int crypto_sign_ed25519(
unsigned char *sm,unsigned long long *smlen,
const unsigned char *m,unsigned long long mlen,
const unsigned char *sk
)
{
sc25519 sck, scs, scsk;
ge25519 ger;
unsigned char r[32];
unsigned char s[32];
unsigned char extsk[64];
unsigned long long i;
unsigned char hmg[crypto_hash_sha512_BYTES];
unsigned char hram[crypto_hash_sha512_BYTES];
crypto_hash_sha512(extsk, sk, 32);
extsk[0] &= 248;
extsk[31] &= 127;
extsk[31] |= 64;
*smlen = mlen+64;
for(i=0;i<mlen;i++)
sm[64 + i] = m[i];
for(i=0;i<32;i++)
sm[32 + i] = extsk[32+i];
crypto_hash_sha512(hmg, sm+32, mlen+32); /* Generate k as h(extsk[32],...,extsk[63],m) */
/* Computation of R */
sc25519_from64bytes(&sck, hmg);
ge25519_scalarmult_base(&ger, &sck);
ge25519_pack(r, &ger);
/* Computation of s */
for(i=0;i<32;i++)
sm[i] = r[i];
get_hram(hram, sm, sk+32, sm, mlen+64);
sc25519_from64bytes(&scs, hram);
sc25519_from32bytes(&scsk, extsk);
sc25519_mul(&scs, &scs, &scsk);
sc25519_add(&scs, &scs, &sck);
sc25519_to32bytes(s,&scs); /* cat s */
for(i=0;i<32;i++)
sm[32 + i] = s[i];
return 0;
}
// Step 3
// y = (sk_r + c * sk) mod #(B) with sk secret
int schnorr_id_response(uint8_t response[SCHNORR_ID_RESPONSEBYTES],
const uint8_t sk[SCHNORR_SECRETKEYBYTES],
const uint8_t sk_r[SCHNORR_SECRETKEYBYTES],
const uint8_t challenge[SCHNORR_ID_CHALLENGEBYTES]) {
sc25519 sc_sk;
sc25519 sc_sk_r;
sc25519 sc_challenge;
sc25519_from32bytes(&sc_sk, sk);
sc25519_from32bytes(&sc_sk_r, sk_r);
sc25519_from_challenge_bytes(&sc_challenge, challenge);
sc25519_mul(&sc_sk, &sc_sk, &sc_challenge);
sc25519_add(&sc_sk, &sc_sk, &sc_sk_r);
sc25519_to32bytes(response, &sc_sk);
return 0;
}
int crypto_sign_open_batch(
unsigned char* const m[],unsigned long long mlen[],
unsigned char* const sm[],const unsigned long long smlen[],
unsigned char* const pk[],
unsigned long long num
)
{
int ret = 0;
unsigned long long i, j;
shortsc25519 r[MAXBATCH];
sc25519 scalars[2*MAXBATCH+1];
ge25519 points[2*MAXBATCH+1];
unsigned char hram[crypto_hash_sha512_BYTES];
unsigned long long batchsize;
for (i = 0;i < num;++i) mlen[i] = -1;
while (num >= 3) {
batchsize = num;
if (batchsize > MAXBATCH) batchsize = MAXBATCH;
for (i = 0;i < batchsize;++i)
if (smlen[i] < 64) goto fallback;
randombytes((unsigned char*)r,sizeof(shortsc25519) * batchsize);
/* Computing scalars[0] = ((r1s1 + r2s2 + ...)) */
for(i=0;i<batchsize;i++)
{
sc25519_from32bytes(&scalars[i], sm[i]+32);
sc25519_mul_shortsc(&scalars[i], &scalars[i], &r[i]);
}
for(i=1;i<batchsize;i++)
sc25519_add(&scalars[0], &scalars[0], &scalars[i]);
/* Computing scalars[1] ... scalars[batchsize] as r[i]*H(R[i],A[i],m[i]) */
for(i=0;i<batchsize;i++)
{
get_hram(hram, sm[i], pk[i], m[i], smlen[i]);
sc25519_from64bytes(&scalars[i+1],hram);
sc25519_mul_shortsc(&scalars[i+1],&scalars[i+1],&r[i]);
}
/* Setting scalars[batchsize+1] ... scalars[2*batchsize] to r[i] */
for(i=0;i<batchsize;i++)
sc25519_from_shortsc(&scalars[batchsize+i+1],&r[i]);
/* Computing points */
points[0] = ge25519_base;
for(i=0;i<batchsize;i++)
if (ge25519_unpackneg_vartime(&points[i+1], pk[i])) goto fallback;
for(i=0;i<batchsize;i++)
if (ge25519_unpackneg_vartime(&points[batchsize+i+1], sm[i])) goto fallback;
ge25519_multi_scalarmult_vartime(points, points, scalars, 2*batchsize+1);
if (ge25519_isneutral_vartime(points)) {
for(i=0;i<batchsize;i++)
{
for(j=0;j<smlen[i]-64;j++)
m[i][j] = sm[i][j + 64];
mlen[i] = smlen[i]-64;
}
} else {
fallback:
for (i = 0;i < batchsize;++i)
ret |= crypto_sign_open(m[i], &mlen[i], sm[i], smlen[i], pk[i]);
}
m += batchsize;
mlen += batchsize;
sm += batchsize;
smlen += batchsize;
pk += batchsize;
num -= batchsize;
}
for (i = 0;i < num;++i)
ret |= crypto_sign_open(m[i], &mlen[i], sm[i], smlen[i], pk[i]);
return ret;
}
