tg/mtproto-common.c

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/*
This file is part of telegram-client.
Telegram-client is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
Telegram-client 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this telegram-client. If not, see <http://www.gnu.org/licenses/>.
Copyright Nikolay Durov, Andrey Lopatin 2012-2013
Copyright Vitaly Valtman 2013
*/
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#define _FILE_OFFSET_BITS 64
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <aio.h>
#include <netdb.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include <openssl/pem.h>
#include <openssl/aes.h>
#include <openssl/sha.h>
#include "mtproto-common.h"
#include "interface.h"
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long long rsa_encrypted_chunks, rsa_decrypted_chunks;
BN_CTX *BN_ctx;
int verbosity;
int get_random_bytes (void *buf, int n) {
int r = 0, h = open ("/dev/random", O_RDONLY | O_NONBLOCK);
if (h >= 0) {
r = read (h, buf, n);
if (r > 0) {
if (verbosity >= 3) {
logprintf ( "added %d bytes of real entropy to secure random numbers seed\n", r);
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}
}
close (h);
}
if (r < n) {
h = open ("/dev/urandom", O_RDONLY);
if (h < 0) {
return r;
}
int s = read (h, buf + r, n - r);
close (h);
if (s < 0) {
return r;
}
r += s;
}
if (r >= (int)sizeof (long)) {
*(long *)buf ^= lrand48 ();
srand48 (*(long *)buf);
}
return r;
}
void prng_seed (const char *password_filename, int password_length) {
unsigned char *a = calloc (64 + password_length, 1);
assert (a != NULL);
long long r = rdtsc ();
struct timespec T;
assert (clock_gettime(CLOCK_REALTIME, &T) >= 0);
memcpy (a, &T.tv_sec, 4);
memcpy (a+4, &T.tv_nsec, 4);
memcpy (a+8, &r, 8);
unsigned short p = getpid ();
memcpy (a + 16, &p, 2);
int s = get_random_bytes (a + 18, 32) + 18;
if (password_filename) {
int fd = open (password_filename, O_RDONLY);
if (fd < 0) {
logprintf ( "Warning: fail to open password file - \"%s\", %m.\n", password_filename);
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} else {
int l = read (fd, a + s, password_length);
if (l < 0) {
logprintf ( "Warning: fail to read password file - \"%s\", %m.\n", password_filename);
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} else {
if (verbosity > 0) {
logprintf ( "read %d bytes from password file.\n", l);
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}
s += l;
}
close (fd);
}
}
RAND_seed (a, s);
BN_ctx = BN_CTX_new ();
memset (a, 0, s);
free (a);
}
int serialize_bignum (BIGNUM *b, char *buffer, int maxlen) {
int itslen = BN_num_bytes (b);
int reqlen;
if (itslen < 254) {
reqlen = itslen + 1;
} else {
reqlen = itslen + 4;
}
int newlen = (reqlen + 3) & -4;
int pad = newlen - reqlen;
reqlen = newlen;
if (reqlen > maxlen) {
return -reqlen;
}
if (itslen < 254) {
*buffer++ = itslen;
} else {
*(int *)buffer = (itslen << 8) + 0xfe;
buffer += 4;
}
int l = BN_bn2bin (b, (unsigned char *)buffer);
assert (l == itslen);
buffer += l;
while (pad --> 0) {
