release/src/router/nettle/arctwo.c

   1 /* arctwo.c
   2  *
   3  * The cipher described in rfc2268; aka Ron's Cipher 2.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2004 Simon Josefsson
   9  * Copyright (C) 2003 Nikos Mavroyanopoulos
  10  * Copyright (C) 2004 Free Software Foundation, Inc.
  11  * Copyright (C) 2004 Niels Möller
  12  *
  13  * The nettle library is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU Lesser General Public License as published by
  15  * the Free Software Foundation; either version 2.1 of the License, or (at your
  16  * option) any later version.
  17  *
  18  * The nettle library is distributed in the hope that it will be useful, but
  19  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  20  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  21  * License for more details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public License
  24  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  25  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  26  * MA 02111-1301, USA.
  27  */
  28
  29 /* This implementation was written by Nikos Mavroyanopoulos for GNUTLS
  30  * as a Libgcrypt module (gnutls/lib/x509/rc2.c) and later adapted for
  31  * direct use by Libgcrypt by Werner Koch and later adapted for direct
  32  * use by Nettle by Simon Josefsson and Niels Möller.
  33  *
  34  * The implementation here is based on Peter Gutmann's RRC.2 paper and
  35  * RFC 2268.
  36  */
  37
  38 #if HAVE_CONFIG_H
  39 # include "config.h"
  40 #endif
  41
  42 #include <assert.h>
  43
  44 #include "arctwo.h"
  45
  46 #include "macros.h"
  47
  48 static const uint8_t arctwo_sbox[] = {
  49   0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed,
  50   0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d,
  51   0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e,
  52   0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2,
  53   0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13,
  54   0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
  55   0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b,
  56   0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82,
  57   0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c,
  58   0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc,
  59   0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1,
  60   0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
  61   0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57,
  62   0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03,
  63   0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7,
  64   0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7,
  65   0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7,
  66   0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
  67   0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74,
  68   0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec,
  69   0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc,
  70   0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39,
  71   0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a,
  72   0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
  73   0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae,
  74   0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9,
  75   0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c,
  76   0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9,
  77   0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0,
  78   0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
  79   0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77,
  80   0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad
  81 };
  82
  83 #define rotl16(x,n) (((x) << ((uint16_t)(n))) | ((x) >> (16 - (uint16_t)(n))))
  84 #define rotr16(x,n) (((x) >> ((uint16_t)(n))) | ((x) << (16 - (uint16_t)(n))))
  85
  86 void
  87 arctwo_encrypt (struct arctwo_ctx *ctx,
  88                 unsigned length, uint8_t *dst, const uint8_t *src)
  89 {
  90   FOR_BLOCKS (length, dst, src, ARCTWO_BLOCK_SIZE)
  91   {
