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d4af9e693f
I have worked hard to reduce diffs against the vendor branch. One notable change in that respect is that we no longer prefer DSA over RSA - the reasons for doing so went away years ago. This may cause some surprises, as ssh will warn about unknown host keys even for hosts whose keys haven't changed. MFC after: 6 weeks
147 lines
3.5 KiB
C
147 lines
3.5 KiB
C
/* $OpenBSD: cipher-ctr.c,v 1.10 2006/08/03 03:34:42 deraadt 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 *, u_int);
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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, u_int 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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u_int len)
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{
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struct ssh_aes_ctr_ctx *c;
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u_int 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, u_int 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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