mdw@git.distorted.org.uk Git - userv-utils/blob - ipif/mech-blowfish.c

   1 /*
   2  * Blowfish mechanism for udp tunnel
   3  *
   4  * mechanisms: blowfish-cbc, blowfish-cbcmac
   5  * arguments: key size in bits (must be multiple of 8)
   6  *
   7  * key values: 8 byte random IV and n byte random key
   8  *
   9  * restrictions: plaintext length must be multiple of block size (8 bytes)
  10  * encoding:         do CBC encryption overwriting message
  11  * encoding for MAC: do CBC and prepend last ciphertext block
  12  */
  13 /*
  14  * Copyright (C) 2000 Ian Jackson
  15  *
  16  * This is free software; you can redistribute it and/or modify it
  17  * under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful, but
  22  * WITHOUT ANY WARRANTY; without even the implied warranty of
  23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  24  * General Public License for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License
  27  * along with userv-utils; if not, write to the Free Software
  28  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  29  */
  30
  31 #include "forwarder.h"
  32 #include "blowfish.h"
  33
  34 struct mechdata {
  35   unsigned char iv[BLOWFISH_BLOCKBYTES];
  36   struct blowfish_cbc_state cbc;
  37 };
  38
  39 static void mds_blowfish(struct mechdata **md_r) {
  40   struct mechdata *md;
  41   unsigned long keysize;
  42   unsigned char key[BLOWFISH_MAXKEYBYTES];
  43
  44   XMALLOC(md);
  45
  46   keysize= getarg_ulong();
  47   arg_assert(!(keysize & 7));
  48   keysize >>= 3;
  49   arg_assert(keysize > 0 && keysize <= BLOWFISH_MAXKEYBYTES);
  50
  51   random_key(md->iv,sizeof(md->iv));
  52   random_key(key,keysize);
  53
  54   blowfish_loadkey(&md->cbc.ek, key,keysize);
  55   *md_r= md;
  56 }
  57
  58 static void mes_blowfish(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  59   mds_blowfish(md_r);
  60 }
  61
  62 static void mds_bfmac(struct mechdata **md_r) {
  63   mds_blowfish(md_r);
  64 }
  65
  66 static void mes_bfmac(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  67   mds_blowfish(md_r);
  68   *maxprefix_io += BLOWFISH_BLOCKBYTES;
  69 }
  70
  71 #define MSGSIZE_OUT                                                   \
  72   msgsize= buf->size;                                                 \
  73   arg_assert(!(msgsize & (BLOWFISH_BLOCKBYTES-1)));
  74
  75 #define MSGSIZE_IN                                                    \
  76   msgsize= buf->size;                                                 \
  77   if (msgsize & (BLOWFISH_BLOCKBYTES-1)) return "not multiple of block size"
  78
  79 #define FOREACH_BLOCK(func,inptr,outptr)                              \
  80  {                                                                    \
  81    unsigned char *ptr;                                                \
  82    blowfish_cbc_setiv(&md->cbc, md->iv);                              \
  83    for (ptr= buf->start;                                              \
  84         ptr < buf->start + msgsize;                                   \
  85         ptr += BLOWFISH_BLOCKBYTES) {                                 \
  86      func(&md->cbc,inptr,outptr);                                     \
  87    }                                                                  \
  88  }
  89
  90 static void menc_blowfish(struct mechdata *md, struct buffer *buf) {
  91   unsigned long msgsize;
  92   MSGSIZE_OUT;
  93   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,ptr);
  94 }
  95
  96 static const char *mdec_blowfish(struct mechdata *md, struct buffer *buf) {
  97   unsigned long msgsize;
  98   MSGSIZE_IN;
  99   FOREACH_BLOCK(blowfish_cbc_decrypt,ptr,ptr);
 100   return 0;
 101 }
 102
 103 static void menc_bfmac(struct mechdata *md, struct buffer *buf) {
 104   unsigned long msgsize;
 105   unsigned char outblock[BLOWFISH_BLOCKBYTES];
 106
 107   MSGSIZE_OUT;
 108   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock);
 109   memcpy(buf_prepend(buf,BLOWFISH_BLOCKBYTES), outblock, BLOWFISH_BLOCKBYTES);
 110 }
 111
 112 static const char *mdec_bfmac(struct mechdata *md, struct buffer *buf) {
 113   unsigned long msgsize;
 114   unsigned char outblock[BLOWFISH_BLOCKBYTES];
 115   unsigned char *checkblock;
 116
 117   BUF_UNPREPEND(checkblock,buf,BLOWFISH_BLOCKBYTES);
 118   MSGSIZE_IN;
 119   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock);
 120   if (memcmp(checkblock,outblock,BLOWFISH_BLOCKBYTES)) return "verify failed";
 121   return 0;
 122 }
 123
 124 const struct mechanism mechlist_blowfish[]= {
 125   STANDARD_MECHANISM("blowfish-cbcmac", bfmac)
 126   STANDARD_MECHANISM("blowfish-cbc",    blowfish)
 127   { 0 }
 128 };