mdw@git.distorted.org.uk Git - become/blob - src/crypt.h

   1 /* -*-c-*-
   2  *
   3  * $Id: crypt.h,v 1.4 1998/01/12 16:45:57 mdw Exp $
   4  *
   5  * Cryptographic transfer of `become' requests
   6  *
   7  * (c) 1998 EBI
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of `become'
  13  *
  14  * `Become' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `Become' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `become'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: crypt.h,v $
  32  * Revision 1.4  1998/01/12 16:45:57  mdw
  33  * Fix copyright date.
  34  *
  35  * Revision 1.3  1997/09/26 09:14:58  mdw
  36  * Merged blowfish branch into trunk.
  37  *
  38  * Revision 1.2.2.1  1997/09/26 09:08:04  mdw
  39  * Use the Blowfish encryption algorithm instead of IDEA.  This is partly
  40  * because I prefer Blowfish (without any particularly strong evidence) but
  41  * mainly because IDEA is patented and Blowfish isn't.
  42  *
  43  * Revision 1.2  1997/08/04 10:24:21  mdw
  44  * Sources placed under CVS control.
  45  *
  46  * Revision 1.1  1997/07/21  13:47:51  mdw
  47  * Initial revision
  48  *
  49  */
  50
  51 #ifndef CRYPT_H
  52 #define CRYPT_H
  53
  54 #ifdef __cplusplus
  55   extern "C" {
  56 #endif
  57
  58 /*----- Required headers --------------------------------------------------*/
  59
  60 #include <string.h>
  61
  62 #ifndef BECOME_H
  63 #  include "become.h"
  64 #endif
  65
  66 #ifndef CONFIG_H
  67 #  include "config.h"
  68 #endif
  69
  70 /*----- Type definitions and data structures ------------------------------*/
  71
  72 /* --- Encryption formats --- */
  73
  74 enum {
  75   cryptType_blowfish,                   /* Symmetric Blowfish encryption */
  76   cryptType_rsa                         /* Public key RSA (later project) */
  77 };
  78
  79 /* --- Blowfish has a variable key size --- *
  80  *
  81  * Fix a key size here.
  82  */
  83
  84 #define BLOWFISH_KEYSIZE (16u)
  85
  86 /* --- Encrypted buffer format --- *
  87  *
  88  * C structures are no good here.  Time for some explicit offsets.
  89  */
  90
  91 enum {
  92   crq_cryptType = 0,                    /* Encryption type (1 byte) */
  93   crq_iv = crq_cryptType + 1,           /* Plaintext IV (8 bytes) */
  94   crq_session = crq_iv + 8,             /* Session key (16 bytes) */
  95   crq_cipher = crq_session + 16,        /* Where to start encrypting */
  96   crq_time = crq_cipher,                /* Time stamp (4 bytes) */
  97   crq_pid = crq_time + 4,               /* Process ID (4 bytes) */
  98   crq_from = crq_pid + 4,               /* From user id (4 bytes) */
  99   crq_to = crq_from + 4,                /* To user id (4 bytes) */
 100   crq_cmd = crq_to + 4,                 /* Command string (lots of bytes) */
 101   crq_check = crq_cmd + CMDLEN_MAX,     /* Checksum for request (4 bytes) */
 102   crq_size = crq_check + 4              /* Size of encrypted request */
 103 };
 104
 105 /* --- Encrypted result format --- */
 106
 107 enum {
 108   crp_iv = 0,                           /* Plaintext IV (8 bytes) */
 109   crp_cipher = crp_iv + 8,              /* Where to start encrypting */
 110   crp_time = crp_cipher,                /* Time of request (4 bytes) */
 111   crp_pid = crp_time + 4,               /* Process ID of client (4 bytes) */
 112   crp_answer = crp_pid + 4,             /* Answer (1 or 0) (1 byte) */
 113   crp_check = crp_answer + 1,           /* Checksum for reply (4 bytes) */
 114   crp_size = crp_check + 4              /* Size of encrypted reply */
 115 };
 116
 117 /*----- Functions provided ------------------------------------------------*/
 118
 119 /* --- @crypt_packRequest@ --- *
 120  *
 121  * Arguments:   @request *rq@ = pointer to request block
 122  *              @unsigned char *buff@ = pointer to a buffer
 123  *              @time_t t@ = the current time
 124  *              @pid_t pid@ = my process ID
 125  *              @unsigned char *k@ = pointer to 128-bit key
 126  *              @unsigned char *sk@ = where to put the session key
 127  *
 128  * Returns:     The number of bytes written.
 129  *
 130  * Use:         Packs a request block into a buffer.  The buffer should have
 131  *              space for at least @crq_size@ bytes.  The buffer comes back
 132  *              encrypted and ready to send.
 133  */
 134
 135 extern void crypt_packRequest(request */*rq*/, unsigned char */*buff*/,
 136                               time_t /*t*/, pid_t /*pid*/,
 137                               unsigned char */*k*/, unsigned char */*sk*/);
 138
 139 /* --- @crypt_unpackRequest@ --- *
 140  *
 141  * Arguments:   @reqest *rq@ = pointer to destination request block
 142  *              @unsigned char *buff@ = pointer to source buffer
 143  *              @unsigned char *k@ = pointer to encryption key
 144  *              @unsigned char *sk@ = pointer to where to store session key
 145  *              @unsigned char *rpl@ = where to start building reply
 146  *
 147  * Returns:     ---
 148  *
 149  * Use:         Decrypts and unpacks a request buffer.
 150  */
 151
 152 extern int crypt_unpackRequest(request */*rq*/, unsigned char */*buff*/,
 153                                unsigned char */*k*/, unsigned char */*sk*/,
 154                                unsigned char */*rpl*/);
 155
 156 /* --- @crypt_packReply@ --- *
 157  *
 158  * Arguments:   @unsigned char *buff@ = pointer to reply block
 159  *              @unsigned char *sk@ = pointer to session key
 160  *              @int answer@ = yes or no
 161  *
 162  * Returns:     ---
 163  *
 164  * Use:         Packs and encrypts a reply block.
 165  */
 166
 167 extern void crypt_packReply(unsigned char */*buff*/, unsigned char */*sk*/,
 168                             int /*answer*/);
 169
 170 /* --- @crypt_unpackReply@ --- *
 171  *
 172  * Arguments:   @unsigned char *buff@ = pointer to reply buffer
 173  *              @unsigned char *sk@ = pointer to session key
 174  *              @time_t t@ = time at which request was sent
 175  *              @pid_t pid@ = my process ID
 176  *
 177  * Returns:     >0 if request granted, zero if denied, <0 if reply rejected
 178  *
 179  * Use:         Unpacks a reply block, and informs the caller of the outcome.
 180  */
 181
 182 extern int crypt_unpackReply(unsigned char */*buff*/, unsigned char */*sk*/,
 183                              time_t /*t*/, pid_t /*pid*/);
 184
 185 /*----- That's all, folks -------------------------------------------------*/
 186
 187 #ifdef __cplusplus
 188   }
 189 #endif
 190
 191 #endif