1 /* 2 * Copyright (c) 2003 Markus Friedl <markus@openbsd.org> 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 /* 17 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 18 * Use is subject to license terms. 19 */ 20 #include "includes.h" 21 RCSID("$OpenBSD: cipher-ctr.c,v 1.4 2004/02/06 23:41:13 dtucker Exp $"); 22 23 #pragma ident "%Z%%M% %I% %E% SMI" 24 25 #include <openssl/evp.h> 26 27 #include "log.h" 28 #include "xmalloc.h" 29 30 #if OPENSSL_VERSION_NUMBER < 0x00906000L 31 #define SSH_OLD_EVP 32 #endif 33 34 #if (OPENSSL_VERSION_NUMBER < 0x00907000L) 35 #include "rijndael.h" 36 #define AES_KEY rijndael_ctx 37 #define AES_BLOCK_SIZE 16 38 #define AES_encrypt(a, b, c) rijndael_encrypt(c, a, b) 39 #define AES_set_encrypt_key(a, b, c) rijndael_set_key(c, (u_char *)a, b, 1) 40 #else 41 #include <openssl/aes.h> 42 #endif 43 44 const EVP_CIPHER *evp_aes_128_ctr(void); 45 void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); 46 47 struct ssh_aes_ctr_ctx 48 { 49 AES_KEY aes_ctx; 50 u_char aes_counter[AES_BLOCK_SIZE]; 51 }; 52 53 /* 54 * increment counter 'ctr', 55 * the counter is of size 'len' bytes and stored in network-byte-order. 56 * (LSB at ctr[len-1], MSB at ctr[0]) 57 */ 58 static void 59 ssh_ctr_inc(u_char *ctr, u_int len) 60 { 61 int i; 62 63 for (i = len - 1; i >= 0; i--) 64 if (++ctr[i]) /* continue on overflow */ 65 return; 66 } 67 68 static int 69 ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src, 70 u_int len) 71 { 72 struct ssh_aes_ctr_ctx *c; 73 u_int n = 0; 74 u_char buf[AES_BLOCK_SIZE]; 75 76 if (len == 0) 77 return (1); 78 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) 79 return (0); 80 81 while ((len--) > 0) { 82 if (n == 0) { 83 AES_encrypt(c->aes_counter, buf, &c->aes_ctx); 84 ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE); 85 } 86 *(dest++) = *(src++) ^ buf[n]; 87 n = (n + 1) % AES_BLOCK_SIZE; 88 } 89 return (1); 90 } 91 92 static int 93 ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv, 94 int enc) 95 { 96 struct ssh_aes_ctr_ctx *c; 97 98 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) { 99 c = xmalloc(sizeof(*c)); 100 EVP_CIPHER_CTX_set_app_data(ctx, c); 101 } 102 if (key != NULL) 103 AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8, 104 &c->aes_ctx); 105 if (iv != NULL) 106 memcpy(c->aes_counter, iv, AES_BLOCK_SIZE); 107 return (1); 108 } 109 110 static int 111 ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx) 112 { 113 struct ssh_aes_ctr_ctx *c; 114 115 if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) { 116 memset(c, 0, sizeof(*c)); 117 xfree(c); 118 EVP_CIPHER_CTX_set_app_data(ctx, NULL); 119 } 120 return (1); 121 } 122 123 void 124 ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, u_int len) 125 { 126 struct ssh_aes_ctr_ctx *c; 127 128 if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL) 129 fatal("ssh_aes_ctr_iv: no context"); 130 if (doset) 131 memcpy(c->aes_counter, iv, len); 132 else 133 memcpy(iv, c->aes_counter, len); 134 } 135 136 const EVP_CIPHER * 137 evp_aes_128_ctr(void) 138 { 139 static EVP_CIPHER aes_ctr; 140 141 memset(&aes_ctr, 0, sizeof(EVP_CIPHER)); 142 aes_ctr.nid = NID_undef; 143 aes_ctr.block_size = AES_BLOCK_SIZE; 144 aes_ctr.iv_len = AES_BLOCK_SIZE; 145 aes_ctr.key_len = 16; 146 aes_ctr.init = ssh_aes_ctr_init; 147 aes_ctr.cleanup = ssh_aes_ctr_cleanup; 148 aes_ctr.do_cipher = ssh_aes_ctr; 149 #ifndef SSH_OLD_EVP 150 aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH | 151 EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV; 152 #endif 153 return (&aes_ctr); 154 } 155