commit 041e9235c1710936a43f73d2f6e87bfc6e1c2242 Author: Nick Mathewson nickm@torproject.org Date: Thu Dec 13 11:26:09 2018 -0500

Lower the loop_max constant in curve25519_basepoint_spot_check()

The point of this function is to make sure that the ed25519-based implementation of curve25519_basepoint() actually works when we start tor, and use the regular fallback implementation if it doesn't. But it accounts for 9% of our startup time in the case when we have directory information, and I think it's safe to make the test shorter. After all, it has yet to find any actual bugs in curved25519_scalarmult_basepoint_donna() on any platforms.

Closes ticket 28838. --- changes/ticket28838 | 8 ++++++++ src/lib/crypt_ops/crypto_curve25519.c | 2 +- 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/changes/ticket28838 b/changes/ticket28838 new file mode 100644 index 000000000..6c290bf82 --- /dev/null +++ b/changes/ticket28838 @@ -0,0 +1,8 @@ + o Minor features (performance): + - Remove about 96% of the work from the function that we run at + startup to test our curve25519_basepoint implementation. Since + this function has yet to find an actual failure, we'll only + run it for 8 iterations instead of 200. Based on our profile + information, this change should save around 8% of our startup + time on typical desktops, and may have a similar effect on + other platforms. Closes ticket 28838. diff --git a/src/lib/crypt_ops/crypto_curve25519.c b/src/lib/crypt_ops/crypto_curve25519.c index e6a39a8c0..f3a9de9fc 100644 --- a/src/lib/crypt_ops/crypto_curve25519.c +++ b/src/lib/crypt_ops/crypto_curve25519.c @@ -289,7 +289,7 @@ curve25519_basepoint_spot_check(void) 0x0d,0xbf,0x3a,0x0d,0x26,0x38,0x1a,0xf4, 0xeb,0xa4,0xa9,0x8e,0xaa,0x9b,0x4e,0x6a }; - const int loop_max=200; + const int loop_max=8; int save_use_ed = curve25519_use_ed; unsigned char e1[32], e2[32]; unsigned char x[32],y[32];