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   1 /* -*-c-*-
   2  *
   3  * $Id: seal.h,v 1.1 2000/06/17 12:08:34 mdw Exp $
   4  *
   5  * The SEAL pseudo-random function family
   6  *
   7  * (c) 2000 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb 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 Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: seal.h,v $
  33  * Revision 1.1  2000/06/17 12:08:34  mdw
  34  * New cipher.
  35  *
  36  */
  37
  38 /*----- Notes on the SEAL pseudo-random function family -------------------*
  39  *
  40  * SEAL is a slightly odd cryptographic primitive.  It was designed by Phil
  41  * Rogaway and Don Coppersmith at IBM, basically as an exercise in producing
  42  * a really fast symmetric cipher of some kind.  They succeeded: SEAL is
  43  * faster than the much simpler RC4.
  44  *
  45  * For each key, it gives you %$2^{32}$% different output streams.  This
  46  * implementation imposes no length limits on the size of output streams and
  47  * performs careful buffer handling to allow arbitrary amounts of data to be
  48  * extracted.  In practice, extracting more than about 64K is possibly dodgy
  49  * from a security point of view.
  50  *
  51  * SEAL is patented.
  52  */
  53
  54 #ifndef CATACOMB_SEAL_H
  55 #define CATACOMB_SEAL_H
  56
  57 #ifdef __cplusplus
  58   extern "C" {
  59 #endif
  60
  61 /*----- Header files ------------------------------------------------------*/
  62
  63 #ifndef CATACOMB_GCIPHER_H
  64 #  include "gcipher.h"
  65 #endif
  66
  67 #ifndef CATACOMB_GRAND_H
  68 #  include "grand.h"
  69 #endif
  70
  71 /*----- Data structures ---------------------------------------------------*/
  72
  73 #define SEAL_R 256
  74
  75 typedef struct seal_key {
  76   octet k[20];                          /* Copy of the 160-bit key */
  77   uint32 t[512];                        /* Substitution table */
  78   uint32 s[256];                        /* Magic for each iteration */
  79   uint32 r[SEAL_R];                     /* Magic for the first 64K */
  80 } seal_key;
  81
  82 typedef struct seal_ctx {
  83   seal_key *k;                          /* Pointer to the key block */
  84   uint32 *r, ri;                        /* Pointer to current magic */
  85   uint32 n, l;                          /* Various indices into things */
  86   uint32 a, b, c, d;                    /* Current chaining variables */
  87   uint32 n1, n2, n3, n4;                /* Increments for the variables */
  88   unsigned i;                           /* Index into current iteration */
  89   octet q[16];                          /* Output buffer */
  90   unsigned qsz;                         /* Number of bytes in the buffer */
  91   uint32 rbuf[SEAL_R];                  /* Buffer for later magic */
  92 } seal_ctx;
  93
  94 /*----- Functions provided ------------------------------------------------*/
  95
  96 /* --- @seal_initkey@ --- *
  97  *
  98  * Arguments:   @seal_key *k@ = pointer to key block
  99  *              @const void *buf@ = pointer to key material
 100  *              @size_t sz@ = size of the key material
 101  *
 102  * Returns:     ---
 103  *
 104  * Use:         Initializes a SEAL key block.  The key material may be any
 105  *              size, but if it's not 20 bytes long it's passed to SHA for
 106  *              hashing first.
 107  */
 108
 109 extern void seal_initkey(seal_key */*k*/,
 110                          const void */*buf*/, size_t /*sz*/);
 111
 112 /* --- @seal_initctx@ --- *
 113  *
 114  * Arguments:   @seal_ctx *c@ = pointer to a SEAL context
 115  *              @seal_key *k@ = pointer to a SEAL key
 116  *              @uint32 n@ = integer sequence number
 117  *
 118  * Returns:     ---
 119  *
 120  * Use:         Initializes a SEAL context which can be used for random
 121  *              number generation or whatever.
 122  */
 123
 124 extern void seal_initctx(seal_ctx */*c*/, seal_key */*k*/, uint32 /*n*/);
 125
 126 /* --- @seal_encrypt@ --- *
 127  *
 128  * Arguments:   @seal_ctx *c@ = pointer to a SEAL context
 129  *              @const void *src@ = pointer to source data
 130  *              @void *dest@ = pointer to destination data
 131  *              @size_t sz@ = size of the data
 132  *
 133  * Returns:     ---
 134  *
 135  * Use:         Encrypts a block of data using SEAL.  If @src@ is zero,
 136  *              @dest@ is filled with SEAL output.  If @dest@ is zero, the
 137  *              SEAL generator is just spun around for a bit.  This shouldn't
 138  *              be necessary, because SEAL isn't RC4.
 139  */
 140
 141 extern void seal_encrypt(seal_ctx */*c*/, const void */*src*/,
 142                          void */*dest*/, size_t /*sz*/);
 143
 144 /*----- Generic cipher interface ------------------------------------------*/
 145
 146 #define SEAL_KEYSZ 20
 147 extern const octet seal_keysz[];
 148
 149 extern const gccipher seal;
 150
 151 /*----- Generic random number generator interface -------------------------*/
 152
 153 /* --- @seal_rand@ --- *
 154  *
 155  * Arguments:   @const void *k@ = pointer to key material
 156  *              @size_t sz@ = size of key material
 157  *              @uint32 n@ = sequence number
 158  *
 159  * Returns:     Pointer to generic random number generator interface.
 160  *
 161  * Use:         Creates a random number interface wrapper around a SEAL
 162  *              pseudorandom function.
 163  */
 164
 165 extern grand *seal_rand(const void */*k*/, size_t /*sz*/, uint32 /*n*/);
 166
 167 /*----- That's all, folks -------------------------------------------------*/
 168
 169 #ifdef __cplusplus
 170   }
 171 #endif
 172
 173 #endif