ports/libssh
ports/libssh
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libssh/src/dh.c
Aris Adamantiadis 63c3f0e736 Implement key re-exchange
2012-12-23 23:09:50 +01:00

1137 строки
30 KiB
C
Исходник Ответственный История

/*
* dh.c - Diffie-Helman algorithm code against SSH 2
*
* This file is part of the SSH Library
*
* Copyright (c) 2003-2008 by Aris Adamantiadis
* Copyright (c) 2009 by Andreas Schneider <mail@cynapses.org>
* Copyright (c) 2012 by Dmitriy Kuznetsov <dk@yandex.ru>
*
* 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.
*/
/*
* Let us resume the dh protocol.
* Each side computes a private prime number, x at client side, y at server
* side.
* g and n are two numbers common to every ssh software.
* client's public key (e) is calculated by doing:
* e = g^x mod p
* client sends e to the server.
* the server computes his own public key, f
* f = g^y mod p
* it sends it to the client
* the common key K is calculated by the client by doing
* k = f^x mod p
* the server does the same with the client public key e
* k' = e^y mod p
* if everything went correctly, k and k' are equal
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#ifndef _WIN32
#include <netinet/in.h>
#include <arpa/inet.h>
#endif
#include "libssh/priv.h"
#include "libssh/crypto.h"
#include "libssh/buffer.h"
#include "libssh/session.h"
#include "libssh/misc.h"
#include "libssh/dh.h"
#include "libssh/ssh2.h"
#include "libssh/pki.h"
/* todo: remove it */
#include "libssh/string.h"
#ifdef HAVE_LIBCRYPTO
#include <openssl/rand.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#endif
static unsigned char p_group1_value[] = {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
#define P_GROUP1_LEN 128 /* Size in bytes of the p number */
static unsigned char p_group14_value[] = {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF};
#define P_GROUP14_LEN 256 /* Size in bytes of the p number for group 14 */
static unsigned long g_int = 2 ; /* G is defined as 2 by the ssh2 standards */
static bignum g;
static bignum p_group1;
static bignum p_group14;
static int ssh_crypto_initialized;
static bignum select_p(enum ssh_key_exchange_e type) {
return type == SSH_KEX_DH_GROUP14_SHA1 ? p_group14 : p_group1;
}
int ssh_get_random(void *where, int len, int strong){
#ifdef HAVE_LIBGCRYPT
/* variable not used in gcrypt */
(void) strong;
/* not using GCRY_VERY_STRONG_RANDOM which is a bit overkill */
gcry_randomize(where,len,GCRY_STRONG_RANDOM);
return 1;
#elif defined HAVE_LIBCRYPTO
if (strong) {
return RAND_bytes(where,len);
} else {
return RAND_pseudo_bytes(where,len);
}
#endif
/* never reached */
return 1;
}
/*
* This inits the values g and p which are used for DH key agreement
* FIXME: Make the function thread safe by adding a semaphore or mutex.