  92     register unsigned i;
  93     uint16_t w0, w1, w2, w3;
  94
  95     w0 = LE_READ_UINT16 (&src[0]);
  96     w1 = LE_READ_UINT16 (&src[2]);
  97     w2 = LE_READ_UINT16 (&src[4]);
  98     w3 = LE_READ_UINT16 (&src[6]);
  99
 100     for (i = 0; i < 16; i++)
 101       {
 102         register unsigned j = i * 4;
 103         /* For some reason I cannot combine those steps. */
 104         w0 += (w1 & ~w3) + (w2 & w3) + ctx->S[j];
 105         w0 = rotl16 (w0, 1);
 106
 107         w1 += (w2 & ~w0) + (w3 & w0) + ctx->S[j + 1];
 108         w1 = rotl16 (w1, 2);
 109
 110         w2 += (w3 & ~w1) + (w0 & w1) + ctx->S[j + 2];
 111         w2 = rotl16 (w2, 3);
 112
 113         w3 += (w0 & ~w2) + (w1 & w2) + ctx->S[j + 3];
 114         w3 = rotl16 (w3, 5);
 115
 116         if (i == 4 || i == 10)
 117           {
 118             w0 += ctx->S[w3 & 63];
 119             w1 += ctx->S[w0 & 63];
 120             w2 += ctx->S[w1 & 63];
 121             w3 += ctx->S[w2 & 63];
 122           }
 123       }
 124     LE_WRITE_UINT16 (&dst[0], w0);
 125     LE_WRITE_UINT16 (&dst[2], w1);
 126     LE_WRITE_UINT16 (&dst[4], w2);
 127     LE_WRITE_UINT16 (&dst[6], w3);
 128   }
 129 }
 130
 131 void
 132 arctwo_decrypt (struct arctwo_ctx *ctx,
 133                 unsigned length, uint8_t *dst, const uint8_t *src)
 134 {
 135   FOR_BLOCKS (length, dst, src, ARCTWO_BLOCK_SIZE)
 136   {
 137     register unsigned i;
 138     uint16_t w0, w1, w2, w3;
 139
 140     w0 = LE_READ_UINT16 (&src[0]);
 141     w1 = LE_READ_UINT16 (&src[2]);
 142     w2 = LE_READ_UINT16 (&src[4]);
 143     w3 = LE_READ_UINT16 (&src[6]);
 144
 145     for (i = 16; i-- > 0; )
 146       {
 147         register unsigned j = i * 4;
 148
 149         w3 = rotr16 (w3, 5);
 150         w3 -= (w0 & ~w2) + (w1 & w2) + ctx->S[j + 3];
 151
 152         w2 = rotr16 (w2, 3);
 153         w2 -= (w3 & ~w1) + (w0 & w1) + ctx->S[j + 2];
 154
 155         w1 = rotr16 (w1, 2);
 156         w1 -= (w2 & ~w0) + (w3 & w0) + ctx->S[j + 1];
 157
 158         w0 = rotr16 (w0, 1);
 159         w0 -= (w1 & ~w3) + (w2 & w3) + ctx->S[j];
 160
 161         if (i == 5 || i == 11)
 162           {
 163             w3 = w3 - ctx->S[w2 & 63];
 164             w2 = w2 - ctx->S[w1 & 63];
 165             w1 = w1 - ctx->S[w0 & 63];
 166             w0 = w0 - ctx->S[w3 & 63];
 167           }
 168
 169       }
 170     LE_WRITE_UINT16 (&dst[0], w0);
 171     LE_WRITE_UINT16 (&dst[2], w1);
 172     LE_WRITE_UINT16 (&dst[4], w2);
 173     LE_WRITE_UINT16 (&dst[6], w3);
 174   }
 175 }
 176
 177 void
 178 arctwo_set_key_ekb (struct arctwo_ctx *ctx,
 179                     unsigned length, const uint8_t *key, unsigned ekb)
 180 {
 181   unsigned i;
 182   /* Expanded key, treated as octets */
 183   uint8_t S[128];
 184   uint8_t x;
 185
 186   assert (length >= ARCTWO_MIN_KEY_SIZE);
 187   assert (length <= ARCTWO_MAX_KEY_SIZE);
 188   assert (ekb <= 1024);
 189
 190   for (i = 0; i < length; i++)
 191     S[i] = key[i];
 192
 193   /* Phase 1: Expand input key to 128 bytes */
 194   for (i = length; i < ARCTWO_MAX_KEY_SIZE; i++)
 195     S[i] = arctwo_sbox[(S[i - length] + S[i - 1]) & 255];
 196
 197   S[0] = arctwo_sbox[S[0]];
 198
 199   /* Reduce effective key size to ekb bits, if requested by caller. */
 200   if (ekb > 0 && ekb < 1024)
 201     {
 202       int len = (ekb + 7) >> 3;
 203       i = 128 - len;
 204       x = arctwo_sbox[S[i] & (255 >> (7 & -ekb))];
 205       S[i] = x;
 206
 207       while (i--)
 208         {
 209           x = arctwo_sbox[x ^ S[i + len]];
 210           S[i] = x;
 211         }
 212     }
 213
 214   /* Make the expanded key endian independent. */
 215   for (i = 0; i < 64; i++)
 216     ctx->S[i] = LE_READ_UINT16(S + i * 2);
 217 }
 218
 219 void
 220 arctwo_set_key (struct arctwo_ctx *ctx, unsigned length, const uint8_t *key)
 221 {
 222   arctwo_set_key_ekb (ctx, length, key, 8 * length);
 223 }
 224
 225 void
 226 arctwo_set_key_gutmann (struct arctwo_ctx *ctx,
 227                         unsigned length, const uint8_t *key)
 228 {
 229   arctwo_set_key_ekb (ctx, length, key, 0);
 230 }