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#include <string.h>
#include "crypto_sign.h"
#include "crypto_hash_sha512.h"
#include "crypto_verify_32.h"
#include "ge.h"
#include "sc.h"
int crypto_sign_open(
unsigned char *sm, unsigned long long smlen,
const unsigned char *pk
)
{
unsigned char scopy[32];
unsigned char h[64];
unsigned char rcheck[32];
ge_p3 A;
ge_p2 R;
if (smlen < 64) goto badsig;
if (sm[63] & 224) goto badsig;
if (ge_frombytes_negate_vartime(&A,pk) != 0) goto badsig;
memmove(scopy,sm + 32,32);
memmove(sm + 32,pk,32);
crypto_hash_sha512(h,sm,smlen);
sc_reduce(h);
ge_double_scalarmult_vartime(&R,h,&A,scopy);
ge_tobytes(rcheck,&R);
if (crypto_verify_32(rcheck,sm) == 0)
return 0;
badsig:
return -1;
}
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