1 /* $OpenBSD: rc4.c,v 1.10 2024/03/28 08:18:13 joshua Exp $ */ 2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay@cryptsoft.com). 7 * The implementation was written so as to conform with Netscapes SSL. 8 * 9 * This library is free for commercial and non-commercial use as long as 10 * the following conditions are aheared to. The following conditions 11 * apply to all code found in this distribution, be it the RC4, RSA, 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13 * included with this distribution is covered by the same copyright terms 14 * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15 * 16 * Copyright remains Eric Young's, and as such any Copyright notices in 17 * the code are not to be removed. 18 * If this package is used in a product, Eric Young should be given attribution 19 * as the author of the parts of the library used. 20 * This can be in the form of a textual message at program startup or 21 * in documentation (online or textual) provided with the package. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 3. All advertising materials mentioning features or use of this software 32 * must display the following acknowledgement: 33 * "This product includes cryptographic software written by 34 * Eric Young (eay@cryptsoft.com)" 35 * The word 'cryptographic' can be left out if the rouines from the library 36 * being used are not cryptographic related :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51 * SUCH DAMAGE. 52 * 53 * The licence and distribution terms for any publically available version or 54 * derivative of this code cannot be changed. i.e. this code cannot simply be 55 * copied and put under another distribution licence 56 * [including the GNU Public Licence.] 57 */ 58 59 #include <endian.h> 60 61 #include <openssl/rc4.h> 62 63 /* RC4 as implemented from a posting from 64 * Newsgroups: sci.crypt 65 * From: sterndark@netcom.com (David Sterndark) 66 * Subject: RC4 Algorithm revealed. 67 * Message-ID: <sternCvKL4B.Hyy@netcom.com> 68 * Date: Wed, 14 Sep 1994 06:35:31 GMT 69 */ 70 71 #ifdef HAVE_RC4_INTERNAL 72 void rc4_internal(RC4_KEY *key, size_t len, const unsigned char *indata, 73 unsigned char *outdata); 74 75 #else 76 static void 77 rc4_internal(RC4_KEY *key, size_t len, const unsigned char *indata, 78 unsigned char *outdata) 79 { 80 RC4_INT *d; 81 RC4_INT x, y,tx, ty; 82 size_t i; 83 84 x = key->x; 85 y = key->y; 86 d = key->data; 87 88 #if defined(RC4_CHUNK) 89 /* 90 * The original reason for implementing this(*) was the fact that 91 * pre-21164a Alpha CPUs don't have byte load/store instructions 92 * and e.g. a byte store has to be done with 64-bit load, shift, 93 * and, or and finally 64-bit store. Peaking data and operating 94 * at natural word size made it possible to reduce amount of 95 * instructions as well as to perform early read-ahead without 96 * suffering from RAW (read-after-write) hazard. This resulted 97 * in ~40%(**) performance improvement on 21064 box with gcc. 98 * But it's not only Alpha users who win here:-) Thanks to the 99 * early-n-wide read-ahead this implementation also exhibits 100 * >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending 101 * on sizeof(RC4_INT)). 102 * 103 * (*) "this" means code which recognizes the case when input 104 * and output pointers appear to be aligned at natural CPU 105 * word boundary 106 * (**) i.e. according to 'apps/openssl speed rc4' benchmark, 107 * crypto/rc4/rc4speed.c exhibits almost 70% speed-up... 108 * 109 * Caveats. 110 * 111 * - RC4_CHUNK="unsigned long long" should be a #1 choice for 112 * UltraSPARC. Unfortunately gcc generates very slow code 113 * (2.5-3 times slower than one generated by Sun's WorkShop 114 * C) and therefore gcc (at least 2.95 and earlier) should 115 * always be told that RC4_CHUNK="unsigned long". 116 * 117 * <appro@fy.chalmers.se> 118 */ 119 120 # define RC4_STEP ( \ 121 x=(x+1) &0xff, \ 122 tx=d[x], \ 123 y=(tx+y)&0xff, \ 124 ty=d[y], \ 125 d[y]=tx, \ 126 d[x]=ty, \ 127 (RC4_CHUNK)d[(tx+ty)&0xff]\ 128 ) 129 130 if ((((size_t)indata & (sizeof(RC4_CHUNK) - 1)) | 131 ((size_t)outdata & (sizeof(RC4_CHUNK) - 1))) == 0 ) { 132 RC4_CHUNK ichunk, otp; 133 134 /* 135 * I reckon we can afford to implement both endian 136 * cases and to decide which way to take at run-time 137 * because the machine code appears to be very compact 138 * and redundant 1-2KB is perfectly tolerable (i.e. 139 * in case the compiler fails to eliminate it:-). By 140 * suggestion from Terrel Larson <terr@terralogic.net>. 