*/
int ssh_crypto_init(void) {
if (ssh_crypto_initialized == 0) {
#ifdef HAVE_LIBGCRYPT
gcry_check_version(NULL);
if (!gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P,0)) {
gcry_control(GCRYCTL_INIT_SECMEM, 4096);
gcry_control(GCRYCTL_INITIALIZATION_FINISHED,0);
}
#endif
g = bignum_new();
if (g == NULL) {
return -1;
}
bignum_set_word(g,g_int);
#ifdef HAVE_LIBGCRYPT
bignum_bin2bn(p_group1_value, P_GROUP1_LEN, &p_group1);
if (p_group1 == NULL) {
bignum_free(g);
g = NULL;
return -1;
}
bignum_bin2bn(p_group14_value, P_GROUP14_LEN, &p_group14);
if (p_group1 == NULL) {
bignum_free(g);
bignum_free(p_group1);
g = NULL;
p_group1 = NULL;
return -1;
}
#elif defined HAVE_LIBCRYPTO
p_group1 = bignum_new();
if (p_group1 == NULL) {
bignum_free(g);
g = NULL;
return -1;
}
bignum_bin2bn(p_group1_value, P_GROUP1_LEN, p_group1);
p_group14 = bignum_new();
if (p_group14 == NULL) {
bignum_free(g);
bignum_free(p_group1);
g = NULL;
p_group1 = NULL;
return -1;
}
bignum_bin2bn(p_group14_value, P_GROUP14_LEN, p_group14);
OpenSSL_add_all_algorithms();
#endif
ssh_crypto_initialized = 1;
}
return 0;
}
void ssh_crypto_finalize(void) {
if (ssh_crypto_initialized) {
bignum_free(g);
g = NULL;
bignum_free(p_group1);
p_group1 = NULL;
bignum_free(p_group14);
p_group14 = NULL;
#ifdef HAVE_LIBGCRYPT
gcry_control(GCRYCTL_TERM_SECMEM);
#elif defined HAVE_LIBCRYPTO
EVP_cleanup();
CRYPTO_cleanup_all_ex_data();
#endif
ssh_crypto_initialized=0;
}
}
/* prints the bignum on stderr */
void ssh_print_bignum(const char *which, bignum num) {
#ifdef HAVE_LIBGCRYPT
unsigned char *hex = NULL;
bignum_bn2hex(num, &hex);
#elif defined HAVE_LIBCRYPTO
char *hex = NULL;
hex = bignum_bn2hex(num);
#endif
fprintf(stderr, "%s value: ", which);
fprintf(stderr, "%s\n", (hex == NULL) ? "(null)" : (char *) hex);
SAFE_FREE(hex);
}
/**
* @brief Convert a buffer into a colon separated hex string.
* The caller has to free the memory.
*
* @param what What should be converted to a hex string.
*
* @param len Length of the buffer to convert.
*
* @return The hex string or NULL on error.
*
* @see ssh_string_free_char()
*/
char *ssh_get_hexa(const unsigned char *what, size_t len) {
const char h[] = "0123456789abcdef";
char *hexa;
size_t i;
size_t hlen = len * 3;
if (len > (UINT_MAX - 1) / 3) {
return NULL;
}
hexa = malloc(hlen + 1);
if (hexa == NULL) {
return NULL;
}
for (i = 0; i < len; i++) {
hexa[i * 3] = h[(what[i] >> 4) & 0xF];
hexa[i * 3 + 1] = h[what[i] & 0xF];
hexa[i * 3 + 2] = ':';
}
hexa[hlen - 1] = '\0';
return hexa;
}
/**
* @brief Print a buffer as colon separated hex string.
*
* @param descr Description printed in front of the hex string.
*
* @param what What should be converted to a hex string.
*
* @param len Length of the buffer to convert.
*/
void ssh_print_hexa(const char *descr, const unsigned char *what, size_t len) {
char *hexa = ssh_get_hexa(what, len);
if (hexa == NULL) {
return;
}
printf("%s: %s\n", descr, hexa);
free(hexa);
}
int dh_generate_x(ssh_session session) {
session->next_crypto->x = bignum_new();
if (session->next_crypto->x == NULL) {
return -1;
}
#ifdef HAVE_LIBGCRYPT
bignum_rand(session->next_crypto->x, 128);
#elif defined HAVE_LIBCRYPTO
bignum_rand(session->next_crypto->x, 128, 0, -1);
