78 lines
1.3 KiB
C
78 lines
1.3 KiB
C
#include "ed25519.h"
|
|
#include "sha512.h"
|
|
#include "ge.h"
|
|
#include "sc.h"
|
|
|
|
static int consttime_equal(const unsigned char *x, const unsigned char *y) {
|
|
unsigned char r = 0;
|
|
|
|
r = x[0] ^ y[0];
|
|
#define F(i) r |= x[i] ^ y[i]
|
|
F(1);
|
|
F(2);
|
|
F(3);
|
|
F(4);
|
|
F(5);
|
|
F(6);
|
|
F(7);
|
|
F(8);
|
|
F(9);
|
|
F(10);
|
|
F(11);
|
|
F(12);
|
|
F(13);
|
|
F(14);
|
|
F(15);
|
|
F(16);
|
|
F(17);
|
|
F(18);
|
|
F(19);
|
|
F(20);
|
|
F(21);
|
|
F(22);
|
|
F(23);
|
|
F(24);
|
|
F(25);
|
|
F(26);
|
|
F(27);
|
|
F(28);
|
|
F(29);
|
|
F(30);
|
|
F(31);
|
|
#undef F
|
|
|
|
return !r;
|
|
}
|
|
|
|
int ed25519_verify(const unsigned char *signature, const unsigned char *message, size_t message_len, const unsigned char *public_key) {
|
|
unsigned char h[64];
|
|
unsigned char checker[32];
|
|
sha512_context hash;
|
|
ge_p3 A;
|
|
ge_p2 R;
|
|
|
|
if (signature[63] & 224) {
|
|
return 0;
|
|
}
|
|
|
|
if (ge_frombytes_negate_vartime(&A, public_key) != 0) {
|
|
return 0;
|
|
}
|
|
|
|
sha512_init(&hash);
|
|
sha512_update(&hash, signature, 32);
|
|
sha512_update(&hash, public_key, 32);
|
|
sha512_update(&hash, message, message_len);
|
|
sha512_final(&hash, h);
|
|
|
|
sc_reduce(h);
|
|
ge_double_scalarmult_vartime(&R, h, &A, signature + 32);
|
|
ge_tobytes(checker, &R);
|
|
|
|
if (!consttime_equal(checker, signature)) {
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|