git/sha256 at 9ea1378d046d764642718f1b070689072bde4601 - git

Tree: 9ea1378d04

brian m. carlson e555735836 sha256: add support for Nettle For SHA-256, we currently have support for OpenSSL and libgcrypt because these two libraries contain optimized implementations that can take advantage of native processor instructions. However, OpenSSL is not suitable for linking against for Linux distros due to licensing incompatibilities with the GPLv2, and libgcrypt has been less favored by cryptographers due to some security-related implementation issues, which, while not affecting our use of hash algorithms, has affected its reputation. Let's add another option that's compatible with the GPLv2, which is Nettle. This is an option which is generally better than libgcrypt because on many distros GnuTLS (which uses Nettle) is used for HTTPS and therefore as a practical matter it will be available on most systems. As a result, prefer it over libgcrypt and our built-in implementation. Nettle also has recently gained support for Intel's SHA-NI instructions, which compare very favorably to other implementations, as well as assembly implementations for when SHA-NI is not available. A git gc on git.git sees a 12% performance improvement with Nettle over our block SHA-256 implementation due to general assembly improvements. With SHA-NI, the performance of raw SHA-256 on a 2 GiB file goes from 7.296 seconds with block SHA-256 to 1.523 seconds with Nettle. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>		3 years ago
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block	…
gcrypt.h	…
nettle.h	sha256: add support for Nettle	3 years ago