#endif
/* not harder than this */
#ifdef DEBUG_CRYPTO
ssh_print_bignum("x", session->next_crypto->x);
#endif
return 0;
}
/* used by server */
int dh_generate_y(ssh_session session) {
session->next_crypto->y = bignum_new();
if (session->next_crypto->y == NULL) {
return -1;
}
#ifdef HAVE_LIBGCRYPT
bignum_rand(session->next_crypto->y, 128);
#elif defined HAVE_LIBCRYPTO
bignum_rand(session->next_crypto->y, 128, 0, -1);
#endif
/* not harder than this */
#ifdef DEBUG_CRYPTO
ssh_print_bignum("y", session->next_crypto->y);
#endif
return 0;
}
/* used by server */
int dh_generate_e(ssh_session session) {
#ifdef HAVE_LIBCRYPTO
bignum_CTX ctx = bignum_ctx_new();
if (ctx == NULL) {
return -1;
}
#endif
session->next_crypto->e = bignum_new();
if (session->next_crypto->e == NULL) {
#ifdef HAVE_LIBCRYPTO
bignum_ctx_free(ctx);
#endif
return -1;
}
#ifdef HAVE_LIBGCRYPT
bignum_mod_exp(session->next_crypto->e, g, session->next_crypto->x,
select_p(session->next_crypto->kex_type));
#elif defined HAVE_LIBCRYPTO
bignum_mod_exp(session->next_crypto->e, g, session->next_crypto->x,
select_p(session->next_crypto->kex_type), ctx);
#endif
#ifdef DEBUG_CRYPTO
ssh_print_bignum("e", session->next_crypto->e);
#endif
#ifdef HAVE_LIBCRYPTO
bignum_ctx_free(ctx);
#endif
return 0;
}
int dh_generate_f(ssh_session session) {
#ifdef HAVE_LIBCRYPTO
bignum_CTX ctx = bignum_ctx_new();
if (ctx == NULL) {
return -1;
}
#endif
session->next_crypto->f = bignum_new();
if (session->next_crypto->f == NULL) {
#ifdef HAVE_LIBCRYPTO
bignum_ctx_free(ctx);
#endif
return -1;
}
#ifdef HAVE_LIBGCRYPT
bignum_mod_exp(session->next_crypto->f, g, session->next_crypto->y,
select_p(session->next_crypto->kex_type));
#elif defined HAVE_LIBCRYPTO
bignum_mod_exp(session->next_crypto->f, g, session->next_crypto->y,
select_p(session->next_crypto->kex_type), ctx);
#endif
#ifdef DEBUG_CRYPTO
ssh_print_bignum("f", session->next_crypto->f);
#endif
#ifdef HAVE_LIBCRYPTO
bignum_ctx_free(ctx);
#endif
return 0;
}
ssh_string make_bignum_string(bignum num) {
ssh_string ptr = NULL;
int pad = 0;
unsigned int len = bignum_num_bytes(num);
unsigned int bits = bignum_num_bits(num);
if (len == 0) {
return NULL;
}
/* If the first bit is set we have a negative number */
if (!(bits % 8) && bignum_is_bit_set(num, bits - 1)) {
pad++;
}
#ifdef DEBUG_CRYPTO
fprintf(stderr, "%d bits, %d bytes, %d padding\n", bits, len, pad);
#endif /* DEBUG_CRYPTO */
ptr = ssh_string_new(len + pad);
if (ptr == NULL) {
return NULL;
}
/* We have a negative number so we need a leading zero */
if (pad) {
ptr->data[0] = 0;
}
#ifdef HAVE_LIBGCRYPT
bignum_bn2bin(num, len, ptr->data + pad);
#elif HAVE_LIBCRYPTO
bignum_bn2bin(num, ptr->data + pad);
#endif
return ptr;
}
bignum make_string_bn(ssh_string string){
bignum bn = NULL;
unsigned int len = ssh_string_len(string);
#ifdef DEBUG_CRYPTO
fprintf(stderr, "Importing a %d bits, %d bytes object ...\n",
len * 8, len);
#endif /* DEBUG_CRYPTO */
#ifdef HAVE_LIBGCRYPT
bignum_bin2bn(string->data, len, &bn);
#elif defined HAVE_LIBCRYPTO
bn = bignum_bin2bn(string->data, len, NULL);
#endif
return bn;
}
ssh_string dh_get_e(ssh_session session) {
return make_bignum_string(session->next_crypto->e);
}
/* used by server */
