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  * This file is part of ipif, part of userv-utils
  15  *
  16  * Copyright 1996-2013 Ian Jackson <ijackson@chiark.greenend.org.uk>
  17  * Copyright 1998 David Damerell <damerell@chiark.greenend.org.uk>
  18  * Copyright 1999,2003
  19  *    Chancellor Masters and Scholars of the University of Cambridge
  20  * Copyright 2010 Tony Finch <fanf@dotat.at>
  21  *
  22  * This is free software; you can redistribute it and/or modify it
  23  * under the terms of the GNU General Public License as published by
  24  * the Free Software Foundation; either version 3 of the License, or
  25  * (at your option) any later version.
  26  *
  27  * This program is distributed in the hope that it will be useful, but
  28  * WITHOUT ANY WARRANTY; without even the implied warranty of
  29  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  30  * General Public License for more details.
  31  *
  32  * You should have received a copy of the GNU General Public License
  33  * along with userv-utils; if not, see http://www.gnu.org/licenses/.
  34  */
  35
  36 #include "forwarder.h"
  37 #include "blowfish.h"
  38
  39 struct mechdata {
  40   unsigned char iv[BLOWFISH_BLOCKBYTES];
  41   struct blowfish_cbc_state cbc;
  42 };
  43
  44 static void mds_blowfish(struct mechdata **md_r) {
  45   struct mechdata *md;
  46   unsigned long keysize;
  47   unsigned char key[BLOWFISH_MAXKEYBYTES];
  48
  49   XMALLOC(md);
  50
  51   keysize= getarg_ulong();
  52   arg_assert(!(keysize & 7));
  53   keysize >>= 3;
  54   arg_assert(keysize > 0 && keysize <= BLOWFISH_MAXKEYBYTES);
  55
  56   random_key(md->iv,sizeof(md->iv));
  57   random_key(key,keysize);
  58
  59   blowfish_loadkey(&md->cbc.ek, key,keysize);
  60   *md_r= md;
  61 }
  62
  63 static void mes_blowfish(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  64   mds_blowfish(md_r);
  65 }
  66
  67 static void mds_bfmac(struct mechdata **md_r) {
  68   mds_blowfish(md_r);
  69 }
  70
  71 static void mes_bfmac(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) {
  72   mds_blowfish(md_r);
  73   *maxprefix_io += BLOWFISH_BLOCKBYTES;
  74 }
  75
  76 #define MSGSIZE_OUT                                                   \
  77   msgsize= buf->size;                                                 \
  78   arg_assert(!(msgsize & (BLOWFISH_BLOCKBYTES-1)));
  79
  80 #define MSGSIZE_IN                                                    \
  81   msgsize= buf->size;                                                 \
  82   if (msgsize & (BLOWFISH_BLOCKBYTES-1)) return "not multiple of block size"
  83
  84 #define FOREACH_BLOCK(func,inptr,outptr)                              \
  85  {                                                                    \
  86    unsigned char *ptr;                                                \
  87    blowfish_cbc_setiv(&md->cbc, md->iv);                              \
  88    for (ptr= buf->start;                                              \
  89         ptr < buf->start + msgsize;                                   \
  90         ptr += BLOWFISH_BLOCKBYTES) {                                 \
  91      func(&md->cbc,inptr,outptr);                                     \
  92    }                                                                  \
  93  }
  94
  95 static void menc_blowfish(struct mechdata *md, struct buffer *buf) {
  96   unsigned long msgsize;
  97   MSGSIZE_OUT;
  98   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,ptr);
  99 }
 100
 101 static const char *mdec_blowfish(struct mechdata *md, struct buffer *buf) {
 102   unsigned long msgsize;
 103   MSGSIZE_IN;
 104   FOREACH_BLOCK(blowfish_cbc_decrypt,ptr,ptr);
 105   return 0;
 106 }
 107
 108 static void menc_bfmac(struct mechdata *md, struct buffer *buf) {
 109   unsigned long msgsize;
 110   unsigned char outblock[BLOWFISH_BLOCKBYTES];
 111
 112   MSGSIZE_OUT;
 113   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock);
 114   memcpy(buf_prepend(buf,BLOWFISH_BLOCKBYTES), outblock, BLOWFISH_BLOCKBYTES);
 115 }
 116
 117 static const char *mdec_bfmac(struct mechdata *md, struct buffer *buf) {
 118   unsigned long msgsize;
 119   unsigned char outblock[BLOWFISH_BLOCKBYTES];
 120   unsigned char *checkblock;
 121
 122   BUF_UNPREPEND(checkblock,buf,BLOWFISH_BLOCKBYTES);
 123   MSGSIZE_IN;
 124   FOREACH_BLOCK(blowfish_cbc_encrypt,ptr,outblock);
 125   if (memcmp(checkblock,outblock,BLOWFISH_BLOCKBYTES)) return "verify failed";
 126   return 0;
 127 }
 128
 129 const struct mechanism mechlist_blowfish[]= {
 130   STANDARD_MECHANISM("blowfish-cbcmac", bfmac)
 131   STANDARD_MECHANISM("blowfish-cbc",    blowfish)
 132   { 0 }
 133 };