ctr128.c revision 238384
1238384Sjkim/* ==================================================================== 2238384Sjkim * Copyright (c) 2008 The OpenSSL Project. All rights reserved. 3238384Sjkim * 4238384Sjkim * Redistribution and use in source and binary forms, with or without 5238384Sjkim * modification, are permitted provided that the following conditions 6238384Sjkim * are met: 7238384Sjkim * 8238384Sjkim * 1. Redistributions of source code must retain the above copyright 9238384Sjkim * notice, this list of conditions and the following disclaimer. 10238384Sjkim * 11238384Sjkim * 2. Redistributions in binary form must reproduce the above copyright 12238384Sjkim * notice, this list of conditions and the following disclaimer in 13238384Sjkim * the documentation and/or other materials provided with the 14238384Sjkim * distribution. 15238384Sjkim * 16238384Sjkim * 3. All advertising materials mentioning features or use of this 17238384Sjkim * software must display the following acknowledgment: 18238384Sjkim * "This product includes software developed by the OpenSSL Project 19238384Sjkim * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 20238384Sjkim * 21238384Sjkim * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 22238384Sjkim * endorse or promote products derived from this software without 23238384Sjkim * prior written permission. For written permission, please contact 24238384Sjkim * openssl-core@openssl.org. 25238384Sjkim * 26238384Sjkim * 5. Products derived from this software may not be called "OpenSSL" 27238384Sjkim * nor may "OpenSSL" appear in their names without prior written 28238384Sjkim * permission of the OpenSSL Project. 29238384Sjkim * 30238384Sjkim * 6. Redistributions of any form whatsoever must retain the following 31238384Sjkim * acknowledgment: 32238384Sjkim * "This product includes software developed by the OpenSSL Project 33238384Sjkim * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 34238384Sjkim * 35238384Sjkim * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 36238384Sjkim * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 37238384Sjkim * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 38238384Sjkim * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 39238384Sjkim * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 40238384Sjkim * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 41238384Sjkim * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 42238384Sjkim * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 43238384Sjkim * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 44238384Sjkim * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 45238384Sjkim * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 46238384Sjkim * OF THE POSSIBILITY OF SUCH DAMAGE. 47238384Sjkim * ==================================================================== 48238384Sjkim * 49238384Sjkim */ 50238384Sjkim 51238384Sjkim#include <openssl/crypto.h> 52238384Sjkim#include "modes_lcl.h" 53238384Sjkim#include <string.h> 54238384Sjkim 55238384Sjkim#ifndef MODES_DEBUG 56238384Sjkim# ifndef NDEBUG 57238384Sjkim# define NDEBUG 58238384Sjkim# endif 59238384Sjkim#endif 60238384Sjkim#include <assert.h> 61238384Sjkim 62238384Sjkim/* NOTE: the IV/counter CTR mode is big-endian. The code itself 63238384Sjkim * is endian-neutral. */ 64238384Sjkim 