threema-ios/NaClCrypto/nacl/crypto_secretbox/xsalsa20poly1305/ref/box.c

#include "crypto_onetimeauth_poly1305.h"
#include "crypto_stream_xsalsa20.h"
#include "crypto_secretbox.h"

int crypto_secretbox(
  unsigned char *c,
  const unsigned char *m,unsigned long long mlen,
  const unsigned char *n,
  const unsigned char *k
)
{
  int i;
  if (mlen < 32) return -1;
  crypto_stream_xsalsa20_xor(c,m,mlen,n,k);
  crypto_onetimeauth_poly1305(c + 16,c + 32,mlen - 32,c);
  for (i = 0;i < 16;++i) c[i] = 0;
  return 0;
}

int crypto_secretbox_open(
  unsigned char *m,
  const unsigned char *c,unsigned long long clen,
  const unsigned char *n,
  const unsigned char *k
)
{
  int i;
  unsigned char subkey[32];
  if (clen < 32) return -1;
  crypto_stream_xsalsa20(subkey,32,n,k);
  if (crypto_onetimeauth_poly1305_verify(c + 16,c + 32,clen - 32,subkey) != 0) return -1;
  crypto_stream_xsalsa20_xor(m,c,clen,n,k);
  for (i = 0;i < 32;++i) m[i] = 0;
  return 0;
}