release/src/router/dnscrypt/src/libnacl/crypto_onetimeauth/poly1305/ref/auth.c

   1 /*
   2 20080912
   3 D. J. Bernstein
   4 Public domain.
   5 */
   6
   7 #include "crypto_onetimeauth.h"
   8
   9 static void add(unsigned int h[17],const unsigned int c[17])
  10 {
  11   unsigned int j;
  12   unsigned int u;
  13   u = 0;
  14   for (j = 0;j < 17;++j) { u += h[j] + c[j]; h[j] = u & 255; u >>= 8; }
  15 }
  16
  17 static void squeeze(unsigned int h[17])
  18 {
  19   unsigned int j;
  20   unsigned int u;
  21   u = 0;
  22   for (j = 0;j < 16;++j) { u += h[j]; h[j] = u & 255; u >>= 8; }
  23   u += h[16]; h[16] = u & 3;
  24   u = 5 * (u >> 2);
  25   for (j = 0;j < 16;++j) { u += h[j]; h[j] = u & 255; u >>= 8; }
  26   u += h[16]; h[16] = u;
  27 }
  28
  29 static const unsigned int minusp[17] = {
  30   5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 252
  31 } ;
  32
  33 static void freeze(unsigned int h[17])
  34 {
  35   unsigned int horig[17];
  36   unsigned int j;
  37   unsigned int negative;
  38   for (j = 0;j < 17;++j) horig[j] = h[j];
  39   add(h,minusp);
  40   negative = -(h[16] >> 7);
  41   for (j = 0;j < 17;++j) h[j] ^= negative & (horig[j] ^ h[j]);
  42 }
  43
  44 static void mulmod(unsigned int h[17],const unsigned int r[17])
  45 {
  46   unsigned int hr[17];
  47   unsigned int i;
  48   unsigned int j;
  49   unsigned int u;
  50
  51   for (i = 0;i < 17;++i) {
  52     u = 0;
  53     for (j = 0;j <= i;++j) u += h[j] * r[i - j];
  54     for (j = i + 1;j < 17;++j) u += 320 * h[j] * r[i + 17 - j];
  55     hr[i] = u;
  56   }
  57   for (i = 0;i < 17;++i) h[i] = hr[i];
  58   squeeze(h);
  59 }
  60
  61 int crypto_onetimeauth(unsigned char *out,const unsigned char *in,unsigned long long inlen,const unsigned char *k)
  62 {
  63   unsigned int j;
  64   unsigned int r[17];
  65   unsigned int h[17];
  66   unsigned int c[17];
  67
  68   r[0] = k[0];
  69   r[1] = k[1];
  70   r[2] = k[2];
  71   r[3] = k[3] & 15;
  72   r[4] = k[4] & 252;
  73   r[5] = k[5];
  74   r[6] = k[6];
  75   r[7] = k[7] & 15;
  76   r[8] = k[8] & 252;
  77   r[9] = k[9];
  78   r[10] = k[10];
  79   r[11] = k[11] & 15;
  80   r[12] = k[12] & 252;
  81   r[13] = k[13];
  82   r[14] = k[14];
  83   r[15] = k[15] & 15;
  84   r[16] = 0;
  85
  86   for (j = 0;j < 17;++j) h[j] = 0;
  87
  88   while (inlen > 0) {
  89     for (j = 0;j < 17;++j) c[j] = 0;
  90     for (j = 0;(j < 16) && (j < inlen);++j) c[j] = in[j];
  91     c[j] = 1;
  92     in += j; inlen -= j;
  93     add(h,c);
  94     mulmod(h,r);
  95   }
  96
  97   freeze(h);
  98
  99   for (j = 0;j < 16;++j) c[j] = k[j + 16];
 100   c[16] = 0;
 101   add(h,c);
 102   for (j = 0;j < 16;++j) out[j] = h[j];
 103   return 0;
 104 }