From: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Date: Tue, 15 Jul 2025 12:03:21 +0000 (+0200)
Subject: gh-72570: mention the incompatibility of XOFs with HMAC (#136676)
X-Git-Tag: v3.15.0a1~970
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a02cf19deed353d1e0e7564468f10aced61c12e8;p=thirdparty%2FPython%2Fcpython.git

gh-72570: mention the incompatibility of XOFs with HMAC (#136676)
---

diff --git a/Doc/library/hmac.rst b/Doc/library/hmac.rst
index d6692033b2d4..57076c38086c 100644
--- a/Doc/library/hmac.rst
+++ b/Doc/library/hmac.rst
@@ -12,6 +12,9 @@
 --------------
 
 This module implements the HMAC algorithm as described by :rfc:`2104`.
+The interface allows to use any hash function with a *fixed* digest size.
+In particular, extendable output functions such as SHAKE-128 or SHAKE-256
+cannot be used with HMAC.
 
 
 .. function:: new(key, msg=None, digestmod)