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) 2000,2003 Ian Jackson
  15  * This file is part of ipif, part of userv-utils
  16  *
  17  * This is free software; you can redistribute it and/or modify it
  18  * under the terms of the GNU General Public License as published by
  19  * the Free Software Foundation; either version 2 of the License, or
  20  * (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful, but
  23  * WITHOUT ANY WARRANTY; without even the implied warranty of
  24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25  * General Public License for more details.
  26  *
  27  * You should have received a copy of the GNU General Public License
  28  * along with userv-utils; if not, write to the Free Software
  29  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  30  */
  31
  32 #include "forwarder.h"
  33 #include "blowfish.h"
  34
  35 struct mechdata {
  36   unsigned char iv[BLOWFISH_BLOCKBYTES];
  37   struct blowfish_cbc_state cbc;
  38 };
  39
  40 static void mds_blowfish(struct mechdata **md_r) {
  41   struct mechdata *md;
  42   unsigned long keysize;
  43   unsigned char key[BLOWFISH_MAXKEYBYTES];
  44
  45   XMALLOC(md);
  46
  47   keysize= getarg_ulong();
  48   arg_assert(!(keysize & 7));
  49   keysize >>= 3;
  50   arg_assert(keysize > 0 && keysize <= BLOWFISH_MAXKEYBYTES);
  51
  52   random_key(md->iv,sizeof(md->iv));
  53   random_key(key,keysize);
  54
  55   blowfish_loadkey(&md->cbc.ek, key,keysize);
  56   *md_r= md;
  57 }
  58
  59 static void mes_blowfish(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  60   mds_blowfish(md_r);
  61 }
  62
  63 static void mds_bfmac(struct mechdata **md_r) {
  64   mds_blowfish(md_r);
  65 }
  66
  67 static void mes_bfmac(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  68   mds_blowfish(md_r);
  69   *maxprefix_io += BLOWFISH_BLOCKBYTES;
  70 }
  71
  72 #define MSGSIZE_OUT                                                   \
  73   msgsize= buf->size;                                                 \
  74   arg_assert(!(msgsize & (BLOWFISH_BLOCKBYTES-1)));
  75
  76 #define MSGSIZE_IN                                                    \
  77   msgsize= buf->size;                                                 \
  78   if (msgsize & (BLOWFISH_BLOCKBYTES-1)) return "not multiple of block size"
  79
  80 #define FOREACH_BLOCK(func,inptr,outptr)                              \
  81  {                                                                    \
  82    unsigned char *ptr;                                                \
  83    blowfish_cbc_setiv(&md->cbc, md->iv);                              \
  84    for (ptr= buf->start;                                              \
  85         ptr < buf->start + msgsize;                                   \
  86         ptr += BLOWFISH_BLOCKBYTES) {                                 \
  87      func(&md->cbc,inptr,outptr);                                     \
  88    }                                                                  \
  89  }
  90
  91 static void menc_blowfish(struct mechdata *md, struct buffer *buf) {
  92   unsigned long msgsize;
  93   MSGSIZE_OUT;
  94   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,ptr);
  95 }
  96
  97 static const char *mdec_blowfish(struct mechdata *md, struct buffer *buf) {
  98   unsigned long msgsize;
  99   MSGSIZE_IN;
 100   FOREACH_BLOCK(blowfish_cbc_decrypt,ptr,ptr);
 101   return 0;
 102 }
 103
 104 static void menc_bfmac(struct mechdata *md, struct buffer *buf) {
 105   unsigned long msgsize;
 106   unsigned char outblock[BLOWFISH_BLOCKBYTES];
 107
 108   MSGSIZE_OUT;
 109   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock);
 110   memcpy(buf_prepend(buf,BLOWFISH_BLOCKBYTES), outblock, BLOWFISH_BLOCKBYTES);
 111 }
 112
 113 static const char *mdec_bfmac(struct mechdata *md, struct buffer *buf) {
 114   unsigned long msgsize;
 115   unsigned char outblock[BLOWFISH_BLOCKBYTES];
 116   unsigned char *checkblock;
 117
 118   BUF_UNPREPEND(checkblock,buf,BLOWFISH_BLOCKBYTES);
 119   MSGSIZE_IN;
 120   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock);
 121   if (memcmp(checkblock,outblock,BLOWFISH_BLOCKBYTES)) return "verify failed";
 122   return 0;
 123 }
 124
 125 const struct mechanism mechlist_blowfish[]= {
 126   STANDARD_MECHANISM("blowfish-cbcmac", bfmac)
 127   STANDARD_MECHANISM("blowfish-cbc",    blowfish)
 128   { 0 }
 129 };