[PATCH] For MS-CHAP, convert the password from UTF-8 to UCS-2.
Evan Broder
evan at ebroder.net
Sat Oct 22 14:21:51 EDT 2011
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 <evan at ebroder.net>
---
src/crypto/ms_funcs.c | 107 ++++++++++++++++++++++++++++++++++++-------------
1 files changed, 79 insertions(+), 28 deletions(-)
diff --git a/src/crypto/ms_funcs.c b/src/crypto/ms_funcs.c
index dae15ab..29b0c99 100644
--- a/src/crypto/ms_funcs.c
+++ b/src/crypto/ms_funcs.c
@@ -19,6 +19,52 @@
#include "ms_funcs.h"
#include "crypto.h"
+/**
+ * utf8_to_ucs2
+ * @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 2-byte words) (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,
+ u16 *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) {
+ ucs2_buffer[j++] = host_to_le16(c);
+ } 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 */
+ ucs2_buffer[j++] = host_to_le16(((c & 0x1F) << 6) | (c2 & 0x3F));
+ } else if (i == utf8_string_len || j == ucs2_buffer_size - 1) {
+ /* incomplete surrogate */
+ return -1;
+ } else {
+ /* three-byte encoding */
+ u8 c3 = utf8_string[++i];
+ ucs2_buffer[j++] = host_to_le16(((c & 0xF) << 12) | ((c2 & 0x3F) << 6) | (c3 & 0x3F));
+ }
+ }
+ }
+
+ if (ucs2_string_size)
+ *ucs2_string_size = j;
+ return 0;
+}
/**
* challenge_hash - ChallengeHash() - RFC 2759, Sect. 8.2
@@ -53,7 +99,7 @@ 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
@@ -61,20 +107,18 @@ static int challenge_hash(const u8 *peer_challenge, const u8 *auth_challenge,
int nt_password_hash(const u8 *password, size_t password_len,
u8 *password_hash)
{
- u8 buf[512], *pos;
- size_t i, len;
-
- if (password_len > 256)
- password_len = 256;
+ u16 buf[256];
+ u8 *pos;
+ size_t len, max_len;
- /* Convert password into unicode */
- for (i = 0; i < password_len; i++) {
- buf[2 * i] = password[i];
- buf[2 * i + 1] = 0;
- }
+ max_len = sizeof(buf) / sizeof(buf[0]);
+ if (-1 == utf8_to_ucs2(password, password_len,
+ buf, max_len,
+ &len))
+ return -1;
- len = password_len * 2;
- pos = buf;
+ len *= 2;
+ pos = (u8 *)buf;
return md4_vector(1, (const u8 **) &pos, &len, password_hash);
}
@@ -117,7 +161,7 @@ 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 +269,7 @@ 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 +298,7 @@ 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 +419,7 @@ 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 +429,25 @@ 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 (-1 == utf8_to_ucs2(password, password_len,
+ (u16 *)pw_block, 256,
+ &ucs2_len))
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 +461,9 @@ 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 +501,9 @@ 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
--
1.7.5.4
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