65238384Sjkim/* increment counter (128-bit int) by 1 */ 66238384Sjkimstatic void ctr128_inc(unsigned char *counter) { 67238384Sjkim u32 n=16; 68238384Sjkim u8 c; 69238384Sjkim 70238384Sjkim do { 71238384Sjkim --n; 72238384Sjkim c = counter[n]; 73238384Sjkim ++c; 74238384Sjkim counter[n] = c; 75238384Sjkim if (c) return; 76238384Sjkim } while (n); 77238384Sjkim} 78238384Sjkim 79238384Sjkim#if !defined(OPENSSL_SMALL_FOOTPRINT) 80238384Sjkimstatic void ctr128_inc_aligned(unsigned char *counter) { 81238384Sjkim size_t *data,c,n; 82238384Sjkim const union { long one; char little; } is_endian = {1}; 83238384Sjkim 84238384Sjkim if (is_endian.little) { 85238384Sjkim ctr128_inc(counter); 86238384Sjkim return; 87238384Sjkim } 88238384Sjkim 89238384Sjkim data = (size_t *)counter; 90238384Sjkim n = 16/sizeof(size_t); 91238384Sjkim do { 92238384Sjkim --n; 93238384Sjkim c = data[n]; 94238384Sjkim ++c; 95238384Sjkim data[n] = c; 96238384Sjkim if (c) return; 97238384Sjkim } while (n); 98238384Sjkim} 99238384Sjkim#endif 100238384Sjkim 101238384Sjkim/* The input encrypted as though 128bit counter mode is being 102238384Sjkim * used. The extra state information to record how much of the 103238384Sjkim * 128bit block we have used is contained in *num, and the 104238384Sjkim * encrypted counter is kept in ecount_buf. Both *num and 105238384Sjkim * ecount_buf must be initialised with zeros before the first 106238384Sjkim * call to CRYPTO_ctr128_encrypt(). 107238384Sjkim * 108238384Sjkim * This algorithm assumes that the counter is in the x lower bits 109238384Sjkim * of the IV (ivec), and that the application has full control over 110238384Sjkim * overflow and the rest of the IV. This implementation takes NO 111238384Sjkim * responsability for checking that the counter doesn't overflow 112238384Sjkim * into the rest of the IV when incremented. 113238384Sjkim */ 114238384Sjkimvoid CRYPTO_ctr128_encrypt(const unsigned char *in, unsigned char *out, 115238384Sjkim size_t len, const void *key, 116238384Sjkim unsigned char ivec[16], unsigned char ecount_buf[16], 117238384Sjkim unsigned int *num, block128_f block) 118238384Sjkim{ 119238384Sjkim unsigned int n; 120238384Sjkim size_t l=0; 121238384Sjkim 122238384Sjkim assert(in && out && key && ecount_buf && num); 123238384Sjkim assert(*num < 16); 124238384Sjkim 125238384Sjkim n = *num; 126238384Sjkim 127238384Sjkim#if !defined(OPENSSL_SMALL_FOOTPRINT) 128238384Sjkim if (16%sizeof(size_t) == 0) do { /* always true actually */ 129238384Sjkim while (n && len) { 130238384Sjkim *(out++) = *(in++) ^ ecount_buf[n]; 131238384Sjkim --len; 132238384Sjkim n = (n+1) % 16; 133238384Sjkim } 134238384Sjkim 135238384Sjkim#if defined(STRICT_ALIGNMENT) 136238384Sjkim if (((size_t)in|(size_t)out|(size_t)ivec)%sizeof(size_t) != 0) 137238384Sjkim break; 138238384Sjkim#endif 139238384Sjkim while (len>=16) { 140238384Sjkim (*block)(ivec, ecount_buf, key); 141238384Sjkim ctr128_inc_aligned(ivec); 142238384Sjkim for (; n<16; n+=sizeof(size_t)) 143238384Sjkim *(size_t *)(out+n) = 144238384Sjkim *(size_t *)(in+n) ^ *(size_t *)(ecount_buf+n); 145238384Sjkim len -= 16; 146238384Sjkim out += 16; 147238384Sjkim in += 16; 148238384Sjkim n = 0; 149238384Sjkim } 150238384Sjkim if (len) { 151238384Sjkim (*block)(ivec, ecount_buf, key); 152238384Sjkim ctr128_inc_aligned(ivec); 153238384Sjkim while (len--) { 154238384Sjkim