[Python-checkins] bpo-42982: Improve the text on suggested number of iterations of PBKDF2 (GH-24276)
gpshead
webhook-mailer at python.org
Thu Jan 27 03:39:23 EST 2022
https://github.com/python/cpython/commit/897ce9018775bcd679fb49aa17258f8f6e818e23
commit: 897ce9018775bcd679fb49aa17258f8f6e818e23
branch: main
author: Illia Volochii <illia.volochii at gmail.com>
committer: gpshead <greg at krypto.org>
date: 2022-01-27T00:39:09-08:00
summary:
bpo-42982: Improve the text on suggested number of iterations of PBKDF2 (GH-24276)
Less specific number wording (as there is no one right number - the old 100k is too big for some applications and woefully small for others). We now link to NIST SP 800-132 to tell people what to read in there on how to decide for their application.
Co-authored-by: Gregory P. Smith <greg at krypto.org> [Google]
files:
M Doc/library/hashlib.rst
diff --git a/Doc/library/hashlib.rst b/Doc/library/hashlib.rst
index 53320d9cb0d6c..269e8a834d58d 100644
--- a/Doc/library/hashlib.rst
+++ b/Doc/library/hashlib.rst
@@ -249,8 +249,9 @@ include a `salt <https://en.wikipedia.org/wiki/Salt_%28cryptography%29>`_.
a proper source, e.g. :func:`os.urandom`.
The number of *iterations* should be chosen based on the hash algorithm and
- computing power. As of 2013, at least 100,000 iterations of SHA-256 are
- suggested.
+ computing power. As of 2022, hundreds of thousands of iterations of SHA-256
+ are suggested. For rationale as to why and how to choose what is best for
+ your application, read *Appendix A.2.2* of NIST-SP-800-132_.
*dklen* is the length of the derived key. If *dklen* is ``None`` then the
digest size of the hash algorithm *hash_name* is used, e.g. 64 for SHA-512.
@@ -731,6 +732,7 @@ Domain Dedication 1.0 Universal:
.. _SHA-3: https://en.wikipedia.org/wiki/NIST_hash_function_competition
.. _ChaCha: https://cr.yp.to/chacha.html
.. _pyblake2: https://pythonhosted.org/pyblake2/
+.. _NIST-SP-800-132: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf
@@ -754,3 +756,6 @@ Domain Dedication 1.0 Universal:
https://www.ietf.org/rfc/rfc8018.txt
PKCS #5: Password-Based Cryptography Specification Version 2.1
+
+ https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf
+ NIST Recommendation for Password-Based Key Derivation.
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