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#include <string.h>
#include "crypto_scalarmult_ed25519.h"
#include "private/ed25519_ref10.h"
#include "utils.h"
static int
_crypto_scalarmult_ed25519_is_inf(const unsigned char s[32])
{
unsigned char c;
unsigned int i;
c = s[0] ^ 0x01;
for (i = 1; i < 31; i++) {
c |= s[i];
}
c |= s[31] & 0x7f;
return ((((unsigned int) c) - 1U) >> 8) & 1;
}
static inline void
_crypto_scalarmult_ed25519_clamp(unsigned char k[32])
{
k[0] &= 248;
k[31] &= 127;
k[31] |= 64;
}
int
crypto_scalarmult_ed25519(unsigned char *q, const unsigned char *n,
const unsigned char *p)
{
unsigned char *t = q;
ge25519_p3 Q;
ge25519_p3 P;
unsigned int i;
if (ge25519_is_canonical(p) == 0 || ge25519_has_small_order(p) != 0 ||
ge25519_frombytes(&P, p) != 0 || ge25519_is_on_main_subgroup(&P) == 0) {
return -1;
}
for (i = 0; i < 32; ++i) {
t[i] = n[i];
}
_crypto_scalarmult_ed25519_clamp(t);
ge25519_scalarmult(&Q, t, &P);
ge25519_p3_tobytes(q, &Q);
if (_crypto_scalarmult_ed25519_is_inf(q) != 0 || sodium_is_zero(n, 32)) {
return -1;
}
return 0;
}
int
crypto_scalarmult_ed25519_base(unsigned char *q,
const unsigned char *n)
{
unsigned char *t = q;
ge25519_p3 Q;
unsigned int i;
for (i = 0; i < 32; ++i) {
t[i] = n[i];
}
_crypto_scalarmult_ed25519_clamp(t);
ge25519_scalarmult_base(&Q, t);
ge25519_p3_tobytes(q, &Q);
if (sodium_is_zero(n, 32) != 0) {
return -1;
}
return 0;
}
size_t
crypto_scalarmult_ed25519_bytes(void)
{
return crypto_scalarmult_ed25519_BYTES;
}
size_t
crypto_scalarmult_ed25519_scalarbytes(void)
{
return crypto_scalarmult_ed25519_SCALARBYTES;
}
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