release/src/router/dnscrypt/src/libnacl/crypto_sign/edwards25519sha512batch/ref/sign.c

   1 #include "api.h"
   2 #include "crypto_sign.h"
   3 #include "crypto_hash_sha512.h"
   4 #include "randombytes.h"
   5 #include "crypto_verify_32.h"
   6
   7 #include "ge25519.h"
   8
   9 int crypto_sign_keypair(
  10     unsigned char *pk,
  11     unsigned char *sk
  12     )
  13 {
  14   sc25519 scsk;
  15   ge25519 gepk;
  16
  17   randombytes(sk, 32);
  18   crypto_hash_sha512(sk, sk, 32);
  19   sk[0] &= 248;
  20   sk[31] &= 127;
  21   sk[31] |= 64;
  22
  23   sc25519_from32bytes(&scsk,sk);
  24
  25   ge25519_scalarmult_base(&gepk, &scsk);
  26   ge25519_pack(pk, &gepk);
  27   return 0;
  28 }
  29
  30 int crypto_sign(
  31     unsigned char *sm,unsigned long long *smlen,
  32     const unsigned char *m,unsigned long long mlen,
  33     const unsigned char *sk
  34     )
  35 {
  36   sc25519 sck, scs, scsk;
  37   ge25519 ger;
  38   unsigned char r[32];
  39   unsigned char s[32];
  40   unsigned long long i;
  41   unsigned char hmg[crypto_hash_sha512_BYTES];
  42   unsigned char hmr[crypto_hash_sha512_BYTES];
  43
  44   *smlen = mlen+64;
  45   for(i=0;i<mlen;i++)
  46     sm[32 + i] = m[i];
  47   for(i=0;i<32;i++)
  48     sm[i] = sk[32+i];
  49   crypto_hash_sha512(hmg, sm, mlen+32); /* Generate k as h(m,sk[32],...,sk[63]) */
  50
  51   sc25519_from64bytes(&sck, hmg);
  52   ge25519_scalarmult_base(&ger, &sck);
  53   ge25519_pack(r, &ger);
  54
  55   for(i=0;i<32;i++)
  56     sm[i] = r[i];
  57
  58   crypto_hash_sha512(hmr, sm, mlen+32); /* Compute h(m,r) */
  59   sc25519_from64bytes(&scs, hmr);
  60   sc25519_mul(&scs, &scs, &sck);
  61
  62   sc25519_from32bytes(&scsk, sk);
  63   sc25519_add(&scs, &scs, &scsk);
  64
  65   sc25519_to32bytes(s,&scs); /* cat s */
  66   for(i=0;i<32;i++)
  67     sm[mlen+32+i] = s[i];
  68
  69   return 0;
  70 }
  71
  72 int crypto_sign_open(
  73     unsigned char *m,unsigned long long *mlen,
  74     const unsigned char *sm,unsigned long long smlen,
  75     const unsigned char *pk
  76     )
  77 {
  78   int i;
  79   unsigned char t1[32], t2[32];
  80   ge25519 get1, get2, gepk;
  81   sc25519 schmr, scs;
  82   unsigned char hmr[crypto_hash_sha512_BYTES];
  83
  84   if (ge25519_unpack_vartime(&get1, sm)) return -1;
  85   if (ge25519_unpack_vartime(&gepk, pk)) return -1;
  86
  87   crypto_hash_sha512(hmr,sm,smlen-32);
  88
  89   sc25519_from64bytes(&schmr, hmr);
  90   ge25519_scalarmult(&get1, &get1, &schmr);
  91   ge25519_add(&get1, &get1, &gepk);
  92   ge25519_pack(t1, &get1);
  93
  94   sc25519_from32bytes(&scs, &sm[smlen-32]);
  95   ge25519_scalarmult_base(&get2, &scs);
  96   ge25519_pack(t2, &get2);
  97
  98   for(i=0;i<smlen-64;i++)
  99     m[i] = sm[i + 32];
 100   *mlen = smlen-64;
 101
 102   return crypto_verify_32(t1, t2);
 103 }