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121 lines
3.4 KiB
121 lines
3.4 KiB
/*
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* Dropbear SSH
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*
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* Copyright (c) 2002,2003 Matt Johnston
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* Copyright (c) 2020 by Vladislav Grishenko
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE. */
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#include "includes.h"
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#include "algo.h"
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#include "dbutil.h"
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#include "gcm.h"
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#if DROPBEAR_ENABLE_GCM_MODE
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#define GHASH_LEN 16
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static const struct dropbear_hash dropbear_ghash =
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{NULL, 0, GHASH_LEN};
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static int dropbear_gcm_start(int cipher, const unsigned char *IV,
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const unsigned char *key, int keylen,
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int UNUSED(num_rounds), dropbear_gcm_state *state) {
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int err;
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TRACE2(("enter dropbear_gcm_start"))
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if ((err = gcm_init(&state->gcm, cipher, key, keylen)) != CRYPT_OK) {
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return err;
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}
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memcpy(state->iv, IV, GCM_NONCE_LEN);
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TRACE2(("leave dropbear_gcm_start"))
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return CRYPT_OK;
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}
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static int dropbear_gcm_crypt(unsigned int UNUSED(seq),
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const unsigned char *in, unsigned char *out,
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unsigned long len, unsigned long taglen,
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dropbear_gcm_state *state, int direction) {
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unsigned char *iv, tag[GHASH_LEN];
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int i, err;
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TRACE2(("enter dropbear_gcm_crypt"))
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if (len < 4 || taglen != GHASH_LEN) {
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return CRYPT_ERROR;
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}
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gcm_reset(&state->gcm);
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if ((err = gcm_add_iv(&state->gcm,
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state->iv, GCM_NONCE_LEN)) != CRYPT_OK) {
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return err;
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}
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if ((err = gcm_add_aad(&state->gcm, in, 4)) != CRYPT_OK) {
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return err;
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}
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if ((err = gcm_process(&state->gcm, (unsigned char *) in + 4,
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len - 4, out + 4, direction)) != CRYPT_OK) {
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return err;
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}
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if (direction == LTC_ENCRYPT) {
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gcm_done(&state->gcm, out + len, &taglen);
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} else {
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gcm_done(&state->gcm, tag, &taglen);
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if (constant_time_memcmp(in + len, tag, taglen) != 0) {
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return CRYPT_ERROR;
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}
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}
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/* increment invocation counter */
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iv = state->iv + GCM_IVFIX_LEN;
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for (i = GCM_IVCTR_LEN - 1; i >= 0 && ++iv[i] == 0; i--);
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TRACE2(("leave dropbear_gcm_crypt"))
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return CRYPT_OK;
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}
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static int dropbear_gcm_getlength(unsigned int UNUSED(seq),
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const unsigned char *in, unsigned int *outlen,
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unsigned long len, dropbear_gcm_state* UNUSED(state)) {
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TRACE2(("enter dropbear_gcm_getlength"))
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if (len < 4) {
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return CRYPT_ERROR;
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}
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LOAD32H(*outlen, in);
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TRACE2(("leave dropbear_gcm_getlength"))
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return CRYPT_OK;
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}
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const struct dropbear_cipher_mode dropbear_mode_gcm =
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{(void *)dropbear_gcm_start, NULL, NULL,
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(void *)dropbear_gcm_crypt,
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(void *)dropbear_gcm_getlength, &dropbear_ghash};
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#endif /* DROPBEAR_ENABLE_GCM_MODE */
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