release/src/router/dnscrypt/src/libnacl/crypto_box/wrapper-open.cpp

   1 #include <string>
   2 using std::string;
   3 #include "crypto_box.h"
   4
   5 string crypto_box_open(const string &c,const string &n,const string &pk,const string &sk)
   6 {
   7   if (pk.size() != crypto_box_PUBLICKEYBYTES) throw "incorrect public-key length";
   8   if (sk.size() != crypto_box_SECRETKEYBYTES) throw "incorrect secret-key length";
   9   if (n.size() != crypto_box_NONCEBYTES) throw "incorrect nonce length";
  10   size_t clen = c.size() + crypto_box_BOXZEROBYTES;
  11   unsigned char cpad[clen];
  12   for (int i = 0;i < crypto_box_BOXZEROBYTES;++i) cpad[i] = 0;
  13   for (int i = crypto_box_BOXZEROBYTES;i < clen;++i) cpad[i] = c[i - crypto_box_BOXZEROBYTES];
  14   unsigned char mpad[clen];
  15   if (crypto_box_open(mpad,cpad,clen,
  16                        (const unsigned char *) n.c_str(),
  17                        (const unsigned char *) pk.c_str(),
  18                        (const unsigned char *) sk.c_str()
  19                      ) != 0)
  20     throw "ciphertext fails verification";
  21   if (clen < crypto_box_ZEROBYTES)
  22     throw "ciphertext too short"; // should have been caught by _open
  23   return string(
  24     (char *) mpad + crypto_box_ZEROBYTES,
  25     clen - crypto_box_ZEROBYTES
  26   );
  27 }