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Added the arcfour cipher which is of use for GNUTLS.
According to the selftest, it does not yet work :-((.
This commit is contained in:
Werner Koch
parent
14974bc5d7
commit
b75f734a11
165
cipher/arcfour.c
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165
cipher/arcfour.c
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/* arcfour.c - The arcfour stream cipher
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* Copyright (C) 2000 Free Software Foundation, Inc.
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*
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* For a description of the algorithm, see:
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* Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996.
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* ISBN 0-471-11709-9. Pages 397 ff.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "types.h"
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#include "g10lib.h"
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#include "arcfour.h"
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static const char *selftest(void);
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typedef struct {
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int idx_i, idx_j;
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byte sbox[256];
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} ARCFOUR_context;
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static void
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encrypt_stream( ARCFOUR_context *ctx,
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byte *outbuf, const byte *inbuf, unsigned int length )
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{
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int t;
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int i = ctx->idx_i;
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int j = ctx->idx_j;
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byte *sbox = ctx->sbox;
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while ( length-- ) {
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i = (i+1) % 256;
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j = (j + sbox[i]) % 256;
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t = sbox[i]; sbox[i] = sbox[j]; sbox[j] = t;
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*outbuf++ = *inbuf++ ^ sbox[(sbox[i] + sbox[j]) % 256];
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}
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ctx->idx_i = i;
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ctx->idx_j = j;
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}
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static int
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arcfour_setkey( ARCFOUR_context *ctx, const byte *key, unsigned int keylen )
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{
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static int initialized;
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static const char* selftest_failed;
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int i, j;
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byte karr[256];
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if( !initialized ) {
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initialized = 1;
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selftest_failed = selftest();
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if( selftest_failed )
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fprintf(stderr,"ARCFOUR selftest failed (%s)\n", selftest_failed );
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}
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if( selftest_failed )
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return GCRYERR_SELFTEST;
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if( keylen < 40 )
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return GCRYERR_INV_KEYLEN;
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ctx->idx_i = ctx->idx_j = 0;
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for (i=0; i < 256; i++ )
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ctx->sbox[i] = i;
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for (i=0; i < 256; i++ )
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karr[i] = key[i%keylen];
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for (i=j=0; i < 256; i++ ) {
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int t;
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j = (j + ctx->sbox[i] + karr[i]) % 256;
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t = ctx->sbox[i];
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ctx->sbox[i] = ctx->sbox[j];
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ctx->sbox[j] = t;
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}
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memset( karr, 0, 256 );
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return 0;
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}
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static const char*
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selftest(void)
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{
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ARCFOUR_context ctx;
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byte scratch[16];
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/* Test vector from Cryptlib labeled there:
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* "from the State/Commerce Department" */
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static const byte key_1[] =
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{ 0x61, 0x8A, 0x63, 0xD2, 0xFB };
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static const byte plaintext_1[] =
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{ 0xDC, 0xEE, 0x4C, 0xF9, 0x2C };
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static const byte ciphertext_1[] =
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{ 0xF1, 0x38, 0x29, 0xC9, 0xDE };
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arcfour_setkey( &ctx, key_1, sizeof(key_1));
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encrypt_stream( &ctx, scratch, plaintext_1, sizeof(plaintext_1));
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if (memcmp (scratch, ciphertext_1, sizeof (ciphertext_1)))
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return "Arcfour encryption test 1 failed.";
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encrypt_stream(&ctx, scratch, scratch, sizeof(plaintext_1)); /* decrypt */
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if ( memcmp (scratch, plaintext_1, sizeof (plaintext_1)))
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return "Arcfour decryption test 1 failed.";
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return NULL;
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}
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/****************
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* Return some information about the algorithm. We need algo here to
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* distinguish different flavors of the algorithm.
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* Returns: A pointer to string describing the algorithm or NULL if
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* the ALGO is invalid.
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* NOTE: This is a special get_info function which is different from all
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* others because arcfour is a stream cipher. We use this hack until
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* we have redesign the interface.
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*/
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const char *
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arcfour_get_info( int algo, size_t *keylen, size_t *blocksize,
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size_t *contextsize,
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int (**r_setkey)( void *c, byte *key, unsigned keylen ),
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void (**r_stencrypt)( void *c, byte *outbuf,
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byte *inbuf, unsigned int nbytes ),
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void (**r_stdecrypt)( void *c, byte *outbuf,
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byte *inbuf, unsigned int nbytes )
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)
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{
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*keylen = 128; /* arbitrary value */
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*blocksize = 1;
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*contextsize = sizeof(ARCFOUR_context);
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*(int (**)(ARCFOUR_context*, byte*, unsigned))r_setkey
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= arcfour_setkey;
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*(void (**)(ARCFOUR_context*, byte*, const byte*, unsigned))r_stencrypt
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= encrypt_stream;
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*(void (**)(ARCFOUR_context*, byte*, const byte*, unsigned))r_stdecrypt
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= encrypt_stream;
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if( algo == 301 )
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return "ARCFOUR";
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return NULL;
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}
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41
cipher/arcfour.h
Normal file
41
cipher/arcfour.h
Normal file
@ -0,0 +1,41 @@
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/* arcfour.h
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* Copyright (C) 2000 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#ifndef G10_ARCFOUR_H
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#define G10_ARCFOUR_H
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#include "types.h"
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/* NOTE: This is a special get_info function which is different from all
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* others because arcfour is a stream cipher. We use this hack until
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* we have redesigned the interface.
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*/
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const char *
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arcfour_get_info( int algo, size_t *keylen, size_t *blocksize,
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size_t *contextsize,
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int (**r_setkey)( void *c, byte *key, unsigned keylen ),
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void (**r_stencrypt)( void *c, byte *outbuf,
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byte *inbuf, unsigned int nbytes ),
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void (**r_stdecrypt)( void *c, byte *outbuf,
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byte *inbuf, unsigned int nbytes )
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);
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#endif /*G10_ARCFOUR_H*/
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