diff --git a/cipher/arcfour.c b/cipher/arcfour.c new file mode 100644 index 000000000..61d0d2988 --- /dev/null +++ b/cipher/arcfour.c @@ -0,0 +1,165 @@ +/* arcfour.c - The arcfour stream cipher + * Copyright (C) 2000 Free Software Foundation, Inc. + * + * For a description of the algorithm, see: + * Bruce Schneier: Applied Cryptography. John Wiley & Sons, 1996. + * ISBN 0-471-11709-9. Pages 397 ff. + * + * This file is part of GnuPG. + * + * GnuPG is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * GnuPG is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ + + +#include +#include +#include +#include +#include "types.h" +#include "g10lib.h" +#include "arcfour.h" + +static const char *selftest(void); + + +typedef struct { + int idx_i, idx_j; + byte sbox[256]; +} ARCFOUR_context; + + +static void +encrypt_stream( ARCFOUR_context *ctx, + byte *outbuf, const byte *inbuf, unsigned int length ) +{ + int t; + int i = ctx->idx_i; + int j = ctx->idx_j; + byte *sbox = ctx->sbox; + + while ( length-- ) { + i = (i+1) % 256; + j = (j + sbox[i]) % 256; + t = sbox[i]; sbox[i] = sbox[j]; sbox[j] = t; + *outbuf++ = *inbuf++ ^ sbox[(sbox[i] + sbox[j]) % 256]; + } + + ctx->idx_i = i; + ctx->idx_j = j; +} + + +static int +arcfour_setkey( ARCFOUR_context *ctx, const byte *key, unsigned int keylen ) +{ + static int initialized; + static const char* selftest_failed; + int i, j; + byte karr[256]; + + if( !initialized ) { + initialized = 1; + selftest_failed = selftest(); + if( selftest_failed ) + fprintf(stderr,"ARCFOUR selftest failed (%s)\n", selftest_failed ); + } + if( selftest_failed ) + return GCRYERR_SELFTEST; + + if( keylen < 40 ) + return GCRYERR_INV_KEYLEN; + + ctx->idx_i = ctx->idx_j = 0; + for (i=0; i < 256; i++ ) + ctx->sbox[i] = i; + for (i=0; i < 256; i++ ) + karr[i] = key[i%keylen]; + for (i=j=0; i < 256; i++ ) { + int t; + j = (j + ctx->sbox[i] + karr[i]) % 256; + t = ctx->sbox[i]; + ctx->sbox[i] = ctx->sbox[j]; + ctx->sbox[j] = t; + } + memset( karr, 0, 256 ); + + return 0; +} + + +static const char* +selftest(void) +{ + ARCFOUR_context ctx; + byte scratch[16]; + + /* Test vector from Cryptlib labeled there: + * "from the State/Commerce Department" */ + static const byte key_1[] = + { 0x61, 0x8A, 0x63, 0xD2, 0xFB }; + static const byte plaintext_1[] = + { 0xDC, 0xEE, 0x4C, 0xF9, 0x2C }; + static const byte ciphertext_1[] = + { 0xF1, 0x38, 0x29, 0xC9, 0xDE }; + + arcfour_setkey( &ctx, key_1, sizeof(key_1)); + encrypt_stream( &ctx, scratch, plaintext_1, sizeof(plaintext_1)); + if (memcmp (scratch, ciphertext_1, sizeof (ciphertext_1))) + return "Arcfour encryption test 1 failed."; + encrypt_stream(&ctx, scratch, scratch, sizeof(plaintext_1)); /* decrypt */ + if ( memcmp (scratch, plaintext_1, sizeof (plaintext_1))) + return "Arcfour decryption test 1 failed."; + return NULL; +} + + +/**************** + * Return some information about the algorithm. We need algo here to + * distinguish different flavors of the algorithm. + * Returns: A pointer to string describing the algorithm or NULL if + * the ALGO is invalid. + * NOTE: This is a special get_info function which is different from all + * others because arcfour is a stream cipher. We use this hack until + * we have redesign the interface. + */ +const char * +arcfour_get_info( int algo, size_t *keylen, size_t *blocksize, + size_t *contextsize, + int (**r_setkey)( void *c, byte *key, unsigned keylen ), + void (**r_stencrypt)( void *c, byte *outbuf, + byte *inbuf, unsigned int nbytes ), + void (**r_stdecrypt)( void *c, byte *outbuf, + byte *inbuf, unsigned int nbytes ) + ) +{ + *keylen = 128; /* arbitrary value */ + *blocksize = 1; + *contextsize = sizeof(ARCFOUR_context); + *(int (**)(ARCFOUR_context*, byte*, unsigned))r_setkey + = arcfour_setkey; + *(void (**)(ARCFOUR_context*, byte*, const byte*, unsigned))r_stencrypt + = encrypt_stream; + *(void (**)(ARCFOUR_context*, byte*, const byte*, unsigned))r_stdecrypt + = encrypt_stream; + + + if( algo == 301 ) + return "ARCFOUR"; + return NULL; +} + + + + diff --git a/cipher/arcfour.h b/cipher/arcfour.h new file mode 100644 index 000000000..a4f1cb59b --- /dev/null +++ b/cipher/arcfour.h @@ -0,0 +1,41 @@ +/* arcfour.h + * Copyright (C) 2000 Free Software Foundation, Inc. + * + * This file is part of GnuPG. + * + * GnuPG is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * GnuPG is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ +#ifndef G10_ARCFOUR_H +#define G10_ARCFOUR_H + +#include "types.h" + +/* NOTE: This is a special get_info function which is different from all + * others because arcfour is a stream cipher. We use this hack until + * we have redesigned the interface. + */ +const char * +arcfour_get_info( int algo, size_t *keylen, size_t *blocksize, + size_t *contextsize, + int (**r_setkey)( void *c, byte *key, unsigned keylen ), + void (**r_stencrypt)( void *c, byte *outbuf, + byte *inbuf, unsigned int nbytes ), + void (**r_stdecrypt)( void *c, byte *outbuf, + byte *inbuf, unsigned int nbytes ) + ); + + +#endif /*G10_ARCFOUR_H*/ +