| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rc4.c,v 1.1 1999/09/03 08:41:12 mdw Exp $ |
| 4 | * |
| 5 | * The alleged RC4 stream cipher |
| 6 | * |
| 7 | * (c) 1999 Straylight/Edgeware |
| 8 | */ |
| 9 | |
| 10 | /*----- Licensing notice --------------------------------------------------* |
| 11 | * |
| 12 | * This file is part of Catacomb. |
| 13 | * |
| 14 | * Catacomb is free software; you can redistribute it and/or modify |
| 15 | * it under the terms of the GNU Library General Public License as |
| 16 | * published by the Free Software Foundation; either version 2 of the |
| 17 | * License, or (at your option) any later version. |
| 18 | * |
| 19 | * Catacomb is distributed in the hope that it will be useful, |
| 20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 22 | * GNU Library General Public License for more details. |
| 23 | * |
| 24 | * You should have received a copy of the GNU Library General Public |
| 25 | * License along with Catacomb; if not, write to the Free |
| 26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 27 | * MA 02111-1307, USA. |
| 28 | */ |
| 29 | |
| 30 | /*----- Revision history --------------------------------------------------* |
| 31 | * |
| 32 | * $Log: rc4.c,v $ |
| 33 | * Revision 1.1 1999/09/03 08:41:12 mdw |
| 34 | * Initial import. |
| 35 | * |
| 36 | */ |
| 37 | |
| 38 | /*----- Header files ------------------------------------------------------*/ |
| 39 | |
| 40 | #include <assert.h> |
| 41 | #include <stdio.h> |
| 42 | |
| 43 | #include <mLib/bits.h> |
| 44 | |
| 45 | #include "rc4.h" |
| 46 | |
| 47 | /*----- Main code ---------------------------------------------------------*/ |
| 48 | |
| 49 | /* --- @rc4_init@ --- * |
| 50 | * |
| 51 | * Arguments: @rc4_ctx *ctx@ = pointer to context to initialize |
| 52 | * @const void *k@ = pointer to key data to use |
| 53 | * @size_t sz@ = size of the key data |
| 54 | * |
| 55 | * Returns: --- |
| 56 | * |
| 57 | * Use: Initializes an RC4 context ready for use. |
| 58 | */ |
| 59 | |
| 60 | void rc4_init(rc4_ctx *ctx, const void *k, size_t sz) |
| 61 | { |
| 62 | unsigned i, j; |
| 63 | const octet *p = k, *q = p + sz; |
| 64 | |
| 65 | assert(((void)"RC4 does not support zero length keys", sz != 0)); |
| 66 | |
| 67 | for (i = 0; i < 256; i++) |
| 68 | ctx->s[i] = i; |
| 69 | ctx->f = 0; |
| 70 | ctx->i = ctx->j = 0; |
| 71 | |
| 72 | for (i = j = 0; i < 256; i++) { |
| 73 | unsigned si = ctx->s[i]; |
| 74 | j = (j + si + *p++) & 0xff; |
| 75 | ctx->s[i] = ctx->s[j]; |
| 76 | ctx->s[j] = si; |
| 77 | if (p == q) |
| 78 | p = k; |
| 79 | } |
| 80 | |
| 81 | #ifdef notdef |
| 82 | for (i = 0; i < 256; i += 16) { |
| 83 | printf("%3d :", i); |
| 84 | for (j = i; j < i + 16; j++) |
| 85 | printf(" %02x", ctx->s[j]); |
| 86 | putchar('\n'); |
| 87 | } |
| 88 | #endif |
| 89 | } |
| 90 | |
| 91 | /* --- @rc4_encrypt@ --- * |
| 92 | * |
| 93 | * Arguments: @rc4_ctx *ctx@ = pointer to context to use |
| 94 | * @const void *src@ = pointer to the source block |
| 95 | * @void *dest@ = pointer to the destination block |
| 96 | * @size_t sz@ = size of the block |
| 97 | * |
| 98 | * Returns: --- |
| 99 | * |
| 100 | * Use: Encrypts or decrypts a block of data. The destination may |
