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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 "gcm.h"
#if DROPBEAR_ENABLE_GCM_MODE
#define GHASH_LEN 16
static const struct dropbear_hash dropbear_ghash =
{NULL, 0, GHASH_LEN};
static int dropbear_gcm_start(int cipher, const unsigned char *IV,
const unsigned char *key, int keylen,
int UNUSED(num_rounds), dropbear_gcm_state *state) {
int err;
TRACE2(("enter dropbear_gcm_start"))
if ((err = gcm_init(&state->gcm, cipher, key, keylen)) != CRYPT_OK) {
return err;
}
memcpy(state->iv, IV, GCM_NONCE_LEN);
TRACE2(("leave dropbear_gcm_start"))
return CRYPT_OK;
}
static int dropbear_gcm_crypt(unsigned int UNUSED(seq),
const unsigned char *in, unsigned char *out,
unsigned long len, unsigned long taglen,
dropbear_gcm_state *state, int direction) {
unsigned char *iv, tag[GHASH_LEN];
int i, err;
TRACE2(("enter dropbear_gcm_crypt"))
if (len < 4 || taglen != GHASH_LEN) {
return CRYPT_ERROR;
}
gcm_reset(&state->gcm);
if ((err = gcm_add_iv(&state->gcm,
state->iv, GCM_NONCE_LEN)) != CRYPT_OK) {
return err;
}
if ((err = gcm_add_aad(&state->gcm, in, 4)) != CRYPT_OK) {
return err;
}
if ((err = gcm_process(&state->gcm, (unsigned char *) in + 4,
len - 4, out + 4, direction)) != CRYPT_OK) {
return err;
}
if (direction == LTC_ENCRYPT) {
gcm_done(&state->gcm, out + len, &taglen);
} else {
gcm_done(&state->gcm, tag, &taglen);
if (constant_time_memcmp(in + len, tag, taglen) != 0) {
return CRYPT_ERROR;
}
}
/* increment invocation counter */
iv = state->iv + GCM_IVFIX_LEN;
for (i = GCM_IVCTR_LEN - 1; i >= 0 && ++iv[i] == 0; i--);
TRACE2(("leave dropbear_gcm_crypt"))
return CRYPT_OK;
}
static int dropbear_gcm_getlength(unsigned int UNUSED(seq),
const unsigned char *in, unsigned int *outlen,
unsigned long len, dropbear_gcm_state* UNUSED(state)) {
TRACE2(("enter dropbear_gcm_parse"))
if (len < 4) {
return CRYPT_ERROR;
}
LOAD32H(*outlen, in);
TRACE2(("leave dropbear_gcm_parse"))
return CRYPT_OK;
}
const struct dropbear_cipher_mode dropbear_mode_gcm =
{(void *)dropbear_gcm_start, NULL, NULL,
(void *)dropbear_gcm_crypt,
(void *)dropbear_gcm_getlength, &dropbear_ghash};
#endif /* DROPBEAR_ENABLE_GCM_MODE */
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