Makefile: discuss SHAttered in *_SHA{1,256} discussion
Let's mention the SHAttered attack and more generally why we use the sha1collisiondetection backend by default, and note that for SHA-256 the user should feel free to pick any of the supported backends as far as hashing security is concerned. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Taylor Blau <me@ttaylorr.com>
Ævar Arnfjörð Bjarmason committed
Nov 7, 2022 at 22:23 UTC
d00fa5528b44a8a4e59cb16348f2ddb46f0190ee
1 file changed
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Makefile
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@@ -481,6 +481,17 @@ include shared.mak
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#
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# === SHA-1 backend ===
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#
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+# ==== Security ====
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+#
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+# Due to the SHAttered (https://shattered.io) attack vector on SHA-1
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+# it's strongly recommended to use the sha1collisiondetection
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+# counter-cryptanalysis library for SHA-1 hashing.
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+#
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+# If you know that you can trust the repository contents, or where
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+# potential SHA-1 attacks are otherwise mitigated the other backends
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+# listed in "SHA-1 implementations" are faster than
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+# sha1collisiondetection.
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+#
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# ==== Default SHA-1 backend ====
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#
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# If no *_SHA1 backend is picked, the first supported one listed in
@@ -525,6 +536,11 @@ include shared.mak
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#
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# === SHA-256 backend ===
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#
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+# ==== Security ====
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+#
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+# Unlike SHA-1 the SHA-256 algorithm does not suffer from any known
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+# vulnerabilities, so any implementation will do.
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+#
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# ==== SHA-256 implementations ====
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#
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# Define OPENSSL_SHA256 to use the SHA-256 routines in OpenSSL.