From 0a4bc84b2f681dfd89b501648f65a951d876e2d8 Mon Sep 17 00:00:00 2001 From: ShenNoether Date: Sun, 23 Aug 2015 14:48:50 -0600 Subject: Added ref10 shen_ed25519_ref code, which includes code that can replace crypto-ops with a version straight from Bernstein's ref 10 --- src/crypto/shen_ed25519_ref/ref10/fe_isnegative.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 src/crypto/shen_ed25519_ref/ref10/fe_isnegative.c (limited to 'src/crypto/shen_ed25519_ref/ref10/fe_isnegative.c') diff --git a/src/crypto/shen_ed25519_ref/ref10/fe_isnegative.c b/src/crypto/shen_ed25519_ref/ref10/fe_isnegative.c new file mode 100644 index 000000000..3b2c8b8d5 --- /dev/null +++ b/src/crypto/shen_ed25519_ref/ref10/fe_isnegative.c @@ -0,0 +1,16 @@ +#include "fe.h" + +/* +return 1 if f is in {1,3,5,...,q-2} +return 0 if f is in {0,2,4,...,q-1} + +Preconditions: + |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc. +*/ + +int fe_isnegative(const fe f) +{ + unsigned char s[32]; + fe_tobytes(s,f); + return s[0] & 1; +} -- cgit v1.2.3