ssh_string dh_get_f(ssh_session session) {
return make_bignum_string(session->next_crypto->f);
}
void dh_import_pubkey(ssh_session session, ssh_string pubkey_string) {
session->next_crypto->server_pubkey = pubkey_string;
}
int dh_import_f(ssh_session session, ssh_string f_string) {
session->next_crypto->f = make_string_bn(f_string);
if (session->next_crypto->f == NULL) {
return -1;
}
#ifdef DEBUG_CRYPTO
ssh_print_bignum("f",session->next_crypto->f);
#endif
return 0;
}
/* used by the server implementation */
int dh_import_e(ssh_session session, ssh_string e_string) {
session->next_crypto->e = make_string_bn(e_string);
if (session->next_crypto->e == NULL) {
return -1;
}
#ifdef DEBUG_CRYPTO
ssh_print_bignum("e",session->next_crypto->e);
#endif
return 0;
}
int dh_build_k(ssh_session session) {
#ifdef HAVE_LIBCRYPTO
bignum_CTX ctx = bignum_ctx_new();
if (ctx == NULL) {
return -1;
}
#endif
session->next_crypto->k = bignum_new();
if (session->next_crypto->k == NULL) {
#ifdef HAVE_LIBCRYPTO
bignum_ctx_free(ctx);
#endif
return -1;
}
/* the server and clients don't use the same numbers */
#ifdef HAVE_LIBGCRYPT
if(session->client) {
bignum_mod_exp(session->next_crypto->k, session->next_crypto->f,
session->next_crypto->x, select_p(session->next_crypto->kex_type));
} else {
bignum_mod_exp(session->next_crypto->k, session->next_crypto->e,
session->next_crypto->y, select_p(session->next_crypto->kex_type));
}
#elif defined HAVE_LIBCRYPTO
if (session->client) {
bignum_mod_exp(session->next_crypto->k, session->next_crypto->f,
session->next_crypto->x, select_p(session->next_crypto->kex_type), ctx);
} else {
bignum_mod_exp(session->next_crypto->k, session->next_crypto->e,
session->next_crypto->y, select_p(session->next_crypto->kex_type), ctx);
}
#endif
#ifdef DEBUG_CRYPTO
ssh_print_hexa("Session server cookie",
session->next_crypto->server_kex.cookie, 16);
ssh_print_hexa("Session client cookie",
session->next_crypto->client_kex.cookie, 16);
ssh_print_bignum("Shared secret key", session->next_crypto->k);
#endif
#ifdef HAVE_LIBCRYPTO
bignum_ctx_free(ctx);
#endif
return 0;
}
/** @internal
* @brief Starts diffie-hellman-group1 key exchange
*/
int ssh_client_dh_init(ssh_session session){
ssh_string e = NULL;
int rc;
enter_function();
if (buffer_add_u8(session->out_buffer, SSH2_MSG_KEXDH_INIT) < 0) {
goto error;
}
if (dh_generate_x(session) < 0) {
goto error;
}
if (dh_generate_e(session) < 0) {
goto error;
}
e = dh_get_e(session);
if (e == NULL) {
goto error;
}
if (buffer_add_ssh_string(session->out_buffer, e) < 0) {
goto error;
}
ssh_string_burn(e);
ssh_string_free(e);
e=NULL;
rc = packet_send(session);
return rc;
error:
if(e != NULL){
ssh_string_burn(e);
ssh_string_free(e);
}
leave_function();
return SSH_ERROR;
}
int ssh_client_dh_reply(ssh_session session, ssh_buffer packet){
ssh_string f;
ssh_string pubkey = NULL;
ssh_string signature = NULL;
int rc;
pubkey = buffer_get_ssh_string(packet);
if (pubkey == NULL){
ssh_set_error(session,SSH_FATAL, "No public key in packet");
goto error;
}
dh_import_pubkey(session, pubkey);
f = buffer_get_ssh_string(packet);
if (f == NULL) {
ssh_set_error(session,SSH_FATAL, "No F number in packet");
goto error;
}
rc = dh_import_f(session, f);
ssh_string_burn(f);
