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#include <limits.h>
#include <stdint.h>
#include <string.h>
#include "crypto_hash_sha512.h"
#include "crypto_sign_ed25519.h"
#include "crypto_verify_32.h"
#include "sign_ed25519_ref10.h"
#include "private/common.h"
#include "private/ed25519_ref10.h"
#include "utils.h"
int
_crypto_sign_ed25519_verify_detached(const unsigned char *sig,
const unsigned char *m,
unsigned long long mlen,
const unsigned char *pk,
int prehashed)
{
crypto_hash_sha512_state hs;
unsigned char h[64];
ge25519_p3 check;
ge25519_p3 expected_r;
ge25519_p3 A;
ge25519_p3 sb_ah;
ge25519_p2 sb_ah_p2;
ACQUIRE_FENCE;
#ifdef ED25519_COMPAT
if (sig[63] & 224) {
return -1;
}
#else
if ((sig[63] & 240) != 0 &&
sc25519_is_canonical(sig + 32) == 0) {
return -1;
}
if (ge25519_is_canonical(pk) == 0) {
return -1;
}
#endif
if (ge25519_frombytes_negate_vartime(&A, pk) != 0 ||
ge25519_has_small_order(&A) != 0) {
return -1;
}
if (ge25519_frombytes(&expected_r, sig) != 0 ||
ge25519_has_small_order(&expected_r) != 0) {
return -1;
}
_crypto_sign_ed25519_ref10_hinit(&hs, prehashed);
crypto_hash_sha512_update(&hs, sig, 32);
crypto_hash_sha512_update(&hs, pk, 32);
crypto_hash_sha512_update(&hs, m, mlen);
crypto_hash_sha512_final(&hs, h);
sc25519_reduce(h);
ge25519_double_scalarmult_vartime(&sb_ah_p2, h, &A, sig + 32, NULL);
ge25519_p2_to_p3(&sb_ah, &sb_ah_p2);
ge25519_p3_sub(&check, &expected_r, &sb_ah);
return ge25519_has_small_order(&check) - 1;
}
int
crypto_sign_ed25519_verify_detached(const unsigned char *sig,
const unsigned char *m,
unsigned long long mlen,
const unsigned char *pk)
{
return _crypto_sign_ed25519_verify_detached(sig, m, mlen, pk, 0);
}
int
crypto_sign_ed25519_open(unsigned char *m, unsigned long long *mlen_p,
const unsigned char *sm, unsigned long long smlen,
const unsigned char *pk)
{
unsigned long long mlen;
if (smlen < 64 || smlen - 64 > crypto_sign_ed25519_MESSAGEBYTES_MAX) {
goto badsig;
}
mlen = smlen - 64;
if (crypto_sign_ed25519_verify_detached(sm, sm + 64, mlen, pk) != 0) {
if (m != NULL) {
memset(m, 0, mlen);
}
goto badsig;
}
if (mlen_p != NULL) {
*mlen_p = mlen;
}
if (m != NULL) {
memmove(m, sm + 64, mlen);
}
return 0;
badsig:
if (mlen_p != NULL) {
*mlen_p = 0;
}
return -1;
}
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