1/* $OpenBSD: cipher-ctr.c,v 1.11 2010/10/01 23:05:32 djm Exp $ */ 2/* 3 * Copyright (c) 2003 Markus Friedl <markus@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17#include "includes.h" 18 19#ifndef OPENSSL_HAVE_EVPCTR 20#include <sys/types.h> 21 22#include <stdarg.h> 23#include <string.h> 24 25#ifdef __APPLE_CRYPTO__ 26#include "ossl-evp.h" 27#else 28#include <openssl/evp.h> 29#endif 30 31#include "xmalloc.h" 32#include "log.h" 33 34/* compatibility with old or broken OpenSSL versions */ 35#include "openbsd-compat/openssl-compat.h" 36 37#ifndef USE_BUILTIN_RIJNDAEL 38#ifdef __APPLE_CRYPTO__ 39#include "ossl-aes.h" 40#else 41#include <openssl/aes.h> 42#endif /* __APPLE_CRYPTO__ */ 43#endif 44 45struct ssh_aes_ctr_ctx 46{ 47 AES_KEY aes_ctx; 48 u_char aes_counter[AES_BLOCK_SIZE]; 49}; 50 51/* 52 * increment counter 'ctr', 53 * the counter is of size 'len' bytes and stored in network-byte-order. 54 * (LSB at ctr[len-1], MSB at ctr[0]) 55 */ 56static void 57ssh_ctr_inc(u_char *ctr, size_t len) 58{ 59 int i; 60 61 for (i = len - 1; i >= 0; i--) 62 if (++ctr[i]) /* continue on overflow */ 63 return; 64} 65 66static int 67ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, 68 LIBCRYPTO_EVP_INL_TYPE len) 69{ 70 struct ssh_aes_ctr_ctx *c; 71 size_t n = 0; 72 u_char buf[AES_BLOCK_SIZE]; 73 74 if (len == 0) 75 return (1); 76 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) 77 return (0); 78 79 while ((len--) > 0) { 80 if (n == 0) { 81 AES_encrypt(c->aes_counter, buf, &c->aes_ctx); 82 ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE); 83 } 84 *(dest++) = *(src++) ^ buf[n]; 85 n = (n + 1) % AES_BLOCK_SIZE; 86 } 87 return (1); 88} 89 90static int 91ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv, 92 int enc) 93{ 94 struct ssh_aes_ctr_ctx *c; 95 96 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) { 97 c = xmalloc(sizeof(*c)); 98 EVP_CIPHER_CTX_set_app_data(ctx, c); 99 } 100 if (key != NULL) 101 AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8, 102 &c->aes_ctx); 103 if (iv != NULL) 104 memcpy(c->aes_counter, iv, AES_BLOCK_SIZE); 105 return (1); 106} 107 108static int 109ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx) 110{ 111 struct ssh_aes_ctr_ctx *c; 112 113 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) { 114#ifdef __APPLE_CRYPTO__ 115 AES_destroy_ctx(&c->aes_ctx); 116#endif 117 memset(c, 0, sizeof(*c)); 118 xfree(c); 119 EVP_CIPHER_CTX_set_app_data(ctx, NULL); 120 } 121 return (1); 122} 123 124void 125ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, size_t len) 126{ 127 struct ssh_aes_ctr_ctx *c; 128 129 if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL) 130 fatal("ssh_aes_ctr_iv: no context"); 131 if (doset) 132 memcpy(c->aes_counter, iv, len); 133 else 134 memcpy(iv, c->aes_counter, len); 135} 136 137const EVP_CIPHER * 138evp_aes_128_ctr(void) 139{ 140 static EVP_CIPHER aes_ctr; 141 142 memset(&aes_ctr, 0, sizeof(EVP_CIPHER)); 143 aes_ctr.nid = NID_undef; 144 aes_ctr.block_size = AES_BLOCK_SIZE; 145 aes_ctr.iv_len = AES_BLOCK_SIZE; 146 aes_ctr.key_len = 16; 147 aes_ctr.init = ssh_aes_ctr_init; 148 aes_ctr.cleanup = ssh_aes_ctr_cleanup; 149 aes_ctr.do_cipher = ssh_aes_ctr; 150#ifndef SSH_OLD_EVP 151 aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH | 152 EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV; 153#endif 154 return (&aes_ctr); 155} 156 157#endif /* OPENSSL_HAVE_EVPCTR */ 158