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[/] [tv80/] [trunk/] [tests/] [rc4.c] - Rev 96
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/* * rc4.c * * Copyright (c) 1996-2000 Whistle Communications, Inc. * All rights reserved. * * Subject to the following obligations and disclaimer of warranty, use and * redistribution of this software, in source or object code forms, with or * without modifications are expressly permitted by Whistle Communications; * provided, however, that: * 1. Any and all reproductions of the source or object code must include the * copyright notice above and the following disclaimer of warranties; and * 2. No rights are granted, in any manner or form, to use Whistle * Communications, Inc. trademarks, including the mark "WHISTLE * COMMUNICATIONS" on advertising, endorsements, or otherwise except as * such appears in the above copyright notice or in the software. * * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY * OF SUCH DAMAGE. */ #include <rc4.h> void swap_bytes(uint8_t *a, uint8_t *b) { /* _asm ld d,4(ix) ld e,5(ix) ld h,6(ix) ld l,7(ix) ld a, (de) ld b, a ld a, (hl) ld (de), a ld (hl), b _endasm; */ uint8_t temp; temp = *a; *a = *b; *b = temp; } /* * Initialize an RC4 state buffer using the supplied key, * which can have arbitrary length. */ void rc4_init(struct rc4_state *const state, const uint8_t *key, int keylen) { uint8_t j; int i; /* Initialize state with identity permutation */ #ifndef ORIGINAL_C _asm ld d, 4(ix) ld e, 5(ix) ld b, #255 state_init: ld h, #0 ld l, b add hl, de ld (hl), b djnz state_init ex de, hl ld (hl), #0 ex de, hl ld l, #0 ld h, #1 add hl, de ld (hl), #0 inc hl ld (hl), #0 _endasm; #else for (i = 0; i < 256; i++) state->perm[i] = (uint8_t)i; state->index1 = 0; state->index2 = 0; #endif /* Randomize the permutation using key data */ for (j = i = 0; i < 256; i++) { uint8_t tmp; j += state->perm[i] + key[i % keylen]; tmp = state->perm[i]; state->perm[i] = state->perm[j]; state->perm[j] = tmp; //swap_bytes(&state->perm[i], &state->perm[j]); } } /* * Encrypt some data using the supplied RC4 state buffer. * The input and output buffers may be the same buffer. * Since RC4 is a stream cypher, this function is used * for both encryption and decryption. */ void rc4_crypt(struct rc4_state *const state, const uint8_t *inbuf, uint8_t *outbuf, int buflen) { int i; uint8_t j; for (i = 0; i < buflen; i++) { /* Update modification indicies */ state->index1++; state->index2 += state->perm[state->index1]; /* Modify permutation */ swap_bytes(&state->perm[state->index1], &state->perm[state->index2]); /* Encrypt/decrypt next byte */ j = state->perm[state->index1] + state->perm[state->index2]; outbuf[i] = inbuf[i] ^ state->perm[j]; } }
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