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author | Micah Anderson <micah@riseup.net> | 2014-08-11 13:49:21 -0400 |
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committer | Micah Anderson <micah@riseup.net> | 2014-08-11 13:49:21 -0400 |
commit | 2e59f9740a29439df7c7a56cf0ae83dec3081d31 (patch) | |
tree | d5e7c4e74c9a0f1ea999327d2e68b1dd27be00e0 /src/libsodium/crypto_sign/ed25519/ref10/fe_isnegative.c |
initial import of debian version from mentors0.6.1
Diffstat (limited to 'src/libsodium/crypto_sign/ed25519/ref10/fe_isnegative.c')
-rw-r--r-- | src/libsodium/crypto_sign/ed25519/ref10/fe_isnegative.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/libsodium/crypto_sign/ed25519/ref10/fe_isnegative.c b/src/libsodium/crypto_sign/ed25519/ref10/fe_isnegative.c new file mode 100644 index 0000000..3b2c8b8 --- /dev/null +++ b/src/libsodium/crypto_sign/ed25519/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; +} |