147 lines
3.6 KiB
C
147 lines
3.6 KiB
C
/* $OpenBSD: cipher-ctr.c,v 1.11 2010/10/01 23:05:32 djm Exp $ */
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/*
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* Copyright (c) 2003 Markus Friedl <markus@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <stdarg.h>
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#include <string.h>
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#include <openssl/evp.h>
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#include "xmalloc.h"
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#include "log.h"
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/* compatibility with old or broken OpenSSL versions */
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#include "openbsd-compat/openssl-compat.h"
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#ifndef USE_BUILTIN_RIJNDAEL
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#include <openssl/aes.h>
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#endif
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const EVP_CIPHER *evp_aes_128_ctr(void);
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void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, size_t);
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struct ssh_aes_ctr_ctx
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{
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AES_KEY aes_ctx;
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u_char aes_counter[AES_BLOCK_SIZE];
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};
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/*
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* increment counter 'ctr',
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* the counter is of size 'len' bytes and stored in network-byte-order.
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* (LSB at ctr[len-1], MSB at ctr[0])
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*/
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static void
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ssh_ctr_inc(u_char *ctr, size_t len)
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{
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int i;
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for (i = len - 1; i >= 0; i--)
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if (++ctr[i]) /* continue on overflow */
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return;
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}
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static int
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ssh_aes_ctr(EVP_CIPHER_CTX *ctx, u_char *dest, const u_char *src,
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LIBCRYPTO_EVP_INL_TYPE len)
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{
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struct ssh_aes_ctr_ctx *c;
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size_t n = 0;
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u_char buf[AES_BLOCK_SIZE];
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if (len == 0)
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return (1);
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if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL)
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return (0);
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while ((len--) > 0) {
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if (n == 0) {
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AES_encrypt(c->aes_counter, buf, &c->aes_ctx);
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ssh_ctr_inc(c->aes_counter, AES_BLOCK_SIZE);
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}
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*(dest++) = *(src++) ^ buf[n];
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n = (n + 1) % AES_BLOCK_SIZE;
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}
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return (1);
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}
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static int
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ssh_aes_ctr_init(EVP_CIPHER_CTX *ctx, const u_char *key, const u_char *iv,
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int enc)
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{
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struct ssh_aes_ctr_ctx *c;
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if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) == NULL) {
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c = xmalloc(sizeof(*c));
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EVP_CIPHER_CTX_set_app_data(ctx, c);
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}
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if (key != NULL)
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AES_set_encrypt_key(key, EVP_CIPHER_CTX_key_length(ctx) * 8,
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&c->aes_ctx);
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if (iv != NULL)
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memcpy(c->aes_counter, iv, AES_BLOCK_SIZE);
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return (1);
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}
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static int
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ssh_aes_ctr_cleanup(EVP_CIPHER_CTX *ctx)
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{
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struct ssh_aes_ctr_ctx *c;
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if ((c = EVP_CIPHER_CTX_get_app_data(ctx)) != NULL) {
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memset(c, 0, sizeof(*c));
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xfree(c);
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EVP_CIPHER_CTX_set_app_data(ctx, NULL);
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}
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return (1);
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}
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void
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ssh_aes_ctr_iv(EVP_CIPHER_CTX *evp, int doset, u_char * iv, size_t len)
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{
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struct ssh_aes_ctr_ctx *c;
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if ((c = EVP_CIPHER_CTX_get_app_data(evp)) == NULL)
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fatal("ssh_aes_ctr_iv: no context");
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if (doset)
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memcpy(c->aes_counter, iv, len);
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else
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memcpy(iv, c->aes_counter, len);
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}
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const EVP_CIPHER *
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evp_aes_128_ctr(void)
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{
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static EVP_CIPHER aes_ctr;
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memset(&aes_ctr, 0, sizeof(EVP_CIPHER));
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aes_ctr.nid = NID_undef;
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aes_ctr.block_size = AES_BLOCK_SIZE;
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aes_ctr.iv_len = AES_BLOCK_SIZE;
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aes_ctr.key_len = 16;
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aes_ctr.init = ssh_aes_ctr_init;
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aes_ctr.cleanup = ssh_aes_ctr_cleanup;
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aes_ctr.do_cipher = ssh_aes_ctr;
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#ifndef SSH_OLD_EVP
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aes_ctr.flags = EVP_CIPH_CBC_MODE | EVP_CIPH_VARIABLE_LENGTH |
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EVP_CIPH_ALWAYS_CALL_INIT | EVP_CIPH_CUSTOM_IV;
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#endif
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return (&aes_ctr);
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}
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