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

   1 #include "api.h"
   2 #include "crypto_hash_sha512.h"
   3 #include "crypto_verify_32.h"
   4 #include "ge.h"
   5 #include "sc.h"
   6
   7 int crypto_sign_open(
   8   unsigned char *m,unsigned long long *mlen,
   9   const unsigned char *sm,unsigned long long smlen,
  10   const unsigned char *pk
  11 )
  12 {
  13   unsigned char h[64];
  14   unsigned char checkr[32];
  15   ge_p3 A;
  16   ge_p2 R;
  17   unsigned long long i;
  18
  19   *mlen = -1;
  20   if (smlen < 64) return -1;
  21   if (sm[63] & 224) return -1;
  22   if (ge_frombytes_negate_vartime(&A,pk) != 0) return -1;
  23
  24   for (i = 0;i < smlen;++i) m[i] = sm[i];
  25   for (i = 0;i < 32;++i) m[32 + i] = pk[i];
  26   crypto_hash_sha512(h,m,smlen);
  27   sc_reduce(h);
  28
  29   ge_double_scalarmult_vartime(&R,h,&A,sm + 32);
  30   ge_tobytes(checkr,&R);
  31   if (crypto_verify_32(checkr,sm) != 0) {
  32     for (i = 0;i < smlen;++i) m[i] = 0;
  33     return -1;
  34   }
  35
  36   for (i = 0;i < smlen - 64;++i) m[i] = sm[64 + i];
  37   for (i = smlen - 64;i < smlen;++i) m[i] = 0;
  38   *mlen = smlen - 64;
  39   return 0;
  40 }