release/src/router/libsodium/src/libsodium/crypto_stream/salsa2012/ref/xor_salsa2012.c

   1 /*
   2 version 20080913
   3 D. J. Bernstein
   4 Public domain.
   5 */
   6
   7 #include "api.h"
   8 #include "crypto_core_salsa2012.h"
   9
  10 typedef unsigned int uint32;
  11
  12 static const unsigned char sigma[16] = {
  13     'e', 'x', 'p', 'a', 'n', 'd', ' ', '3', '2', '-', 'b', 'y', 't', 'e', ' ', 'k'
  14 };
  15
  16 int crypto_stream_xor(
  17         unsigned char *c,
  18   const unsigned char *m,unsigned long long mlen,
  19   const unsigned char *n,
  20   const unsigned char *k
  21 )
  22 {
  23   unsigned char in[16];
  24   unsigned char block[64];
  25   unsigned long long i;
  26   unsigned int u;
  27
  28   if (!mlen) return 0;
  29
  30   for (i = 0;i < 8;++i) in[i] = n[i];
  31   for (i = 8;i < 16;++i) in[i] = 0;
  32
  33   while (mlen >= 64) {
  34     crypto_core_salsa2012(block,in,k,sigma);
  35     for (i = 0;i < 64;++i) c[i] = m[i] ^ block[i];
  36
  37     u = 1;
  38     for (i = 8;i < 16;++i) {
  39       u += (unsigned int) in[i];
  40       in[i] = u;
  41       u >>= 8;
  42     }
  43
  44     mlen -= 64;
  45     c += 64;
  46     m += 64;
  47   }
  48
  49   if (mlen) {
  50     crypto_core_salsa2012(block,in,k,sigma);
  51     for (i = 0;i < mlen;++i) c[i] = m[i] ^ block[i];
  52   }
  53   return 0;
  54 }