*buffer++ = 0;
}
return reqlen;
}
long long compute_rsa_key_fingerprint (RSA *key) {
static char tempbuff[4096];
static unsigned char sha[20];
assert (key->n && key->e);
int l1 = serialize_bignum (key->n, tempbuff, 4096);
assert (l1 > 0);
int l2 = serialize_bignum (key->e, tempbuff + l1, 4096 - l1);
assert (l2 > 0 && l1 + l2 <= 4096);
SHA1 ((unsigned char *)tempbuff, l1 + l2, sha);
return *(long long *)(sha + 12);
}
void out_cstring (const char *str, long len) {
assert (len >= 0 && len < (1 << 24));
assert ((char *) packet_ptr + len + 8 < (char *) (packet_buffer + PACKET_BUFFER_SIZE));
char *dest = (char *) packet_ptr;
if (len < 254) {
*dest++ = len;
} else {
*packet_ptr = (len << 8) + 0xfe;
dest += 4;
}
memcpy (dest, str, len);
dest += len;
while ((long) dest & 3) {
*dest++ = 0;
}
packet_ptr = (int *) dest;
}
void out_cstring_careful (const char *str, long len) {
assert (len >= 0 && len < (1 << 24));
assert ((char *) packet_ptr + len + 8 < (char *) (packet_buffer + PACKET_BUFFER_SIZE));
char *dest = (char *) packet_ptr;
if (len < 254) {
dest++;
if (dest != str) {
memmove (dest, str, len);
}
dest[-1] = len;
} else {
dest += 4;
if (dest != str) {
memmove (dest, str, len);
}
*packet_ptr = (len << 8) + 0xfe;
}
dest += len;
while ((long) dest & 3) {
*dest++ = 0;
}
packet_ptr = (int *) dest;
}
void out_data (const char *data, long len) {
assert (len >= 0 && len < (1 << 24) && !(len & 3));
assert ((char *) packet_ptr + len + 8 < (char *) (packet_buffer + PACKET_BUFFER_SIZE));
memcpy (packet_ptr, data, len);
packet_ptr += len >> 2;
}
int *in_ptr, *in_end;
int fetch_bignum (BIGNUM *x) {
int l = prefetch_strlen ();
if (l < 0) {
return l;
}
char *str = fetch_str (l);
assert (BN_bin2bn ((unsigned char *) str, l, x) == x);
return l;
}
int pad_rsa_encrypt (char *from, int from_len, char *to, int size, BIGNUM *N, BIGNUM *E) {
int pad = (255000 - from_len - 32) % 255 + 32;
int chunks = (from_len + pad) / 255;
int bits = BN_num_bits (N);
assert (bits >= 2041 && bits <= 2048);
assert (from_len > 0 && from_len <= 2550);
assert (size >= chunks * 256);
assert (RAND_pseudo_bytes ((unsigned char *) from + from_len, pad) >= 0);
int i;
BIGNUM x, y;
BN_init (&x);
BN_init (&y);
rsa_encrypted_chunks += chunks;
for (i = 0; i < chunks; i++) {
BN_bin2bn ((unsigned char *) from, 255, &x);
assert (BN_mod_exp (&y, &x, E, N, BN_ctx) == 1);
unsigned l = 256 - BN_num_bytes (&y);
assert (l <= 256);
memset (to, 0, l);
BN_bn2bin (&y, (unsigned char *) to + l);
to += 256;
}
BN_free (&x);
BN_free (&y);
return chunks * 256;
}
int pad_rsa_decrypt (char *from, int from_len, char *to, int size, BIGNUM *N, BIGNUM *D) {
if (from_len < 0 || from_len > 0x1000 || (from_len & 0xff)) {
return -1;
}
int chunks = (from_len >> 8);
int bits = BN_num_bits (N);
assert (bits >= 2041 && bits <= 2048);
assert (size >= chunks * 255);
int i;
BIGNUM x, y;
BN_init (&x);
BN_init (&y);
for (i = 0; i < chunks; i++) {
++rsa_decrypted_chunks;
BN_bin2bn ((unsigned char *) from, 256, &x);
assert (BN_mod_exp (&y, &x, D, N, BN_ctx) == 1);
int l = BN_num_bytes (&y);
