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For MS-CHAP, convert the password from UTF-8 to UCS-2

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The MS-CHAPv1 and MS-CHAPv2 RFCs specify that the password is a string
of "Unicode characters", which for Windows means UCS-2; thus the
password could be any even-length string of up to 512 bytes.

Instead of making the incompatible change of requiring the incoming
password to be UCS-2 encoded, assume the password is UTF-8 encoded and
convert it before using it in NtPasswordHash and
EncryptPwBlockWithPasswordHash.

Signed-off-by: Evan Broder <ebroder@mokafive.com>
This commit is contained in:
Evan Broder 2011-10-29 00:23:54 +03:00 committed by Jouni Malinen
parent 767885423b
commit c48183fca2
1 changed files with 80 additions and 26 deletions
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106
src/crypto/ms_funcs.c
View file

@ -19,6 +19,60 @@
#include "ms_funcs.h"
#include "crypto.h"
/**
* utf8_to_ucs2 - Convert UTF-8 string to UCS-2 encoding
* @utf8_string: UTF-8 string (IN)
* @utf8_string_len: Length of utf8_string (IN)
* @ucs2_buffer: UCS-2 buffer (OUT)
* @ucs2_buffer_size: Length of UCS-2 buffer (IN)
* @ucs2_string_size: Number of 2-byte words in the resulting UCS-2 string
* Returns: 0 on success, -1 on failure
*/
static int utf8_to_ucs2(const u8 *utf8_string, size_t utf8_string_len,
u8 *ucs2_buffer, size_t ucs2_buffer_size,
size_t *ucs2_string_size)
{
size_t i, j;
for (i = 0, j = 0; i < utf8_string_len; i++) {
u8 c = utf8_string[i];
if (j >= ucs2_buffer_size) {
/* input too long */
return -1;
}
if (c <= 0x7F) {
WPA_PUT_LE16(ucs2_buffer + j, c);
j += 2;
} else if (i == utf8_string_len - 1 ||
j >= ucs2_buffer_size - 1) {
/* incomplete surrogate */
return -1;
} else {
u8 c2 = utf8_string[++i];
if ((c & 0xE0) == 0xC0) {
/* two-byte encoding */
WPA_PUT_LE16(ucs2_buffer + j,
((c & 0x1F) << 6) | (c2 & 0x3F));
j += 2;
} else if (i == utf8_string_len ||
j >= ucs2_buffer_size - 1) {
/* incomplete surrogate */
return -1;
} else {
/* three-byte encoding */
u8 c3 = utf8_string[++i];
WPA_PUT_LE16(ucs2_buffer + j,
((c & 0xF) << 12) |
((c2 & 0x3F) << 6) | (c3 & 0x3F));
}
}
}
if (ucs2_string_size)
*ucs2_string_size = j / 2;
return 0;
}
/**
* challenge_hash - ChallengeHash() - RFC 2759, Sect. 8.2
@ -53,7 +107,7 @@ static int challenge_hash(const u8 *peer_challenge, const u8 *auth_challenge,
/**
* nt_password_hash - NtPasswordHash() - RFC 2759, Sect. 8.3
* @password: 0-to-256-unicode-char Password (IN; ASCII)
* @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @password_hash: 16-octet PasswordHash (OUT)
* Returns: 0 on success, -1 on failure
@ -62,18 +116,13 @@ int nt_password_hash(const u8 *password, size_t password_len,
u8 *password_hash)
{
u8 buf[512], *pos;
size_t i, len;
size_t len, max_len;
if (password_len > 256)
password_len = 256;
max_len = sizeof(buf);
if (utf8_to_ucs2(password, password_len, buf, max_len, &len) < 0)
return -1;
/* Convert password into unicode */
for (i = 0; i < password_len; i++) {
buf[2 * i] = password[i];
buf[2 * i + 1] = 0;
}
len = password_len * 2;
len *= 2;
pos = buf;
return md4_vector(1, (const u8 **) &pos, &len, password_hash);
}
@ -117,7 +166,7 @@ void challenge_response(const u8 *challenge, const u8 *password_hash,
* @peer_challenge: 16-octet PeerChallenge (IN)
* @username: 0-to-256-char UserName (IN)
* @username_len: Length of username
* @password: 0-to-256-unicode-char Password (IN; ASCII)
