180 lines
3.7 KiB
C
180 lines
3.7 KiB
C
/*
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* An implementation of the ARCFOUR algorithm
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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/*
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* The ARCFOUR algorithm was publicly disclosed on 94/09.
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*
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* http://groups.google.com/group/sci.crypt/msg/10a300c9d21afca0
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*/
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#include "common.h"
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#if defined(MBEDTLS_ARC4_C)
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#include "mbedtls/arc4.h"
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#include "mbedtls/platform_util.h"
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#include <string.h>
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#include "mbedtls/platform.h"
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#if !defined(MBEDTLS_ARC4_ALT)
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void mbedtls_arc4_init(mbedtls_arc4_context *ctx)
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{
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memset(ctx, 0, sizeof(mbedtls_arc4_context));
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}
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void mbedtls_arc4_free(mbedtls_arc4_context *ctx)
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{
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if (ctx == NULL) {
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return;
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}
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mbedtls_platform_zeroize(ctx, sizeof(mbedtls_arc4_context));
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}
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/*
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* ARC4 key schedule
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*/
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void mbedtls_arc4_setup(mbedtls_arc4_context *ctx, const unsigned char *key,
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unsigned int keylen)
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{
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int i, j, a;
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unsigned int k;
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unsigned char *m;
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ctx->x = 0;
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ctx->y = 0;
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m = ctx->m;
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for (i = 0; i < 256; i++) {
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m[i] = (unsigned char) i;
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}
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j = k = 0;
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for (i = 0; i < 256; i++, k++) {
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if (k >= keylen) {
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k = 0;
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}
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a = m[i];
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j = (j + a + key[k]) & 0xFF;
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m[i] = m[j];
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m[j] = (unsigned char) a;
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}
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}
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/*
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* ARC4 cipher function
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*/
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int mbedtls_arc4_crypt(mbedtls_arc4_context *ctx, size_t length, const unsigned char *input,
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unsigned char *output)
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{
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int x, y, a, b;
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size_t i;
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unsigned char *m;
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x = ctx->x;
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y = ctx->y;
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m = ctx->m;
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for (i = 0; i < length; i++) {
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x = (x + 1) & 0xFF; a = m[x];
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y = (y + a) & 0xFF; b = m[y];
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m[x] = (unsigned char) b;
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m[y] = (unsigned char) a;
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output[i] = (unsigned char)
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(input[i] ^ m[(unsigned char) (a + b)]);
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}
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ctx->x = x;
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ctx->y = y;
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return 0;
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}
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#endif /* !MBEDTLS_ARC4_ALT */
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#if defined(MBEDTLS_SELF_TEST)
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/*
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* ARC4 tests vectors as posted by Eric Rescorla in sep. 1994:
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*
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* http://groups.google.com/group/comp.security.misc/msg/10a300c9d21afca0
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*/
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static const unsigned char arc4_test_key[3][8] =
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{
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{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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};
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static const unsigned char arc4_test_pt[3][8] =
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{
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{ 0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 },
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{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
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};
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static const unsigned char arc4_test_ct[3][8] =
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{
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{ 0x75, 0xB7, 0x87, 0x80, 0x99, 0xE0, 0xC5, 0x96 },
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{ 0x74, 0x94, 0xC2, 0xE7, 0x10, 0x4B, 0x08, 0x79 },
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{ 0xDE, 0x18, 0x89, 0x41, 0xA3, 0x37, 0x5D, 0x3A }
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};
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/*
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* Checkup routine
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*/
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int mbedtls_arc4_self_test(int verbose)
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{
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int i, ret = 0;
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unsigned char ibuf[8];
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unsigned char obuf[8];
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mbedtls_arc4_context ctx;
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mbedtls_arc4_init(&ctx);
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for (i = 0; i < 3; i++) {
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if (verbose != 0) {
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mbedtls_printf(" ARC4 test #%d: ", i + 1);
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}
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memcpy(ibuf, arc4_test_pt[i], 8);
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mbedtls_arc4_setup(&ctx, arc4_test_key[i], 8);
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mbedtls_arc4_crypt(&ctx, 8, ibuf, obuf);
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if (memcmp(obuf, arc4_test_ct[i], 8) != 0) {
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if (verbose != 0) {
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mbedtls_printf("failed\n");
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}
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ret = 1;
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goto exit;
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}
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if (verbose != 0) {
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mbedtls_printf("passed\n");
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}
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}
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if (verbose != 0) {
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mbedtls_printf("\n");
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}
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exit:
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mbedtls_arc4_free(&ctx);
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return ret;
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}
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#endif /* MBEDTLS_SELF_TEST */
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#endif /* MBEDTLS_ARC4_C */
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