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/*
* Dropbear SSH
*
* Copyright (c) 2002,2003 Matt Johnston
* Copyright (c) 2020 by Vladislav Grishenko
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE. */
#include "includes.h"
#include "algo.h"
#include "dbutil.h"
#include "chachapoly.h"
#if DROPBEAR_CHACHA20POLY1305
#define CHACHA20_KEY_LEN 32
#define CHACHA20_BLOCKSIZE 8
#define POLY1305_KEY_LEN 32
#define POLY1305_TAG_LEN 16
static const struct ltc_cipher_descriptor dummy = {.name = NULL};
static const struct dropbear_hash dropbear_chachapoly_mac =
{NULL, POLY1305_KEY_LEN, POLY1305_TAG_LEN};
const struct dropbear_cipher dropbear_chachapoly =
{&dummy, CHACHA20_KEY_LEN*2, CHACHA20_BLOCKSIZE};
static int dropbear_chachapoly_start(int UNUSED(cipher), const unsigned char* UNUSED(IV),
const unsigned char *key, int keylen,
int UNUSED(num_rounds), dropbear_chachapoly_state *state) {
int err;
TRACE2(("enter dropbear_chachapoly_start"))
if (keylen != CHACHA20_KEY_LEN*2) {
return CRYPT_ERROR;
}
if ((err = chacha_setup(&state->chacha, key,
CHACHA20_KEY_LEN, 20)) != CRYPT_OK) {
return err;
}
if ((err = chacha_setup(&state->header, key + CHACHA20_KEY_LEN,
CHACHA20_KEY_LEN, 20) != CRYPT_OK)) {
return err;
}
TRACE2(("leave dropbear_chachapoly_start"))
return CRYPT_OK;
}
static int dropbear_chachapoly_crypt(unsigned int seq,
const unsigned char *in, unsigned char *out,
unsigned long len, unsigned long taglen,
dropbear_chachapoly_state *state, int direction) {
poly1305_state poly;
unsigned char seqbuf[8], key[POLY1305_KEY_LEN], tag[POLY1305_TAG_LEN];
int err;
TRACE2(("enter dropbear_chachapoly_crypt"))
if (len < 4 || taglen != POLY1305_TAG_LEN) {
return CRYPT_ERROR;
}
STORE64H((uint64_t)seq, seqbuf);
chacha_ivctr64(&state->chacha, seqbuf, sizeof(seqbuf), 0);
if ((err = chacha_keystream(&state->chacha, key, sizeof(key))) != CRYPT_OK) {
return err;
}
poly1305_init(&poly, key, sizeof(key));
if (direction == LTC_DECRYPT) {
poly1305_process(&poly, in, len);
poly1305_done(&poly, tag, &taglen);
if (constant_time_memcmp(in + len, tag, taglen) != 0) {
return CRYPT_ERROR;
}
}
chacha_ivctr64(&state->header, seqbuf, sizeof(seqbuf), 0);
if ((err = chacha_crypt(&state->header, in, 4, out)) != CRYPT_OK) {
return err;
}
chacha_ivctr64(&state->chacha, seqbuf, sizeof(seqbuf), 1);
if ((err = chacha_crypt(&state->chacha, in + 4, len - 4, out + 4)) != CRYPT_OK) {
return err;
}
if (direction == LTC_ENCRYPT) {
poly1305_process(&poly, out, len);
poly1305_done(&poly, out + len, &taglen);
}
TRACE2(("leave dropbear_chachapoly_crypt"))
return CRYPT_OK;
}
static int dropbear_chachapoly_getlength(unsigned int seq,
const unsigned char *in, unsigned int *outlen,
unsigned long len, dropbear_chachapoly_state *state) {
unsigned char seqbuf[8], buf[4];
int err;
TRACE2(("enter dropbear_chachapoly_getlength"))
if (len < sizeof(buf)) {
return CRYPT_ERROR;
}
STORE64H((uint64_t)seq, seqbuf);
chacha_ivctr64(&state->header, seqbuf, sizeof(seqbuf), 0);
if ((err = chacha_crypt(&state->header, in, sizeof(buf), buf)) != CRYPT_OK) {
return err;
}
LOAD32H(*outlen, buf);
TRACE2(("leave dropbear_chachapoly_getlength"))
return CRYPT_OK;
}
const struct dropbear_cipher_mode dropbear_mode_chachapoly =
{(void *)dropbear_chachapoly_start, NULL, NULL,
(void *)dropbear_chachapoly_crypt,
(void *)dropbear_chachapoly_getlength, &dropbear_chachapoly_mac};
#endif /* DROPBEAR_CHACHA20POLY1305 */
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