* @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @response: 24-octet Response (OUT)
* Returns: 0 on success, -1 on failure
@ -225,7 +274,7 @@ int generate_authenticator_response_pwhash(
/**
* generate_authenticator_response - GenerateAuthenticatorResponse() - RFC 2759, Sect. 8.7
* @password: 0-to-256-unicode-char Password (IN; ASCII)
* @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @nt_response: 24-octet NT-Response (IN)
* @peer_challenge: 16-octet PeerChallenge (IN)
@ -254,7 +303,7 @@ int generate_authenticator_response(const u8 *password, size_t password_len,
/**
* nt_challenge_response - NtChallengeResponse() - RFC 2433, Sect. A.5
* @challenge: 8-octet Challenge (IN)
* @password: 0-to-256-unicode-char Password (IN; ASCII)
* @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @response: 24-octet Response (OUT)
* Returns: 0 on success, -1 on failure
@ -375,7 +424,7 @@ int get_asymetric_start_key(const u8 *master_key, u8 *session_key,
/**
* encrypt_pw_block_with_password_hash - EncryptPwBlockWithPasswordHash() - RFC 2759, Sect. 8.10
* @password: 0-to-256-unicode-char Password (IN; ASCII)
* @password: 0-to-256-unicode-char Password (IN; UTF-8)
* @password_len: Length of password
* @password_hash: 16-octet PasswordHash (IN)
* @pw_block: 516-byte PwBlock (OUT)
@ -385,18 +434,23 @@ int encrypt_pw_block_with_password_hash(
const u8 *password, size_t password_len,
const u8 *password_hash, u8 *pw_block)
{
size_t i, offset;
size_t ucs2_len, offset;
u8 *pos;
if (password_len > 256)
os_memset(pw_block, 0, PWBLOCK_LEN);
if (utf8_to_ucs2(password, password_len, pw_block, 512, &ucs2_len) < 0)
return -1;
os_memset(pw_block, 0, PWBLOCK_LEN);
offset = (256 - password_len) * 2;
if (os_get_random(pw_block, offset) < 0)
if (ucs2_len > 256)
return -1;
for (i = 0; i < password_len; i++)
pw_block[offset + i * 2] = password[i];
offset = (256 - ucs2_len) * 2;
if (offset != 0) {
os_memmove(pw_block + offset, pw_block, ucs2_len * 2);
if (os_get_random(pw_block, offset) < 0)
return -1;
}
/*
* PasswordLength is 4 octets, but since the maximum password length is
* 256, only first two (in little endian byte order) can be non-zero.
@ -410,9 +464,9 @@ int encrypt_pw_block_with_password_hash(
/**
* new_password_encrypted_with_old_nt_password_hash - NewPasswordEncryptedWithOldNtPasswordHash() - RFC 2759, Sect. 8.9
* @new_password: 0-to-256-unicode-char NewPassword (IN; ASCII)
* @new_password: 0-to-256-unicode-char NewPassword (IN; UTF-8)
* @new_password_len: Length of new_password
* @old_password: 0-to-256-unicode-char OldPassword (IN; ASCII)
* @old_password: 0-to-256-unicode-char OldPassword (IN; UTF-8)
* @old_password_len: Length of old_password
* @encrypted_pw_block: 516-octet EncryptedPwBlock (OUT)
* Returns: 0 on success, -1 on failure
@ -450,9 +504,9 @@ void nt_password_hash_encrypted_with_block(const u8 *password_hash,
/**
* old_nt_password_hash_encrypted_with_new_nt_password_hash - OldNtPasswordHashEncryptedWithNewNtPasswordHash() - RFC 2759, Sect. 8.12
* @new_password: 0-to-256-unicode-char NewPassword (IN; ASCII)
* @new_password: 0-to-256-unicode-char NewPassword (IN; UTF-8)
* @new_password_len: Length of new_password
* @old_password: 0-to-256-unicode-char OldPassword (IN; ASCII)
* @old_password: 0-to-256-unicode-char OldPassword (IN; UTF-8)
* @old_password_len: Length of old_password
* @encrypted_password_hash: 16-octet EncryptedPasswordHash (OUT)
* Returns: 0 on success, -1 on failure