1#include <string.h>
2#include "crypto_sign.h"
3#include "crypto_hash_sha512.h"
4#include "crypto_verify_32.h"
5#include "ge.h"
6#include "sc.h"
7
8int crypto_sign_open(
9 unsigned char *sm, unsigned long long smlen,
10 const unsigned char *pk
11)
12{
13 unsigned char scopy[32];
14 unsigned char h[64];
15 unsigned char rcheck[32];
16 ge_p3 A;
17 ge_p2 R;
18
19 if (smlen < 64) goto badsig;
20 if (sm[63] & 224) goto badsig;
21 if (ge_frombytes_negate_vartime(&A,pk) != 0) goto badsig;
22
23 memmove(scopy,sm + 32,32);
24
25 memmove(sm + 32,pk,32);
26 crypto_hash_sha512(h,sm,smlen);
27 sc_reduce(h);
28
29 ge_double_scalarmult_vartime(&R,h,&A,scopy);
30 ge_tobytes(rcheck,&R);
31 if (crypto_verify_32(rcheck,sm) == 0)
32 return 0;
33
34badsig:
35 return -1;
36}
37