't know which correspond to what)

  7. encukou commented on May 26, 2025

    @encukou
    encukou
    on May 26, 2025
    Member

    Could you share how you're installing dependencies & building CPython on alpine:edge?

  8. 8R0WNI3 commented on May 26, 2025

    @8R0WNI3
    8R0WNI3
    on May 26, 2025
    Author

    Reproducer:

    > docker run -it alpine:edge
  > apk add python3
  > python3 -c "import hashlib; print(hashlib.shake_128(b'').hexdigest(length=1))"

    However, in the meantime I figured if I run apk upgrade libcrypto3, the keyword argument is accepted again, so this might be an issue between Python and openssl?

  9. picnixz commented on May 26, 2025

    @picnixz
    picnixz
    on May 26, 2025
    Member

    I may have an idea. What's the output of type(hashlib.shak_128(b''). If OpenSSl is not installed, then we may have fell back on the HACL* implementation

  10. picnixz commented on May 26, 2025

    @picnixz
    picnixz
    on May 26, 2025
    Member

    And indeed there is some issue here:

    Image

    This is in _sha3module. So the HACL* implementation doesn't allow for keyword arguments. Thanks for spotting this disparity.

  11. picnixz
    changed the title [-]`hashlib.shake_128().hexdigest()` no support for keyword arguments anymore[/-] [+]Signature for `shake_{128,256}.hexdigest()` is not inconsistent between OpenSSL and HACL* implementation[/+] on May 26, 2025
  12. picnixz
    added
    3.13only security fixes
    and removed
    pendingThe issue will be closed if no feedback is provided
    topic-argument-clinic
    on May 26, 2025

  13. 10 remaining items

  14. picnixz
    changed the title [-]Clinic signatures in `_sha3` and `_blake2` are inconsistent with OpenSSL implementation[/-] [+]Clinic signatures of HACL* hash functions are inconsistent with OpenSSL implementation[/+] on May 26, 2025
  15. picnixz
    added 9 commits that reference this issue on May 31, 2025

    gh-134696: align OpenSSL and HACL*-based hash functions constructors …

    c6e63d9

    [3.14] pythongh-134696: align OpenSSL and HACL*-based hash functions …

    8235738

    [3.13] pythongh-134696: align OpenSSL and HACL*-based hash functions …

    4ba757a

    gh-134696: fix `hashlib` tests for FIPS-only BLAKE-2 buildbot (#134968)

    379d0bc

    pythongh-134696: fix `hashlib` tests for FIPS-only BLAKE-2 buildbot (p…

    622dea0

    [3.14] pythongh-134696: align OpenSSL and HACL*-based hash functions …

    ab91460

    [3.13] pythongh-134696: align OpenSSL and HACL*-based hash functions …

    ad4c913

    [3.14] gh-134696: align OpenSSL and HACL*-based hash functions constr…

    777fd49

    [3.13] gh-134696: align OpenSSL and HACL*-based hash functions constr…

    2c325e2
  16. picnixz
    closed this as completedon Jun 2, 2025
  17. Pranjal095
    added 2 commits that reference this issue on Jul 12, 2025

    pythongh-134696: align OpenSSL and HACL*-based hash functions constru…

    cd0fc32

    pythongh-134696: fix `hashlib` tests for FIPS-only BLAKE-2 buildbot (p…

    bac898b
  18. taegyunkim
    added 2 commits that reference this issue on Aug 4, 2025

    pythongh-134696: align OpenSSL and HACL*-based hash functions constru…

    f7105df

    pythongh-134696: fix `hashlib` tests for FIPS-only BLAKE-2 buildbot (p…

    5e8fec9
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