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eap-mschap: Add crypto functions for mschapv2

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Add the key-derivation and hash functions required for mschapv2.
The eap-mschapv2 protocol can be implemented on top of these functions.
This commit is contained in:
Markus Ongyerth 2016-12-14 23:15:28 +01:00 committed by Denis Kenzior
parent 6e729f6175
commit 1baa6ec04c
3 changed files with 409 additions and 0 deletions
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1
Makefile.am
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@ -76,6 +76,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h \
src/eap-wsc.h src/eap-wsc.c \ src/eap-wsc.h src/eap-wsc.c \
src/eap.h src/eap.c src/eap-md5.c \ src/eap.h src/eap.c src/eap-md5.c \
src/eap-tls.c src/eap-ttls.c \ src/eap-tls.c src/eap-ttls.c \
src/eap-mschapv2.c src/eap-mschapv2.h \
src/backtrace.h src/backtrace.c \ src/backtrace.h src/backtrace.c \
src/knownnetworks.h \ src/knownnetworks.h \
src/knownnetworks.c \ src/knownnetworks.c \

355
src/eap-mschapv2.c Normal file
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@ -0,0 +1,355 @@
/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2016 Markus Ongyerth. All rights reserved.
*
* This 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.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <ell/ell.h>
#include <ctype.h>
#include "eap-mschapv2.h"
/**
* Generate the asymetric start keys from our mschapv2 master key for MPPE
* This function is specified in:
* https://tools.ietf.org/html/draft-ietf-pppext-mschapv2-keys-02
*
* @master_key: The master key
* @session_key: the destination
* @session_len: The length of the requested key in octets (<= 20)
* @server: if the key should be generated for server side
* @send: if the send or the receive key should be generated
*
* Returns: true on success, false if hash/encrypt couldn't be done
**/
bool mschapv2_get_asymmetric_start_key(const uint8_t master_key[static 16],
uint8_t *session_key, size_t session_len,
bool server, bool send)
{
static const uint8_t magic2[] = {
0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69,
0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20,
0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20, 0x6b, 0x65, 0x79,
0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x73,
0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73, 0x69, 0x64, 0x65,
0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20,
0x6b, 0x65, 0x79, 0x2e
};
static const uint8_t magic3[] = {
0x4f, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x63, 0x6c, 0x69,
0x65, 0x6e, 0x74, 0x20, 0x73, 0x69, 0x64, 0x65, 0x2c, 0x20,
0x74, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
0x65, 0x20, 0x72, 0x65, 0x63, 0x65, 0x69, 0x76, 0x65, 0x20,
0x6b, 0x65, 0x79, 0x3b, 0x20, 0x6f, 0x6e, 0x20, 0x74, 0x68,
0x65, 0x20, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x73,
0x69, 0x64, 0x65, 0x2c, 0x20, 0x69, 0x74, 0x20, 0x69, 0x73,
0x20, 0x74, 0x68, 0x65, 0x20, 0x73, 0x65, 0x6e, 0x64, 0x20,
0x6b, 0x65, 0x79, 0x2e
};
static const uint8_t shs_pad1[] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
static const uint8_t shs_pad2[] = {
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2
};
const uint8_t *magic;
struct l_checksum *check;
if (send == server)
magic = magic3;
else
magic = magic2;
check = l_checksum_new(L_CHECKSUM_SHA1);
if (!check)
return false;
l_checksum_update(check, master_key, 16);
l_checksum_update(check, shs_pad1, 40);
l_checksum_update(check, magic, 84);
l_checksum_update(check, shs_pad2, 40);
l_checksum_get_digest(check, session_key, session_len);
