release/src/router/dnscrypt/src/libnacl/crypto_stream/salsa20/ref/stream.c

   1 /*
   2 version 20080913
   3 D. J. Bernstein
   4 Public domain.
   5 */
   6
   7 #include "crypto_core_salsa20.h"
   8 #include "crypto_stream.h"
   9
  10 typedef unsigned int uint32;
  11
  12 static const unsigned char sigma[16] = "expand 32-byte k";
  13
  14 int crypto_stream(
  15         unsigned char *c,unsigned long long clen,
  16   const unsigned char *n,
  17   const unsigned char *k
  18 )
  19 {
  20   unsigned char in[16];
  21   unsigned char block[64];
  22   int i;
  23   unsigned int u;
  24
  25   if (!clen) return 0;
  26
  27   for (i = 0;i < 8;++i) in[i] = n[i];
  28   for (i = 8;i < 16;++i) in[i] = 0;
  29
  30   while (clen >= 64) {
  31     crypto_core_salsa20(c,in,k,sigma);
  32
  33     u = 1;
  34     for (i = 8;i < 16;++i) {
  35       u += (unsigned int) in[i];
  36       in[i] = u;
  37       u >>= 8;
  38     }
  39
  40     clen -= 64;
  41     c += 64;
  42   }
  43
  44   if (clen) {
  45     crypto_core_salsa20(block,in,k,sigma);
  46     for (i = 0;i < clen;++i) c[i] = block[i];
  47   }
  48   return 0;
  49 }