release/src/router/libsodium/src/libsodium/crypto_sign/ed25519/ref10/fe_isnonzero.c

   1 #include "fe.h"
   2 #include "crypto_verify_32.h"
   3
   4 /*
   5 return 1 if f == 0
   6 return 0 if f != 0
   7
   8 Preconditions:
   9    |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
  10 */
  11
  12 static unsigned char zero[32];
  13
  14 int fe_isnonzero(const fe f)
  15 {
  16   unsigned char s[32];
  17   fe_tobytes(s,f);
  18   return crypto_verify_32(s,zero);
  19 }