l_checksum_free(check);
return true;
}
/**
* Generate the master key for MPPE from mschapv2
* This function is specified in:
* https://tools.ietf.org/html/draft-ietf-pppext-mschapv2-keys-02
*
* @pw_hash_hash: The MD4 hash of the password hash
* @nt_response: The nt_response generated for mschapv2
* @master_key: The destination
*
* Returns: true on success, false if hash/encrypt couldn't be done
**/
bool mschapv2_get_master_key(const uint8_t pw_hash_hash[static 16],
const uint8_t nt_response[static 24],
uint8_t master_key[static 16])
{
static const uint8_t magic[] = {
0x54, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20, 0x74,
0x68, 0x65, 0x20, 0x4d, 0x50, 0x50, 0x45, 0x20, 0x4d,
0x61, 0x73, 0x74, 0x65, 0x72, 0x20, 0x4b, 0x65, 0x79
};
struct l_checksum *check;
check = l_checksum_new(L_CHECKSUM_SHA1);
if (!check)
return false;
l_checksum_update(check, pw_hash_hash, 16);
l_checksum_update(check, nt_response, 24);
l_checksum_update(check, magic, sizeof(magic));
l_checksum_get_digest(check, master_key, 16);
l_checksum_free(check);
return true;
}
/**
* Internal function to generate the challenge used in nt_response
* https://tools.ietf.org/html/rfc2759
*
* @peer_challenge: The challenge generated by the peer (us)
* @server_challenge: The challenge generated by the authenticator
* @user: The username utf8 encoded
* @challenge: The destination
*
* Returns: true on success, false if hash/encrypt couldn't be done
**/
static bool mschapv2_challenge_hash(const uint8_t *peer_challenge,
const uint8_t *server_challenge,
const char *user, uint8_t challenge[static 8])
{
struct l_checksum *check;
check = l_checksum_new(L_CHECKSUM_SHA1);
if (!check)
return false;
l_checksum_update(check, peer_challenge, 16);
l_checksum_update(check, server_challenge, 16);
l_checksum_update(check, user, strlen(user));
l_checksum_get_digest(check, challenge, 8);
l_checksum_free(check);
return true;
}
/**
* Hash the utf8 encoded nt password.
* It is asumed, that the password is valid utf8!
* The rfc says "unicode-char", but never specifies which encoding.
* This function converts the password to ucs-2.
* The example in the code uses LE for the unicode chars, so it is forced here.
* https://tools.ietf.org/html/draft-ietf-pppext-mschap-00#ref-8
*/
bool mschapv2_nt_password_hash(const char *password, uint8_t hash[static 16])
{
size_t size = l_utf8_strlen(password);
size_t bsize = strlen(password);
uint16_t buffer[size];
unsigned int i, pos;
struct l_checksum *check;
for (i = 0, pos = 0; i < size; ++i) {
wchar_t val;
pos += l_utf8_get_codepoint(password + pos, bsize - pos, &val);
if (val > 0xFFFF) {
l_error("Encountered password with value not valid in ucs-2");
return false;
}
buffer[i] = L_CPU_TO_LE16(val);
}
check = l_checksum_new(L_CHECKSUM_MD4);
if (!check)
return false;
l_checksum_update(check, (uint8_t *) buffer, size * 2);
l_checksum_get_digest(check, hash, 16);
l_checksum_free(check);
return true;
}
/**
* Internal function for generate_nt_response.
* The DES keys specified for generate_nt_response are 56bit, while the api we
* use takes 64bit keys, so we have to generate the parity bits.
**/
static bool mschapv2_des_encrypt(const uint8_t challenge[static 8],
const uint8_t key[static 7],
uint8_t cipher_text[static 8])
{
uint8_t pkey[8], tmp;
int i;
struct l_cipher *cipher;
uint8_t next;
for (i = 0, next = 0; i < 7; ++i) {
tmp = key[i];
pkey[i] = (tmp >> i) | next | 1;
next = tmp << (7 - i);
}
pkey[i] = next | 1;
cipher = l_cipher_new(L_CIPHER_DES, pkey, 8);
if (!cipher)
return false;
l_cipher_encrypt(cipher, challenge, cipher_text, 8);
l_cipher_free(cipher);
return true;
}
/**
* Generate the nt_response for mschapv2.