| 101 | * be null to just grind the generator around for a while. It's |
| 102 | * recommended that you say `@rc4_encrypt(&ctx, 0, 0, 1024)@' |
| 103 | * after initializing a new context, to prevent keystream |
| 104 | * guessing attacks. The source may be null to just extract a |
| 105 | * big lump of data from the generator. |
| 106 | */ |
| 107 | |
| 108 | void rc4_encrypt(rc4_ctx *ctx, const void *src, void *dest, size_t sz) |
| 109 | { |
| 110 | const octet *s = src; |
| 111 | octet *d = dest; |
| 112 | |
| 113 | if (!d) |
| 114 | RC4_OPEN(ctx, while (sz) { unsigned x; RC4_BYTE(x); sz--; }); |
| 115 | else if (!s) |
| 116 | RC4_OPEN(ctx, while (sz) { RC4_BYTE(*d++); sz--; }); |
| 117 | else |
| 118 | RC4_OPEN(ctx, |
| 119 | while (sz) { unsigned x; RC4_BYTE(x); *d++ = *s++ ^ x; sz--; }); |
| 120 | } |
| 121 | |
| 122 | /*----- Test rig ----------------------------------------------------------*/ |
| 123 | |
| 124 | #ifdef TEST_RIG |
| 125 | |
| 126 | #include <stdio.h> |
| 127 | #include <string.h> |
| 128 | |
| 129 | #include <mLib/quis.h> |
| 130 | #include <mLib/testrig.h> |
| 131 | |
| 132 | static int v_encrypt(dstr *v) |
| 133 | { |
| 134 | rc4_ctx ctx; |
| 135 | dstr d = DSTR_INIT; |
| 136 | int ok = 1; |
| 137 | |
| 138 | rc4_init(&ctx, v[0].buf, v[0].len); |
| 139 | dstr_ensure(&d, v[1].len); |
| 140 | d.len = v[1].len; |
| 141 | rc4_encrypt(&ctx, v[1].buf, d.buf, d.len); |
| 142 | |
| 143 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
| 144 | ok = 0; |
| 145 | printf("\nfail encryption:" |
| 146 | "\n\tkey = "); |
| 147 | type_hex.dump(&v[0], stdout); |
| 148 | printf("\n\tplaintext = "); type_hex.dump(&v[1], stdout); |
| 149 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
| 150 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
| 151 | putchar('\n'); |
| 152 | } |
| 153 | |
| 154 | return (ok); |
| 155 | } |
| 156 | |
| 157 | static int v_generate(dstr *v) |
| 158 | { |
| 159 | rc4_ctx ctx; |
| 160 | dstr d = DSTR_INIT; |
| 161 | int ok = 1; |
| 162 | |
| 163 | rc4_init(&ctx, v[0].buf, v[0].len); |
| 164 | rc4_encrypt(&ctx, 0, 0, *(int *)v[1].buf); |
| 165 | dstr_ensure(&d, v[2].len); |
| 166 | d.len = v[2].len; |
| 167 | rc4_encrypt(&ctx, 0, d.buf, d.len); |
| 168 | |
| 169 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
| 170 | ok = 0; |
| 171 | printf("\nfail generation:" |
| 172 | "\n\tkey = "); |
| 173 | type_hex.dump(&v[0], stdout); |
| 174 | printf("\n\tskip len = %i", *(int *)v[1].buf); |
| 175 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
| 176 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
| 177 | putchar('\n'); |
| 178 | } |
| 179 | |
| 180 | return (ok); |
| 181 | } |
| 182 | |
| 183 | static test_chunk defs[] = { |
| 184 | { "rc4-encrypt", v_encrypt, { &type_hex, &type_hex, &type_hex, 0 } }, |
| 185 | { "rc4-generate", v_generate, { &type_hex, &type_int, &type_hex, 0 } }, |
| 186 | { 0, 0, { 0 } } |
| 187 | }; |
| 188 | |
| 189 | int main(int argc, char *argv[]) |
| 190 | { |
| 191 | test_run(argc, argv, defs, SRCDIR"/tests/rc4"); |
| 192 | return (0); |
| 193 | } |
| 194 | |
| 195 | #endif |
| 196 | |
| 197 | /*----- That's all, folks -------------------------------------------------*/ |