git.distorted.org.uk Git - u/mdw/putty/blob - sshsha.c

   1 /*
   2  * SHA core transform algorithm, used here solely as a `stirring'
   3  * function for the PuTTY random number pool. Implemented directly
   4  * from the specification by Simon Tatham.
   5  */
   6
   7 #include "ssh.h"
   8
   9 #define rol(x,y) ( ((x) << (y)) | (((word32)x) >> (32-y)) )
  10
  11 void SHATransform(word32 *digest, word32 *block) {
  12     word32 w[80];
  13     word32 a,b,c,d,e;
  14     int t;
  15
  16     for (t = 0; t < 16; t++)
  17         w[t] = block[t];
  18
  19     for (t = 16; t < 80; t++) {
  20         word32 tmp = w[t-3] ^ w[t-8] ^ w[t-14] ^ w[t-16];
  21         w[t] = rol(tmp, 1);
  22     }
  23
  24     a = digest[0];
  25     b = digest[1];
  26     c = digest[2];
  27     d = digest[3];
  28     e = digest[4];
  29
  30     for (t = 0; t < 20; t++) {
  31         word32 tmp = rol(a, 5) + ( (b&c) | (d&~b) ) + e + w[t] + 0x5a827999;
  32         e = d; d = c; c = rol(b, 30); b = a; a = tmp;
  33     }
  34     for (t = 20; t < 40; t++) {
  35         word32 tmp = rol(a, 5) + (b^c^d) + e + w[t] + 0x6ed9eba1;
  36         e = d; d = c; c = rol(b, 30); b = a; a = tmp;
  37     }
  38     for (t = 40; t < 60; t++) {
  39         word32 tmp = rol(a, 5) + ( (b&c) | (b&d) | (c&d) ) + e + w[t] + 0x8f1bbcdc;
  40         e = d; d = c; c = rol(b, 30); b = a; a = tmp;
  41     }
  42     for (t = 60; t < 80; t++) {
  43         word32 tmp = rol(a, 5) + (b^c^d) + e + w[t] + 0xca62c1d6;
  44         e = d; d = c; c = rol(b, 30); b = a; a = tmp;
  45     }
  46
  47     digest[0] += a;
  48     digest[1] += b;
  49     digest[2] += c;
  50     digest[3] += d;
  51     digest[4] += e;
  52 }