* This function is specified in:
* https://tools.ietf.org/html/rfc2759
*
* @password_hash: The MD4 hash of the ucs2 encoded user password
* @peer_challenge: the challenge generated by the peer (us)
* @server_challenge: the challenge generated by the authenticator
* @user: The username, utf8 encoded
* @nt_response: The destination
*
* Returns: true on success, false if hash/encrypt couldn't be done
**/
bool mschapv2_generate_nt_response(const uint8_t password_hash[static 16],
const uint8_t peer_challenge[static 16],
const uint8_t server_challenge[static 16],
const char *user, uint8_t response[static 24])
{
uint8_t challenge[8];
uint8_t buffer[21];
memset(buffer, 0, sizeof(buffer));
memcpy(buffer, password_hash, 16);
if (!mschapv2_challenge_hash(peer_challenge, server_challenge, user,
challenge))
return false;
if (!mschapv2_des_encrypt(challenge, buffer + 0, response + 0)
|| !mschapv2_des_encrypt(challenge, buffer + 7, response + 8)
|| !mschapv2_des_encrypt(challenge, buffer + 14, response + 16))
return false;
return true;
}
/**
* Generate the mschapv2 authenticator response for verifying authenticator
* This function is specified in:
* https://tools.ietf.org/html/rfc2759
*
* @password_hash_hash: The MD4 hash of the password hash
* @nt_response: The nt_response generated for this exchange
* @peer_challenge: The challenge generated by the peer (us)
* @server_challenge: The challenge generated by the authenticator
* @user: The username utf8 encoded
* @response: The destination
*
* Returns: true on success, false if hash/encrypt couldn't be done
**/
bool mschapv2_generate_authenticator_response(
const uint8_t pw_hash_hash[static 16],
const uint8_t nt_response[static 24],
const uint8_t peer_challenge[static 16],
const uint8_t server_challenge[static 16],
const char *user, char response[static 42])
{
static const uint8_t magic1[] =
{ 0x4D, 0x61, 0x67, 0x69, 0x63, 0x20, 0x73, 0x65, 0x72, 0x76,
0x65, 0x72, 0x20, 0x74, 0x6F, 0x20, 0x63, 0x6C, 0x69, 0x65,
0x6E, 0x74, 0x20, 0x73, 0x69, 0x67, 0x6E, 0x69, 0x6E, 0x67,
0x20, 0x63, 0x6F, 0x6E, 0x73, 0x74, 0x61, 0x6E, 0x74};
static const uint8_t magic2[] =
{ 0x50, 0x61, 0x64, 0x20, 0x74, 0x6F, 0x20, 0x6D, 0x61, 0x6B,
0x65, 0x20, 0x69, 0x74, 0x20, 0x64, 0x6F, 0x20, 0x6D, 0x6F,
0x72, 0x65, 0x20, 0x74, 0x68, 0x61, 0x6E, 0x20, 0x6F, 0x6E,
0x65, 0x20, 0x69, 0x74, 0x65, 0x72, 0x61, 0x74, 0x69, 0x6F,
0x6E};
uint8_t digest[20];
uint8_t challenge[8];
char *ascii;
int i;
struct l_checksum *check;
check = l_checksum_new(L_CHECKSUM_SHA1);
if (!check)
return false;
l_checksum_update(check, pw_hash_hash, 16);
l_checksum_update(check, nt_response, 24);
l_checksum_update(check, magic1, sizeof(magic1));
l_checksum_get_digest(check, digest, sizeof(digest));
l_checksum_free(check);
if (!mschapv2_challenge_hash(peer_challenge, server_challenge, user,
challenge))
return false;
check = l_checksum_new(L_CHECKSUM_SHA1);
if (!check)
return false;
l_checksum_update(check, digest, sizeof(digest));
l_checksum_update(check, challenge, sizeof(challenge));
l_checksum_update(check, magic2, sizeof(magic2));
l_checksum_get_digest(check, digest, sizeof(digest));
l_checksum_free(check);
response[0] = 'S';
response[1] = '=';
ascii = l_util_hexstring(digest, sizeof(digest));
if (!ascii)
return false;
for (i = 0; i < 40; ++i) {
response[i + 2] = toupper(ascii[i]);
}
l_free(ascii);
return true;
}

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src/eap-mschapv2.h Normal file
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@ -0,0 +1,53 @@
/*
*
* Wireless daemon for Linux
*
* Copyright (C) 2016 Markus Ongyerth. All rights reserved.
*
* This 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.
*
* This 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
bool mschapv2_get_asymmetric_start_key(const uint8_t master_key[static 16],
uint8_t *session_key, size_t session_len,
bool server, bool send);
bool mschapv2_get_master_key(const uint8_t pw_hash_hash[static 16],
const uint8_t nt_response[static 24],
uint8_t master_key[static 16]);
bool mschapv2_nt_password_hash(const char *password, uint8_t hash[16]);
bool mschapv2_generate_nt_response(const uint8_t password_hash[static 16],
const uint8_t peer_challenge[static 16],
const uint8_t server_challenge[static 16],
const char *user,
uint8_t response[static 24]);
bool mschapv2_generate_authenticator_response(
const uint8_t pw_hash_hash[static 16],
const uint8_t nt_response[static 24],
const uint8_t peer_challenge[static 16],
const uint8_t server_challenge[static 16],
const char *user, char response[static 42]);