ssh_string_free(f);
if (rc < 0) {
ssh_set_error(session, SSH_FATAL, "Cannot import f number");
goto error;
}
signature = buffer_get_ssh_string(packet);
if (signature == NULL) {
ssh_set_error(session, SSH_FATAL, "No signature in packet");
goto error;
}
session->next_crypto->dh_server_signature = signature;
signature=NULL; /* ownership changed */
if (dh_build_k(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Cannot build k number");
goto error;
}
/* Send the MSG_NEWKEYS */
if (buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) {
goto error;
}
rc=packet_send(session);
ssh_log(session, SSH_LOG_PROTOCOL, "SSH_MSG_NEWKEYS sent");
return rc;
error:
return SSH_ERROR;
}
/*
static void sha_add(ssh_string str,SHACTX ctx){
sha1_update(ctx,str,string_len(str)+4);
#ifdef DEBUG_CRYPTO
ssh_print_hexa("partial hashed sessionid",str,string_len(str)+4);
#endif
}
*/
int make_sessionid(ssh_session session) {
ssh_string num = NULL;
ssh_string str = NULL;
ssh_buffer server_hash = NULL;
ssh_buffer client_hash = NULL;
ssh_buffer buf = NULL;
uint32_t len;
int rc = SSH_ERROR;
enter_function();
buf = ssh_buffer_new();
if (buf == NULL) {
return rc;
}
str = ssh_string_from_char(session->clientbanner);
if (str == NULL) {
goto error;
}
if (buffer_add_ssh_string(buf, str) < 0) {
goto error;
}
ssh_string_free(str);
str = ssh_string_from_char(session->serverbanner);
if (str == NULL) {
goto error;
}
if (buffer_add_ssh_string(buf, str) < 0) {
goto error;
}
if (session->client) {
server_hash = session->in_hashbuf;
client_hash = session->out_hashbuf;
} else {
server_hash = session->out_hashbuf;
client_hash = session->in_hashbuf;
}
if (buffer_add_u32(server_hash, 0) < 0) {
goto error;
}
if (buffer_add_u8(server_hash, 0) < 0) {
goto error;
}
if (buffer_add_u32(client_hash, 0) < 0) {
goto error;
}
if (buffer_add_u8(client_hash, 0) < 0) {
goto error;
}
len = ntohl(buffer_get_rest_len(client_hash));
if (buffer_add_u32(buf,len) < 0) {
goto error;
}
if (buffer_add_data(buf, buffer_get_rest(client_hash),
buffer_get_rest_len(client_hash)) < 0) {
goto error;
}
len = ntohl(buffer_get_rest_len(server_hash));
if (buffer_add_u32(buf, len) < 0) {
goto error;
}
if (buffer_add_data(buf, buffer_get_rest(server_hash),
buffer_get_rest_len(server_hash)) < 0) {
goto error;
}
len = ssh_string_len(session->next_crypto->server_pubkey) + 4;
if (buffer_add_data(buf, session->next_crypto->server_pubkey, len) < 0) {
goto error;
}
if(session->next_crypto->kex_type == SSH_KEX_DH_GROUP1_SHA1 ||
session->next_crypto->kex_type == SSH_KEX_DH_GROUP14_SHA1) {
num = make_bignum_string(session->next_crypto->e);
if (num == NULL) {
goto error;
}
len = ssh_string_len(num) + 4;
if (buffer_add_data(buf, num, len) < 0) {
goto error;
}
ssh_string_free(num);
num = make_bignum_string(session->next_crypto->f);
if (num == NULL) {
goto error;
}
len = ssh_string_len(num) + 4;
if (buffer_add_data(buf, num, len) < 0) {
goto error;
}
ssh_string_free(num);
#ifdef HAVE_ECDH
} else if (session->next_crypto->kex_type == SSH_KEX_ECDH_SHA2_NISTP256){
if(session->next_crypto->ecdh_client_pubkey == NULL ||
session->next_crypto->ecdh_server_pubkey == NULL){
ssh_log(session,SSH_LOG_WARNING,"ECDH parameted missing");
goto error;
}
