Nick Coghlan <ncogh...@gmail.com> added the comment:

To repeat, the specific feature being proposed for retention is:

* a function called hmac.total_compare() that is clearly documented as being 
still vulnerable to timing analysis given a sufficiently sophisticated 
attacker, while still being more resistant to such analysis than the standard 
comparison operator

* restricting that function to operating on bytes, to eliminate timing 
variations associated with encoding/decoding of Unicode text and reduce those 
associated with the calculation of integer values

Leaking less information on each comparison is intended to increase the 
effectiveness of higher level timing attack countermeasures (such as rate 
limiting and lockouts). Anyone that would use "hmac.total_compare" and call it 
done is likely using ordinary comparison today (which is even worse).

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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue15061>
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