git.distorted.org.uk Git - u/mdw/catacomb/blob - symm/seal.h

   1 /* -*-c-*-
   2  *
   3  * The SEAL pseudo-random function family
   4  *
   5  * (c) 2000 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 /*----- Notes on the SEAL pseudo-random function family -------------------*
  29  *
  30  * SEAL is a slightly odd cryptographic primitive.  It was designed by Phil
  31  * Rogaway and Don Coppersmith at IBM, basically as an exercise in producing
  32  * a really fast symmetric cipher of some kind.  They succeeded: SEAL is
  33  * faster than the much simpler RC4.
  34  *
  35  * For each key, it gives you %$2^{32}$% different output streams.  This
  36  * implementation imposes no length limits on the size of output streams and
  37  * performs careful buffer handling to allow arbitrary amounts of data to be
  38  * extracted.  In practice, extracting more than about 64K is possibly dodgy
  39  * from a security point of view.
  40  *
  41  * SEAL is patented.
  42  */
  43
  44 #ifndef CATACOMB_SEAL_H
  45 #define CATACOMB_SEAL_H
  46
  47 #ifdef __cplusplus
  48   extern "C" {
  49 #endif
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #ifndef CATACOMB_GCIPHER_H
  54 #  include "gcipher.h"
  55 #endif
  56
  57 #ifndef CATACOMB_GRAND_H
  58 #  include "grand.h"
  59 #endif
  60
  61 /*----- Data structures ---------------------------------------------------*/
  62
  63 #define SEAL_R 256
  64
  65 typedef struct seal_key {
  66   octet k[20];                          /* Copy of the 160-bit key */
  67   uint32 t[512];                        /* Substitution table */
  68   uint32 s[256];                        /* Magic for each iteration */
  69   uint32 r[SEAL_R];                     /* Magic for the first 64K */
  70 } seal_key;
  71
  72 typedef struct seal_ctx {
  73   seal_key *k;                          /* Pointer to the key block */
  74   uint32 *r, ri;                        /* Pointer to current magic */
  75   uint32 n, l;                          /* Various indices into things */
  76   uint32 a, b, c, d;                    /* Current chaining variables */
  77   uint32 n1, n2, n3, n4;                /* Increments for the variables */
  78   unsigned i;                           /* Index into current iteration */
  79   octet q[16];                          /* Output buffer */
  80   unsigned qsz;                         /* Number of bytes in the buffer */
  81   uint32 rbuf[SEAL_R];                  /* Buffer for later magic */
  82 } seal_ctx;
  83
  84 /*----- Functions provided ------------------------------------------------*/
  85
  86 /* --- @seal_initkey@ --- *
  87  *
  88  * Arguments:   @seal_key *k@ = pointer to key block
  89  *              @const void *buf@ = pointer to key material
  90  *              @size_t sz@ = size of the key material
  91  *
  92  * Returns:     ---
  93  *
  94  * Use:         Initializes a SEAL key block.  The key material may be any
  95  *              size, but if it's not 20 bytes long it's passed to SHA for
  96  *              hashing first.
  97  */
  98
  99 extern void seal_initkey(seal_key */*k*/,
 100                          const void */*buf*/, size_t /*sz*/);
 101
 102 /* --- @seal_initctx@ --- *
 103  *
 104  * Arguments:   @seal_ctx *c@ = pointer to a SEAL context
 105  *              @seal_key *k@ = pointer to a SEAL key
 106  *              @uint32 n@ = integer sequence number
 107  *
 108  * Returns:     ---
 109  *
 110  * Use:         Initializes a SEAL context which can be used for random
 111  *              number generation or whatever.
 112  */
 113
 114 extern void seal_initctx(seal_ctx */*c*/, seal_key */*k*/, uint32 /*n*/);
 115
 116 /* --- @seal_encrypt@ --- *
 117  *
 118  * Arguments:   @seal_ctx *c@ = pointer to a SEAL context
 119  *              @const void *src@ = pointer to source data
 120  *              @void *dest@ = pointer to destination data
 121  *              @size_t sz@ = size of the data
 122  *
 123  * Returns:     ---
 124  *
 125  * Use:         Encrypts a block of data using SEAL.  If @src@ is zero,
 126  *              @dest@ is filled with SEAL output.  If @dest@ is zero, the
 127  *              SEAL generator is just spun around for a bit.  This shouldn't
 128  *              be necessary, because SEAL isn't RC4.
 129  */
 130
 131 extern void seal_encrypt(seal_ctx */*c*/, const void */*src*/,
 132                          void */*dest*/, size_t /*sz*/);
 133
 134 /*----- Generic cipher interface ------------------------------------------*/
 135
 136 #define SEAL_KEYSZ 20
 137 extern const octet seal_keysz[];
 138
 139 extern const gccipher seal;
 140
 141 /*----- Generic random number generator interface -------------------------*/
 142
 143 /* --- @seal_rand@ --- *
 144  *
 145  * Arguments:   @const void *k@ = pointer to key material
 146  *              @size_t sz@ = size of key material
 147  *              @uint32 n@ = sequence number
 148  *
 149  * Returns:     Pointer to generic random number generator interface.
 150  *
 151  * Use:         Creates a random number interface wrapper around a SEAL
 152  *              pseudorandom function.
 153  */
 154
 155 extern grand *seal_rand(const void */*k*/, size_t /*sz*/, uint32 /*n*/);
 156
 157 /*----- That's all, folks -------------------------------------------------*/
 158
 159 #ifdef __cplusplus
 160   }
 161 #endif
 162
 163 #endif