buffer_add_ssh_string(buf,session->next_crypto->ecdh_client_pubkey);
buffer_add_ssh_string(buf,session->next_crypto->ecdh_server_pubkey);
#endif
}
num = make_bignum_string(session->next_crypto->k);
if (num == NULL) {
goto error;
}
len = ssh_string_len(num) + 4;
if (buffer_add_data(buf, num, len) < 0) {
goto error;
}
#ifdef DEBUG_CRYPTO
ssh_print_hexa("hash buffer", ssh_buffer_get_begin(buf), ssh_buffer_get_len(buf));
#endif
switch(session->next_crypto->kex_type){
case SSH_KEX_DH_GROUP1_SHA1:
case SSH_KEX_DH_GROUP14_SHA1:
session->next_crypto->digest_len = SHA_DIGEST_LENGTH;
session->next_crypto->mac_type = SSH_MAC_SHA1;
session->next_crypto->secret_hash = malloc(session->next_crypto->digest_len);
if(session->next_crypto->secret_hash == NULL){
ssh_set_error_oom(session);
goto error;
}
sha1(buffer_get_rest(buf), buffer_get_rest_len(buf),
session->next_crypto->secret_hash);
break;
case SSH_KEX_ECDH_SHA2_NISTP256:
session->next_crypto->digest_len = SHA256_DIGEST_LENGTH;
session->next_crypto->mac_type = SSH_MAC_SHA256;
session->next_crypto->secret_hash = malloc(session->next_crypto->digest_len);
if(session->next_crypto->secret_hash == NULL){
ssh_set_error_oom(session);
goto error;
}
sha256(buffer_get_rest(buf), buffer_get_rest_len(buf),
session->next_crypto->secret_hash);
break;
}
/* During the first kex, secret hash and session ID are equal. However, after
* a key re-exchange, a new secret hash is calculated. This hash will not replace
* but complement existing session id.
*/
if (!session->next_crypto->session_id){
session->next_crypto->session_id = malloc(session->next_crypto->digest_len);
if (session->next_crypto->session_id == NULL){
ssh_set_error_oom(session);
goto error;
}
memcpy(session->next_crypto->session_id, session->next_crypto->secret_hash,
session->next_crypto->digest_len);
}
#ifdef DEBUG_CRYPTO
printf("Session hash: ");
ssh_print_hexa("secret hash", session->next_crypto->secret_hash, session->next_crypto->digest_len);
ssh_print_hexa("session id", session->next_crypto->session_id, session->next_crypto->digest_len);
#endif
rc = SSH_OK;
error:
ssh_buffer_free(buf);
ssh_buffer_free(client_hash);
ssh_buffer_free(server_hash);
session->in_hashbuf = NULL;
session->out_hashbuf = NULL;
ssh_string_free(str);
ssh_string_free(num);
leave_function();
return rc;
}
int hashbufout_add_cookie(ssh_session session) {
session->out_hashbuf = ssh_buffer_new();
if (session->out_hashbuf == NULL) {
return -1;
}
if (buffer_add_u8(session->out_hashbuf, 20) < 0) {
buffer_reinit(session->out_hashbuf);
return -1;
}
if (session->server) {
if (buffer_add_data(session->out_hashbuf,
session->next_crypto->server_kex.cookie, 16) < 0) {
buffer_reinit(session->out_hashbuf);
return -1;
}
} else {
if (buffer_add_data(session->out_hashbuf,
session->next_crypto->client_kex.cookie, 16) < 0) {
buffer_reinit(session->out_hashbuf);
return -1;
}
}
return 0;
}
int hashbufin_add_cookie(ssh_session session, unsigned char *cookie) {
session->in_hashbuf = ssh_buffer_new();
if (session->in_hashbuf == NULL) {
return -1;
}
if (buffer_add_u8(session->in_hashbuf, 20) < 0) {
buffer_reinit(session->in_hashbuf);
return -1;
}
if (buffer_add_data(session->in_hashbuf,cookie, 16) < 0) {
buffer_reinit(session->in_hashbuf);
