toxcore/nacl/crypto_box/wrapper-open.cpp
2013-07-02 09:53:34 -04:00

28 lines
1.1 KiB
C++

#include <string>
using std::string;
#include "crypto_box.h"
string crypto_box_open(const string &c,const string &n,const string &pk,const string &sk)
{
if (pk.size() != crypto_box_PUBLICKEYBYTES) throw "incorrect public-key length";
if (sk.size() != crypto_box_SECRETKEYBYTES) throw "incorrect secret-key length";
if (n.size() != crypto_box_NONCEBYTES) throw "incorrect nonce length";
size_t clen = c.size() + crypto_box_BOXZEROBYTES;
unsigned char cpad[clen];
for (int i = 0;i < crypto_box_BOXZEROBYTES;++i) cpad[i] = 0;
for (int i = crypto_box_BOXZEROBYTES;i < clen;++i) cpad[i] = c[i - crypto_box_BOXZEROBYTES];
unsigned char mpad[clen];
if (crypto_box_open(mpad,cpad,clen,
(const unsigned char *) n.c_str(),
(const unsigned char *) pk.c_str(),
(const unsigned char *) sk.c_str()
) != 0)
throw "ciphertext fails verification";
if (clen < crypto_box_ZEROBYTES)
throw "ciphertext too short"; // should have been caught by _open
return string(
(char *) mpad + crypto_box_ZEROBYTES,
clen - crypto_box_ZEROBYTES
);
}