release/src/router/libsodium/src/libsodium/crypto_stream/salsa208/ref/xor_salsa208.c

   1 /*
   2 version 20140420
   3 D. J. Bernstein
   4 Public domain.
   5 */
   6
   7 #include "crypto_core_salsa208.h"
   8 #include "crypto_stream_salsa208.h"
   9 #include "utils.h"
  10
  11 int crypto_stream_salsa208_xor(
  12         unsigned char *c,
  13   const unsigned char *m,unsigned long long mlen,
  14   const unsigned char *n,
  15   const unsigned char *k
  16 )
  17 {
  18   unsigned char in[16];
  19   unsigned char block[64];
  20   unsigned char kcopy[32];
  21   unsigned int i;
  22   unsigned int u;
  23
  24   if (!mlen) return 0;
  25
  26   for (i = 0;i < 32;++i) kcopy[i] = k[i];
  27   for (i = 0;i < 8;++i) in[i] = n[i];
  28   for (i = 8;i < 16;++i) in[i] = 0;
  29
  30   while (mlen >= 64) {
  31     crypto_core_salsa208(block,in,kcopy,NULL);
  32     for (i = 0;i < 64;++i) c[i] = m[i] ^ block[i];
  33
  34     u = 1;
  35     for (i = 8;i < 16;++i) {
  36       u += (unsigned int) in[i];
  37       in[i] = u;
  38       u >>= 8;
  39     }
  40
  41     mlen -= 64;
  42     c += 64;
  43     m += 64;
  44   }
  45
  46   if (mlen) {
  47     crypto_core_salsa208(block,in,kcopy,NULL);
  48     for (i = 0;i < (unsigned int) mlen;++i) c[i] = m[i] ^ block[i];
  49   }
  50   sodium_memzero(block, sizeof block);
  51   sodium_memzero(kcopy, sizeof kcopy);
  52
  53   return 0;
  54 }