`hmac.digest()` and `HMAC(...).digest()` disagree when blocksize is smaller than 16
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@picnixz is already working on this.
Since Aug 9, 2026.
stdlib
type-bug
- Dominant language
- Python
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Description
Bug report
Bug description:
hmac.digest() and HMAC(...).digest() return DIFFERENT MACs for any digest whose block_size is below 16, because hmac._compute_digest_fallback reads block_size raw while hmac.HMAC._init_old clamps it to 64.
CPython versions tested on:
CPython main branch
Operating systems tested on:
No response
Linked PRs
- gh-155429
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