release/src/router/libsodium/src/libsodium/crypto_stream/salsa20/ref/xor_salsa20_ref.c

   1 /*
   2 version 20080913
   3 D. J. Bernstein
   4 Public domain.
   5 */
   6
   7 #include "api.h"
   8 #include "crypto_core_salsa20.h"
   9
  10 #ifndef HAVE_AMD64_ASM
  11
  12 typedef unsigned int uint32;
  13
  14 static const unsigned char sigma[16] = {
  15     'e', 'x', 'p', 'a', 'n', 'd', ' ', '3', '2', '-', 'b', 'y', 't', 'e', ' ', 'k'
  16 };
  17
  18 int crypto_stream_xor(
  19         unsigned char *c,
  20   const unsigned char *m,unsigned long long mlen,
  21   const unsigned char *n,
  22   const unsigned char *k
  23 )
  24 {
  25   unsigned char in[16];
  26   unsigned char block[64];
  27   unsigned long long i;
  28   unsigned int u;
  29
  30   if (!mlen) return 0;
  31
  32   for (i = 0;i < 8;++i) in[i] = n[i];
  33   for (i = 8;i < 16;++i) in[i] = 0;
  34
  35   while (mlen >= 64) {
  36     crypto_core_salsa20(block,in,k,sigma);
  37     for (i = 0;i < 64;++i) c[i] = m[i] ^ block[i];
  38
  39     u = 1;
  40     for (i = 8;i < 16;++i) {
  41       u += (unsigned int) in[i];
  42       in[i] = u;
  43       u >>= 8;
  44     }
  45
  46     mlen -= 64;
  47     c += 64;
  48     m += 64;
  49   }
  50
  51   if (mlen) {
  52     crypto_core_salsa20(block,in,k,sigma);
  53     for (i = 0;i < mlen;++i) c[i] = m[i] ^ block[i];
  54   }
  55   return 0;
  56 }
  57
  58 #endif