The usedforsecurity keyword only argument added to the hash constructors is useful for FIPS builds and similar restrictive environment with non-technical requirements that legacy algorithms be forbidden by their implementations without being explicitly annotated as not being used for any security related purposes. Linux distros with FIPS support benefit from this being standard rather than making up their own way(s) to do it.
Contributed and Signed-off-by: Christian Heimes christian@python.org
* help(hashlib) didn't work because of incorrect module name in blake2b and
blake2s classes.
* Constructors blake2*(), sha3_*(), shake_*() and keccak_*() incorrectly
accepted keyword argument "string" for binary data, but documented as
accepting the "data" keyword argument. Now this parameter is positional-only.
* Keyword-only parameters in blake2b() and blake2s() were not documented as
keyword-only.
* Default value for some parameters of blake2b() and blake2s() was None,
which is not acceptable value.
* The length argument for shake_*.digest() was wrapped out to 32 bits.
* The argument for shake_128.digest() and shake_128.hexdigest() was not
positional-only as intended.
* TypeError messages for incorrect arguments in all constructors sha3_*(),
shake_*() and keccak_*() incorrectly referred to sha3_224.
Also made the following enhancements:
* More accurately specified input and result types for strings, bytes and
bytes-like objects.
* Unified positional parameter names for update() and constructors.
* Improved formatting.
All Blake2 params have to be encoded in little-endian byte order. For
the two multi-byte integer params, leaf_length and node_offset, that
means that assigning a native-endian integer to them appears to work on
little-endian platforms, but gives the wrong result on big-endian. The
current libb2 API doesn't make that very clear, and @sneves is working
on new API functions in the GH issue above. In the meantime, we can work
around the problem by explicitly assigning little-endian values to the
parameter block.
See https://github.com/BLAKE2/libb2/issues/12.
Rework the code choosing BLAKE2 code paths from using the optimized
variant on all x86_64 machines to using it when SSSE3 or better
supported instructions sets are available.
Firstly, this solves the problem of using pure SSE2 code path on x86_64
machines. As reported in the bug, this code is slower than the reference
code on all tested x86_64 machines. Furthermore, on Athlon64 that lacks
SSSE3, it is even 2.5 times slower than the reference code! Checking
for SSSE3 therefore ensures that the optimized implementation will only
be used when it has a chance of performing better.
Secondly, this makes it possible to use SSSE3+ optimizations on 32-bit
x86 systems. This allows for even 2 times speed gain on modern 32-bit
x86 systems (tested in a 32-bit chroot).
Victor Stinner
Christian Heimes
Jeroen Demeyer
Peter Eisentraut
Serhiy Storchaka
Jack O'Connor
Michał Górny
Antoine Pitrou
Benjamin Peterson