return -1;
}
return 0;
}
static int generate_one_key(ssh_string k,
struct ssh_crypto_struct *crypto, unsigned char *output, char letter) {
ssh_mac_ctx ctx;
ctx=ssh_mac_ctx_init(crypto->mac_type);
if (ctx == NULL) {
return -1;
}
ssh_mac_update(ctx, k, ssh_string_len(k) + 4);
ssh_mac_update(ctx, crypto->secret_hash, crypto->digest_len);
ssh_mac_update(ctx, &letter, 1);
ssh_mac_update(ctx, crypto->session_id, crypto->digest_len);
ssh_mac_final(output, ctx);
return 0;
}
int generate_session_keys(ssh_session session) {
ssh_string k_string = NULL;
ssh_mac_ctx ctx = NULL;
struct ssh_crypto_struct *crypto = session->next_crypto;
int rc = -1;
enter_function();
k_string = make_bignum_string(crypto->k);
if (k_string == NULL) {
ssh_set_error_oom(session);
goto error;
}
crypto->encryptIV = malloc(crypto->digest_len);
crypto->decryptIV = malloc(crypto->digest_len);
crypto->encryptkey = malloc(crypto->digest_len);
crypto->decryptkey = malloc(crypto->digest_len);
crypto->encryptMAC = malloc(crypto->digest_len);
crypto->decryptMAC = malloc(crypto->digest_len);
if(crypto->encryptIV == NULL || crypto->decryptIV == NULL ||
crypto->encryptkey == NULL || crypto->decryptkey == NULL ||
crypto->encryptMAC == NULL || crypto->decryptMAC == NULL){
ssh_set_error_oom(session);
goto error;
}
/* IV */
if (session->client) {
if (generate_one_key(k_string, crypto, crypto->encryptIV, 'A') < 0) {
goto error;
}
if (generate_one_key(k_string, crypto, crypto->decryptIV, 'B') < 0) {
goto error;
}
} else {
if (generate_one_key(k_string, crypto, crypto->decryptIV, 'A') < 0) {
goto error;
}
if (generate_one_key(k_string, crypto, crypto->encryptIV, 'B') < 0) {
goto error;
}
}
if (session->client) {
if (generate_one_key(k_string, crypto, crypto->encryptkey, 'C') < 0) {
goto error;
}
if (generate_one_key(k_string, crypto, crypto->decryptkey, 'D') < 0) {
goto error;
}
} else {
if (generate_one_key(k_string, crypto, crypto->decryptkey, 'C') < 0) {
goto error;
}
if (generate_one_key(k_string, crypto, crypto->encryptkey, 'D') < 0) {
goto error;
}
}
/* some ciphers need more than DIGEST_LEN bytes of input key */
if (crypto->out_cipher->keysize > crypto->digest_len * 8) {
crypto->encryptkey = realloc(crypto->encryptkey, crypto->digest_len * 2);
if(crypto->encryptkey == NULL)
goto error;
ctx = ssh_mac_ctx_init(crypto->mac_type);
if (ctx == NULL) {
goto error;
}
ssh_mac_update(ctx, k_string, ssh_string_len(k_string) + 4);
ssh_mac_update(ctx, crypto->session_id,
crypto->digest_len);
ssh_mac_update(ctx, crypto->encryptkey, crypto->digest_len);
ssh_mac_final(crypto->encryptkey + crypto->digest_len, ctx);
}
if (crypto->in_cipher->keysize > crypto->digest_len * 8) {
crypto->decryptkey = realloc(crypto->decryptkey, crypto->digest_len *2);
if(crypto->decryptkey == NULL)
goto error;
ctx = ssh_mac_ctx_init(crypto->mac_type);
ssh_mac_update(ctx, k_string, ssh_string_len(k_string) + 4);
ssh_mac_update(ctx, crypto->session_id,
crypto->digest_len);
ssh_mac_update(ctx, crypto->decryptkey, crypto->digest_len);
ssh_mac_final(crypto->decryptkey + crypto->digest_len, ctx);
}
if(session->client) {
if (generate_one_key(k_string, crypto, crypto->encryptMAC, 'E') < 0) {
goto error;
}
