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
+16
Makefile
+16
index 7d0fa7adb6..91596bac4c 100644
--- a/Makefile
+++ b/Makefile
@@ -481,6 +481,17 @@ include shared.mak
#
# === SHA-1 backend ===
#
+# ==== Security ====
+#
+# Due to the SHAttered (https://shattered.io) attack vector on SHA-1
+# it's strongly recommended to use the sha1collisiondetection
+# counter-cryptanalysis library for SHA-1 hashing.
+#
+# If you know that you can trust the repository contents, or where
+# potential SHA-1 attacks are otherwise mitigated the other backends
+# listed in "SHA-1 implementations" are faster than
+# sha1collisiondetection.
+#
# ==== Default SHA-1 backend ====
#
# If no *_SHA1 backend is picked, the first supported one listed in
@@ -525,6 +536,11 @@ include shared.mak
#
# === SHA-256 backend ===
#
+# ==== Security ====
+#
+# Unlike SHA-1 the SHA-256 algorithm does not suffer from any known
+# vulnerabilities, so any implementation will do.
+#
# ==== SHA-256 implementations ====
#
# Define OPENSSL_SHA256 to use the SHA-256 routines in OpenSSL.