141 * 142 * Special notes. 143 * 144 * - compilers (those I've tried) don't seem to have 145 * problems eliminating either the operators guarded 146 * by "if (sizeof(RC4_CHUNK)==8)" or the condition 147 * expressions themselves so I've got 'em to replace 148 * corresponding #ifdefs from the previous version; 149 * - I chose to let the redundant switch cases when 150 * sizeof(RC4_CHUNK)!=8 be (were also #ifdefed 151 * before); 152 * - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in 153 * [LB]ESHFT guards against "shift is out of range" 154 * warnings when sizeof(RC4_CHUNK)!=8 155 * 156 * <appro@fy.chalmers.se> 157 */ 158 #if BYTE_ORDER == BIG_ENDIAN 159 # define BESHFT(c) (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1)) 160 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) { 161 ichunk = *(RC4_CHUNK *)indata; 162 otp = RC4_STEP << BESHFT(0); 163 otp |= RC4_STEP << BESHFT(1); 164 otp |= RC4_STEP << BESHFT(2); 165 otp |= RC4_STEP << BESHFT(3); 166 if (sizeof(RC4_CHUNK) == 8) { 167 otp |= RC4_STEP << BESHFT(4); 168 otp |= RC4_STEP << BESHFT(5); 169 otp |= RC4_STEP << BESHFT(6); 170 otp |= RC4_STEP << BESHFT(7); 171 } 172 *(RC4_CHUNK *)outdata = otp^ichunk; 173 indata += sizeof(RC4_CHUNK); 174 outdata += sizeof(RC4_CHUNK); 175 } 176 #else 177 # define LESHFT(c) (((c)*8)&(sizeof(RC4_CHUNK)*8-1)) 178 for (; len & (0 - sizeof(RC4_CHUNK)); len -= sizeof(RC4_CHUNK)) { 179 ichunk = *(RC4_CHUNK *)indata; 180 otp = RC4_STEP; 181 otp |= RC4_STEP << 8; 182 otp |= RC4_STEP << 16; 183 otp |= RC4_STEP << 24; 184 if (sizeof(RC4_CHUNK) == 8) { 185 otp |= RC4_STEP << LESHFT(4); 186 otp |= RC4_STEP << LESHFT(5); 187 otp |= RC4_STEP << LESHFT(6); 188 otp |= RC4_STEP << LESHFT(7); 189 } 190 *(RC4_CHUNK *)outdata = otp ^ ichunk; 191 indata += sizeof(RC4_CHUNK); 192 outdata += sizeof(RC4_CHUNK); 193 } 194 #endif 195 } 196 #endif 197 #define LOOP(in,out) \ 198 x=((x+1)&0xff); \ 199 tx=d[x]; \ 200 y=(tx+y)&0xff; \ 201 d[x]=ty=d[y]; \ 202 d[y]=tx; \ 203 (out) = d[(tx+ty)&0xff]^ (in); 204 205 #ifndef RC4_INDEX 206 #define RC4_LOOP(a,b,i) LOOP(*((a)++),*((b)++)) 207 #else 208 #define RC4_LOOP(a,b,i) LOOP(a[i],b[i]) 209 #endif 210 211 i = len >> 3; 212 if (i) { 213 for (;;) { 214 RC4_LOOP(indata, outdata, 0); 215 RC4_LOOP(indata, outdata, 1); 216 RC4_LOOP(indata, outdata, 2); 217 RC4_LOOP(indata, outdata, 3); 218 RC4_LOOP(indata, outdata, 4); 219 RC4_LOOP(indata, outdata, 5); 220 RC4_LOOP(indata, outdata, 6); 221 RC4_LOOP(indata, outdata, 7); 222 #ifdef RC4_INDEX 223 indata += 8; 224 outdata += 8; 225 #endif 226 if (--i == 0) 227 break; 228 } 229 } 230 i = len&0x07; 231 if (i) { 232 for (;;) { 233 RC4_LOOP(indata, outdata, 0); 234 if (--i == 0) 235 break; 236 RC4_LOOP(indata, outdata, 1); 237 if (--i == 0) 238 break; 239 RC4_LOOP(indata, outdata, 2); 240 if (--i == 0) 241 break; 242 RC4_LOOP(indata, outdata, 3); 243 if (--i == 0) 244 break; 245 RC4_LOOP(indata, outdata, 4); 246 if (--i == 0) 247 break; 248 RC4_LOOP(indata, outdata, 5); 249 if (--i == 0) 250 break; 251 RC4_LOOP(indata, outdata, 6); 252 if (--i == 0) 253 break; 254 } 255 } 256 key->x = x; 257 key->y = y; 258 } 259 #endif 260 261 #ifdef HAVE_RC4_SET_KEY_INTERNAL 262 void rc4_set_key_internal(RC4_KEY *key, int len, const unsigned char *data); 263 264 #else 265 static void 266 rc4_set_key_internal(RC4_KEY *key, int len, const unsigned char *data) 267 { 268 RC4_INT tmp; 269 int id1, id2; 270 RC4_INT *d; 271 unsigned int i; 272 273 d = &(key->data[0]); 274 key->x = 0; 275 key->y = 0; 276 id1 = id2 = 0; 277 278 #define SK_LOOP(d,n) { \ 279 tmp=d[(n)]; \ 280 id2 = (data[id1] + tmp + id2) & 0xff; \ 281 if (++id1 == len) id1=0; \ 282 d[(n)]=d[id2]; \ 283 d[id2]=tmp; } 284 285 for (i = 0; i < 256; i++) 286 d[i] = i; 287 for (i = 0; i < 256; i += 4) { 288 SK_LOOP(d, i + 0); 289 SK_LOOP(d, i + 1); 290 SK_LOOP(d, i + 2); 291 SK_LOOP(d, i + 3); 292 } 293 } 294 #endif 295 296 void 297 RC4(RC4_KEY *key, size_t len, const unsigned char *indata, 298 unsigned char *outdata) 299 { 300 rc4_internal(key, len, indata, outdata); 301 } 302 LCRYPTO_ALIAS(RC4); 303 304 void 305 RC4_set_key(RC4_KEY *key, int len, const unsigned char *data) 306 { 307 rc4_set_key_internal(key, len, data); 308 } 309 LCRYPTO_ALIAS(RC4_set_key); 310