1 /* 2 * Copyright 2008-2021 The OpenSSL Project Authors. All Rights Reserved. 3 * 4 * Licensed under the Apache License 2.0 (the "License"). You may not use 5 * this file except in compliance with the License. You can obtain a copy 6 * in the file LICENSE in the source distribution or at 7 * https://www.openssl.org/source/license.html 8 */ 9 10 #include <string.h> 11 #include <openssl/crypto.h> 12 #include "crypto/modes.h" 13 14 #if defined(__GNUC__) && !defined(STRICT_ALIGNMENT) 15 typedef size_t size_t_aX __attribute((__aligned__(1))); 16 #else 17 typedef size_t size_t_aX; 18 #endif 19 20 /* 21 * The input and output encrypted as though 128bit ofb mode is being used. 22 * The extra state information to record how much of the 128bit block we have 23 * used is contained in *num; 24 */ 25 void CRYPTO_ofb128_encrypt(const unsigned char *in, unsigned char *out, 26 size_t len, const void *key, 27 unsigned char ivec[16], int *num, block128_f block) 28 { 29 unsigned int n; 30 size_t l = 0; 31 32 if (*num < 0) { 33 /* There is no good way to signal an error return from here */ 34 *num = -1; 35 return; 36 } 37 n = *num; 38 39 #if !defined(OPENSSL_SMALL_FOOTPRINT) 40 if (16 % sizeof(size_t) == 0) { /* always true actually */ 41 do { 42 while (n && len) { 43 *(out++) = *(in++) ^ ivec[n]; 44 --len; 45 n = (n + 1) % 16; 46 } 47 # if defined(STRICT_ALIGNMENT) 48 if (((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 49 0) 50 break; 51 # endif 52 while (len >= 16) { 53 (*block) (ivec, ivec, key); 54 for (; n < 16; n += sizeof(size_t)) 55 *(size_t_aX *)(out + n) = 56 *(size_t_aX *)(in + n) 57 ^ *(size_t_aX *)(ivec + n); 58 len -= 16; 59 out += 16; 60 in += 16; 61 n = 0; 62 } 63 if (len) { 64 (*block) (ivec, ivec, key); 65 while (len--) { 66 out[n] = in[n] ^ ivec[n]; 67 ++n; 68 } 69 } 70 *num = n; 71 return; 72 } while (0); 73 } 74 /* the rest would be commonly eliminated by x86* compiler */ 75 #endif 76 while (l < len) { 77 if (n == 0) { 78 (*block) (ivec, ivec, key); 79 } 80 out[l] = in[l] ^ ivec[n]; 81 ++l; 82 n = (n + 1) % 16; 83 } 84 85 *num = n; 86 } 87