if (generate_one_key(k_string, crypto, crypto->decryptMAC, 'F') < 0) {
goto error;
}
} else {
if (generate_one_key(k_string, crypto, crypto->decryptMAC, 'E') < 0) {
goto error;
}
if (generate_one_key(k_string, crypto, crypto->encryptMAC, 'F') < 0) {
goto error;
}
}
#ifdef DEBUG_CRYPTO
ssh_print_hexa("Encrypt IV", crypto->encryptIV, SHA_DIGEST_LEN);
ssh_print_hexa("Decrypt IV", crypto->decryptIV, SHA_DIGEST_LEN);
ssh_print_hexa("Encryption key", crypto->encryptkey,
crypto->out_cipher->keysize);
ssh_print_hexa("Decryption key", crypto->decryptkey,
crypto->in_cipher->keysize);
ssh_print_hexa("Encryption MAC", crypto->encryptMAC, SHA_DIGEST_LEN);
ssh_print_hexa("Decryption MAC", crypto->decryptMAC, 20);
#endif
rc = 0;
error:
ssh_string_free(k_string);
leave_function();
return rc;
}
/**
* @addtogroup libssh_session
*
* @{
*/
/**
* @brief Allocates a buffer with the MD5 hash of the server public key.
*
* This function allows you to get a MD5 hash of the public key. You can then
* print this hash in a human-readable form to the user so that he is able to
* verify it. Use ssh_get_hexa() or ssh_print_hexa() to display it.
*
* @param[in] session The SSH session to use.
*
* @param[in] hash The buffer to allocate.
*
* @return The bytes allocated or < 0 on error.
*
* @warning It is very important that you verify at some moment that the hash
* matches a known server. If you don't do it, cryptography wont help
* you at making things secure
*
* @see ssh_is_server_known()
* @see ssh_get_hexa()
* @see ssh_print_hexa()
*/
int ssh_get_pubkey_hash(ssh_session session, unsigned char **hash) {
ssh_string pubkey;
MD5CTX ctx;
unsigned char *h;
if (session == NULL || hash == NULL) {
return SSH_ERROR;
}
*hash = NULL;
if (session->current_crypto == NULL ||
session->current_crypto->server_pubkey == NULL){
ssh_set_error(session,SSH_FATAL,"No current cryptographic context");
return SSH_ERROR;
}
h = malloc(sizeof(unsigned char) * MD5_DIGEST_LEN);
if (h == NULL) {
return SSH_ERROR;
}
ctx = md5_init();
if (ctx == NULL) {
SAFE_FREE(h);
return SSH_ERROR;
}
pubkey = session->current_crypto->server_pubkey;
md5_update(ctx, ssh_string_data(pubkey), ssh_string_len(pubkey));
md5_final(h, ctx);
*hash = h;
return MD5_DIGEST_LEN;
}
/**
* @brief Deallocate the hash obtained by ssh_get_pubkey_hash.
*
* This is required under Microsoft platform as this library might use a
* different C library than your software, hence a different heap.
*
* @param[in] hash The buffer to deallocate.
*
* @see ssh_get_pubkey_hash()
*/
void ssh_clean_pubkey_hash(unsigned char **hash) {
SAFE_FREE(*hash);
*hash = NULL;
}
/**
* @brief Get the server public key from a session.
*
* @param[in] session The session to get the key from.
*
* @param[out] key A pointer to store the allocated key. You need to free
* the key.
*
* @return SSH_OK on success, SSH_ERROR on errror.
*
* @see ssh_key_free()
*/
int ssh_get_publickey(ssh_session session, ssh_key *key)
{
if (session==NULL ||
session->current_crypto ==NULL ||
session->current_crypto->server_pubkey == NULL) {
return SSH_ERROR;
}
return ssh_pki_import_pubkey_blob(session->current_crypto->server_pubkey,
key);
}
/** @} */
/* vim: set ts=4 sw=4 et cindent: */
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