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/*
* crypt.c - blowfish-cbc code
*
* This file is part of the SSH Library
*
* Copyright (c) 2003 by Aris Adamantiadis
*
* The SSH Library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The SSH Library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the SSH Library; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#ifndef _WIN32
#include <netinet/in.h>
#include <arpa/inet.h>
#endif
#ifdef OPENSSL_CRYPTO
#include <openssl/blowfish.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#endif
#include "libssh/priv.h"
#include "libssh/session.h"
#include "libssh/wrapper.h"
#include "libssh/crypto.h"
#include "libssh/buffer.h"
uint32_t packet_decrypt_len(ssh_session session, char *crypted){
uint32_t decrypted;
if (session->current_crypto) {
if (packet_decrypt(session, crypted,
session->current_crypto->in_cipher->blocksize) < 0) {
return 0;
}
}
memcpy(&decrypted,crypted,sizeof(decrypted));
return ntohl(decrypted);
}
int packet_decrypt(ssh_session session, void *data,uint32_t len) {
struct ssh_cipher_struct *crypto = session->current_crypto->in_cipher;
char *out = NULL;
if(len % session->current_crypto->in_cipher->blocksize != 0){
ssh_set_error(session, SSH_FATAL, "Cryptographic functions must be set on at least one blocksize (received %d)",len);
return SSH_ERROR;
}
out = malloc(len);
if (out == NULL) {
return -1;
}
if (crypto->set_decrypt_key(crypto, session->current_crypto->decryptkey,
session->current_crypto->decryptIV) < 0) {
SAFE_FREE(out);
return -1;
}
crypto->cbc_decrypt(crypto,data,out,len);
memcpy(data,out,len);
memset(out,0,len);
SAFE_FREE(out);
return 0;
}
unsigned char *packet_encrypt(ssh_session session, void *data, uint32_t len) {
struct ssh_cipher_struct *crypto = NULL;
HMACCTX ctx = NULL;
char *out = NULL;
unsigned int finallen;
uint32_t seq;
if (!session->current_crypto) {
return NULL; /* nothing to do here */
}
if(len % session->current_crypto->in_cipher->blocksize != 0){
ssh_set_error(session, SSH_FATAL, "Cryptographic functions must be set on at least one blocksize (received %d)",len);
return NULL;
}
out = malloc(len);
if (out == NULL) {
return NULL;
}
seq = ntohl(session->send_seq);
crypto = session->current_crypto->out_cipher;
if (crypto->set_encrypt_key(crypto, session->current_crypto->encryptkey,
session->current_crypto->encryptIV) < 0) {
SAFE_FREE(out);
return NULL;
}
if (session->version == 2) {
ctx = hmac_init(session->current_crypto->encryptMAC,20,SSH_HMAC_SHA1);
if (ctx == NULL) {
SAFE_FREE(out);
return NULL;
}
hmac_update(ctx,(unsigned char *)&seq,sizeof(uint32_t));
hmac_update(ctx,data,len);
hmac_final(ctx,session->current_crypto->hmacbuf,&finallen);
#ifdef DEBUG_CRYPTO
ssh_print_hexa("mac: ",data,len);
if (finallen != 20) {
printf("Final len is %d\n",finallen);
}
ssh_print_hexa("Packet hmac", session->current_crypto->hmacbuf, 20);
#endif
}
crypto->cbc_encrypt(crypto, data, out, len);
memcpy(data, out, len);
memset(out, 0, len);
SAFE_FREE(out);
if (session->version == 2) {
return session->current_crypto->hmacbuf;
}
return NULL;
}
/**
* @internal
*
* @brief Verify the hmac of a packet
*
* @param session The session to use.
* @param buffer The buffer to verify the hmac from.
* @param mac The mac to compare with the hmac.
*
* @return 0 if hmac and mac are equal, < 0 if not or an error
* occurred.
*/
int packet_hmac_verify(ssh_session session, ssh_buffer buffer,
unsigned char *mac) {
unsigned char hmacbuf[EVP_MAX_MD_SIZE] = {0};
HMACCTX ctx;
unsigned int len;
uint32_t seq;
ctx = hmac_init(session->current_crypto->decryptMAC, 20, SSH_HMAC_SHA1);
if (ctx == NULL) {
return -1;
}
seq = htonl(session->recv_seq);
hmac_update(ctx, (unsigned char *) &seq, sizeof(uint32_t));
hmac_update(ctx, buffer_get_rest(buffer), buffer_get_rest_len(buffer));
hmac_final(ctx, hmacbuf, &len);
#ifdef DEBUG_CRYPTO
ssh_print_hexa("received mac",mac,len);
ssh_print_hexa("Computed mac",hmacbuf,len);
ssh_print_hexa("seq",(unsigned char *)&seq,sizeof(uint32_t));
#endif
if (memcmp(mac, hmacbuf, len) == 0) {
return 0;
}
return -1;
}
/* vim: set ts=2 sw=2 et cindent: */
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