out[n] = in[n] ^ ecount_buf[n]; 155238384Sjkim ++n; 156238384Sjkim } 157238384Sjkim } 158238384Sjkim *num = n; 159238384Sjkim return; 160238384Sjkim } while(0); 161238384Sjkim /* the rest would be commonly eliminated by x86* compiler */ 162238384Sjkim#endif 163238384Sjkim while (l<len) { 164238384Sjkim if (n==0) { 165238384Sjkim (*block)(ivec, ecount_buf, key); 166238384Sjkim ctr128_inc(ivec); 167238384Sjkim } 168238384Sjkim out[l] = in[l] ^ ecount_buf[n]; 169238384Sjkim ++l; 170238384Sjkim n = (n+1) % 16; 171238384Sjkim } 172238384Sjkim 173238384Sjkim *num=n; 174238384Sjkim} 175238384Sjkim 176238384Sjkim/* increment upper 96 bits of 128-bit counter by 1 */ 177238384Sjkimstatic void ctr96_inc(unsigned char *counter) { 178238384Sjkim u32 n=12; 179238384Sjkim u8 c; 180238384Sjkim 181238384Sjkim do { 182238384Sjkim --n; 183238384Sjkim c = counter[n]; 184238384Sjkim ++c; 185238384Sjkim counter[n] = c; 186238384Sjkim if (c) return; 187238384Sjkim } while (n); 188238384Sjkim} 189238384Sjkim 190238384Sjkimvoid CRYPTO_ctr128_encrypt_ctr32(const unsigned char *in, unsigned char *out, 191238384Sjkim size_t len, const void *key, 192238384Sjkim unsigned char ivec[16], unsigned char ecount_buf[16], 193238384Sjkim unsigned int *num, ctr128_f func) 194238384Sjkim{ 195238384Sjkim unsigned int n,ctr32; 196238384Sjkim 197238384Sjkim assert(in && out && key && ecount_buf && num); 198238384Sjkim assert(*num < 16); 199238384Sjkim 200238384Sjkim n = *num; 201238384Sjkim 202238384Sjkim while (n && len) { 203238384Sjkim *(out++) = *(in++) ^ ecount_buf[n]; 204238384Sjkim --len; 205238384Sjkim n = (n+1) % 16; 206238384Sjkim } 207238384Sjkim 208238384Sjkim ctr32 = GETU32(ivec+12); 209238384Sjkim while (len>=16) { 210238384Sjkim size_t blocks = len/16; 211238384Sjkim /* 212238384Sjkim * 1<<28 is just a not-so-small yet not-so-large number... 213238384Sjkim * Below condition is practically never met, but it has to 214238384Sjkim * be checked for code correctness. 215238384Sjkim */ 216238384Sjkim if (sizeof(size_t)>sizeof(unsigned int) && blocks>(1U<<28)) 217238384Sjkim blocks = (1U<<28); 218238384Sjkim /* 219238384Sjkim * As (*func) operates on 32-bit counter, caller 220238384Sjkim * has to handle overflow. 'if' below detects the 221238384Sjkim * overflow, which is then handled by limiting the 222238384Sjkim * amount of blocks to the exact overflow point... 223238384Sjkim */ 224238384Sjkim ctr32 += (u32)blocks; 225238384Sjkim if (ctr32 < blocks) { 226238384Sjkim blocks -= ctr32; 227238384Sjkim ctr32 = 0; 228238384Sjkim } 229238384Sjkim (*func)(in,out,blocks,key,ivec); 230238384Sjkim /* (*ctr) does not update ivec, caller does: */ 231238384Sjkim PUTU32(ivec+12,ctr32); 232238384Sjkim /* ... overflow was detected, propogate carry. */ 233238384Sjkim if (ctr32 == 0) ctr96_inc(ivec); 234238384Sjkim blocks *= 16; 235238384Sjkim len -= blocks; 236238384Sjkim out += blocks; 237238384Sjkim in += blocks; 238238384Sjkim } 239238384Sjkim if (len) { 240238384Sjkim memset(ecount_buf,0,16); 241238384Sjkim (*func)(ecount_buf,ecount_buf,1,key,ivec); 242238384Sjkim ++ctr32; 243238384Sjkim PUTU32(ivec+12,ctr32); 244238384Sjkim if (ctr32 == 0) ctr96_inc(ivec); 245238384Sjkim while (len--) { 246238384Sjkim out[n] = in[n] ^ ecount_buf[n]; 247238384Sjkim ++n; 248238384Sjkim } 249238384Sjkim } 250238384Sjkim 251238384Sjkim *num=n; 252238384Sjkim} 253