if (l > 255) {
BN_free (&x);
BN_free (&y);
return -1;
}
assert (l >= 0 && l <= 255);
memset (to, 0, 255 - l);
BN_bn2bin (&y, (unsigned char *) to + 255 - l);
to += 255;
}
BN_free (&x);
BN_free (&y);
return chunks * 255;
}
unsigned char aes_key_raw[32], aes_iv[32];
AES_KEY aes_key;
void init_aes_unauth (const char server_nonce[16], const char hidden_client_nonce[32], int encrypt) {
static unsigned char buffer[64], hash[20];
memcpy (buffer, hidden_client_nonce, 32);
memcpy (buffer + 32, server_nonce, 16);
SHA1 (buffer, 48, aes_key_raw);
memcpy (buffer + 32, hidden_client_nonce, 32);
SHA1 (buffer, 64, aes_iv + 8);
memcpy (buffer, server_nonce, 16);
memcpy (buffer + 16, hidden_client_nonce, 32);
SHA1 (buffer, 48, hash);
memcpy (aes_key_raw + 20, hash, 12);
memcpy (aes_iv, hash + 12, 8);
memcpy (aes_iv + 28, hidden_client_nonce, 4);
if (encrypt == AES_ENCRYPT) {
AES_set_encrypt_key (aes_key_raw, 32*8, &aes_key);
} else {
AES_set_decrypt_key (aes_key_raw, 32*8, &aes_key);
}
}
void init_aes_auth (char auth_key[192], char msg_key[16], int encrypt) {
static unsigned char buffer[48], hash[20];
// sha1_a = SHA1 (msg_key + substr (auth_key, 0, 32));
// sha1_b = SHA1 (substr (auth_key, 32, 16) + msg_key + substr (auth_key, 48, 16));
// sha1_с = SHA1 (substr (auth_key, 64, 32) + msg_key);
// sha1_d = SHA1 (msg_key + substr (auth_key, 96, 32));
// aes_key = substr (sha1_a, 0, 8) + substr (sha1_b, 8, 12) + substr (sha1_c, 4, 12);
// aes_iv = substr (sha1_a, 8, 12) + substr (sha1_b, 0, 8) + substr (sha1_c, 16, 4) + substr (sha1_d, 0, 8);
memcpy (buffer, msg_key, 16);
memcpy (buffer + 16, auth_key, 32);
SHA1 (buffer, 48, hash);
memcpy (aes_key_raw, hash, 8);
memcpy (aes_iv, hash + 8, 12);
memcpy (buffer, auth_key + 32, 16);
memcpy (buffer + 16, msg_key, 16);
memcpy (buffer + 32, auth_key + 48, 16);
SHA1 (buffer, 48, hash);
memcpy (aes_key_raw + 8, hash + 8, 12);
memcpy (aes_iv + 12, hash, 8);
memcpy (buffer, auth_key + 64, 32);
memcpy (buffer + 32, msg_key, 16);
SHA1 (buffer, 48, hash);
memcpy (aes_key_raw + 20, hash + 4, 12);
memcpy (aes_iv + 20, hash + 16, 4);
memcpy (buffer, msg_key, 16);
memcpy (buffer + 16, auth_key + 96, 32);
SHA1 (buffer, 48, hash);
memcpy (aes_iv + 24, hash, 8);
if (encrypt == AES_ENCRYPT) {
AES_set_encrypt_key (aes_key_raw, 32*8, &aes_key);
} else {
AES_set_decrypt_key (aes_key_raw, 32*8, &aes_key);
}
}
int pad_aes_encrypt (char *from, int from_len, char *to, int size) {
int padded_size = (from_len + 15) & -16;
assert (from_len > 0 && padded_size <= size);
if (from_len < padded_size) {
assert (RAND_pseudo_bytes ((unsigned char *) from + from_len, padded_size - from_len) >= 0);
}
AES_ige_encrypt ((unsigned char *) from, (unsigned char *) to, padded_size, &aes_key, aes_iv, AES_ENCRYPT);
return padded_size;
}
int pad_aes_decrypt (char *from, int from_len, char *to, int size) {
if (from_len <= 0 || from_len > size || (from_len & 15)) {
return -1;
}
AES_ige_encrypt ((unsigned char *) from, (unsigned char *) to, from_len, &aes_key, aes_iv, AES_DECRYPT);
return from_len;
}