crypto/wvdiffiehellman.cc

   1 /*
   2  * Worldvisions Weaver Software:
   3  * Copyright (C) 2003 Net Integration Technologies, Inc.
   4  *
   5  * Diffie-Hellman shared secret handshake.
   6  */
   7
   8 #include "wvautoconf.h"
   9 #ifdef __GNUC__
  10 # define alloca __builtin_alloca
  11 #else
  12 # ifdef _MSC_VER
  13 #  include <malloc.h>
  14 #  define alloca _alloca
  15 # else
  16 #  if HAVE_ALLOCA_H
  17 #   include <alloca.h>
  18 #  else
  19 #   ifdef _AIX
  20 #pragma alloca
  21 #   else
  22 #    ifndef alloca /* predefined by HP cc +Olibcalls */
  23 char *alloca ();
  24 #    endif
  25 #   endif
  26 #  endif
  27 # endif
  28 #endif
  29
  30 #include <openssl/bn.h>
  31 #include <stdlib.h>
  32
  33 #include "wvdiffiehellman.h"
  34 #include "strutils.h"
  35
  36 WvDiffieHellman::WvDiffieHellman(const unsigned char *_key, int _keylen,
  37                                  BN_ULONG _generator) :
  38     generator(_generator), log("Diffie-Hellman", WvLog::Debug)
  39 {
  40     int problems;
  41     int check;
  42     {
  43         info = DH_new();
  44         info->p = BN_bin2bn(_key, _keylen, NULL);
  45 //      info->p->top = 0;
  46 //      info->p->dmax = _keylen * 8 / BN_BITS2;
  47 //      info->p->neg = 0;
  48 //      info->p->flags = 0;
  49
  50         info->g = BN_new();
  51         BN_set_word(info->g, generator);
  52 //      info->g->d = &generator;
  53 //      info->g->top = 0;
  54 //      info->g->dmax = 1;
  55 //      info->g->neg = 0;
  56 //      info->g->flags = 0;
  57     }
  58
  59     check = BN_mod_word(info->p, 24);
  60     DH_check(info, &problems);
  61     if (problems & DH_CHECK_P_NOT_PRIME)
  62         log(WvLog::Error, "Using a composite number for authentication.\n");
  63     if (problems & DH_CHECK_P_NOT_SAFE_PRIME)
  64         log(WvLog::Error,"Using an unsafe prime number for authentication.\n");
  65     if (problems & DH_NOT_SUITABLE_GENERATOR)
  66         log(WvLog::Error, "Can you just use 2 instead of %s (%s)!!\n",
  67             BN_bn2hex(info->g), check);
  68     if (problems & DH_UNABLE_TO_CHECK_GENERATOR)
  69         log(WvLog::Notice, "Using a strange argument for diffie-hellman.\n");
  70     DH_generate_key(info);
  71 }
  72
  73 int WvDiffieHellman::pub_key_len()
  74 {
  75     return BN_num_bytes(info->pub_key);
  76 }
  77
  78 int WvDiffieHellman::get_public_value(WvBuf &outbuf, int len)
  79 {
  80     int key_len = BN_num_bytes(info->pub_key);
  81     if (key_len < len)
  82         len = key_len;
  83
  84     // alloca is stack allocated, don't free it.
  85     unsigned char *foo = (unsigned char*)alloca(key_len);
  86     BN_bn2bin(info->pub_key, foo);
  87     outbuf.put(foo, len);
  88
  89     return len;
  90 }
  91
  92 bool WvDiffieHellman::create_secret(WvBuf &inbuf, size_t in_len, WvBuf& outbuf)
  93 {
  94     unsigned char *foo = (unsigned char *)alloca(DH_size(info));
  95    log("My public value\n%s\nYour public value\n%s\n",BN_bn2hex(info->pub_key),
  96        hexdump_buffer(inbuf.peek(0, in_len), in_len, false));
  97     int len = DH_compute_key (foo, BN_bin2bn(inbuf.get(in_len), in_len, NULL),
  98                               info);
  99
 100     outbuf.put(foo, len);
 101
 102     log("Shared secret\n%s\n",hexdump_buffer(outbuf.peek(0, len), len, false));
 103
 104     return true;
 105 }