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#include <string.h>
#include "api.h"
#include "crypto_hash_sha512.h"
#include "ge.h"
#include "sc.h"
int
crypto_sign_detached(unsigned char *sig, unsigned long long *siglen,
const unsigned char *m, unsigned long long mlen,
const unsigned char *sk)
{
crypto_hash_sha512_state hs;
unsigned char pk[32];
unsigned char az[64];
unsigned char nonce[64];
unsigned char hram[64];
ge_p3 R;
memmove(pk, sk + 32, 32);
crypto_hash_sha512(az, sk, 32);
az[0] &= 248;
az[31] &= 63;
az[31] |= 64;
crypto_hash_sha512_init(&hs);
crypto_hash_sha512_update(&hs, az + 32, 32);
crypto_hash_sha512_update(&hs, m, mlen);
crypto_hash_sha512_final(&hs, nonce);
memmove(sig + 32, pk, 32);
sc_reduce(nonce);
ge_scalarmult_base(&R, nonce);
ge_p3_tobytes(sig, &R);
crypto_hash_sha512_init(&hs);
crypto_hash_sha512_update(&hs, sig, 64);
crypto_hash_sha512_update(&hs, m, mlen);
crypto_hash_sha512_final(&hs, hram);
sc_reduce(hram);
sc_muladd(sig + 32, hram, az, nonce);
if (siglen != NULL) {
*siglen = 64U;
}
return 0;
}
int
crypto_sign(unsigned char *sm, unsigned long long *smlen,
const unsigned char *m, unsigned long long mlen,
const unsigned char *sk)
{
unsigned long long siglen;
if (crypto_sign_detached(sm, &siglen, m, mlen, sk) != 0 ||
siglen > crypto_sign_ed25519_BYTES) {
*smlen = 0;
memset(sm, 0, mlen + crypto_sign_ed25519_BYTES);
return -1;
}
memmove(sm + siglen, m, mlen);
if (smlen != NULL) {
*smlen = mlen + siglen;
}
return 0;
}
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