mschapv2.c File Reference

MS-CHAPv2 authentication. More...

#include <stdio.h>
#include <string.h>
#include <byteswap.h>
#include <ipxe/md4.h>
#include <ipxe/sha1.h>
#include <ipxe/des.h>
#include <ipxe/mschapv2.h>

Go to the source code of this file.

Data Structures
union	mschapv2_context
	MS-CHAPv2 context block. More...
union	mschapv2_challenge_hash
	MS-CHAPv2 challenge hash. More...
union	mschapv2_password_hash
	MS-CHAPv2 password hash. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static void	mschapv2_challenge_hash (union mschapv2_context *ctx, const struct mschapv2_challenge *challenge, const struct mschapv2_challenge *peer, const char *username, union mschapv2_challenge_hash *chash)
	Calculate MS-CHAPv2 challenge hash. More...
static void	mschapv2_password_hash (union mschapv2_context *ctx, const char *password, union mschapv2_password_hash *phash)
	Calculate MS-CHAPv2 password hash. More...
static void	mschapv2_hash_hash (union mschapv2_context *ctx, union mschapv2_password_hash *phash)
	Hash the MS-CHAPv2 password hash. More...
static void	mschapv2_expand_hash (union mschapv2_context *ctx, union mschapv2_password_hash *phash)
	Expand MS-CHAPv2 password hash by inserting DES dummy parity bits. More...
static void	mschapv2_challenge_response (union mschapv2_context *ctx, const union mschapv2_challenge_hash *chash, const union mschapv2_password_hash *phash, struct mschapv2_nt_response *nt)
	Calculate MS-CHAPv2 challenge response. More...
void	mschapv2_response (const char *username, const char *password, const struct mschapv2_challenge *challenge, const struct mschapv2_challenge *peer, struct mschapv2_response *response)
	Calculate MS-CHAPv2 challenge response. More...
void	mschapv2_auth (const char *username, const char *password, const struct mschapv2_challenge *challenge, const struct mschapv2_response *response, struct mschapv2_auth *auth)
	Calculate MS-CHAPv2 authenticator response. More...

Variables
static const char	mschapv2_magic1 [39]
	MS-CHAPv2 magic constant 1. More...
static const char	mschapv2_magic2 [41]
	MS-CHAPv2 magic constant 2. More...

Detailed Description

MS-CHAPv2 authentication.

The algorithms used for MS-CHAPv2 authentication are defined in RFC 2759 section 8.

Definition in file mschapv2.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

mschapv2_challenge_hash()

static void mschapv2_challenge_hash ( union mschapv2_context *  ctx, const struct mschapv2_challenge *  challenge, const struct mschapv2_challenge *  peer, const char *  username, union mschapv2_challenge_hash *  chash  )

static

Calculate MS-CHAPv2 challenge hash.

Parameters

ctx	Context block
challenge	Authenticator challenge
peer	Peer challenge
username	User name (or NULL to use empty string)
chash	Challenge hash to fill in

This is the ChallengeHash() function as documented in RFC 2759 section 8.2.

Definition at line 119 of file mschapv2.c.

                                                                 {
        struct digest_algorithm *sha1 = &sha1_algorithm;

        /* Calculate SHA-1 hash of challenges and username */
        digest_init ( sha1, ctx->sha1 );
        digest_update ( sha1, ctx->sha1, peer, sizeof ( *peer ) );
        digest_update ( sha1, ctx->sha1, challenge, sizeof ( *challenge ) );
        if ( username ) {
                digest_update ( sha1, ctx->sha1, username,
                                strlen ( username ) );
        }
        digest_final ( sha1, ctx->sha1, chash->sha1 );
        DBGC ( ctx, "MSCHAPv2 authenticator challenge:\n" );
        DBGC_HDA ( ctx, 0, challenge, sizeof ( *challenge ) );
        DBGC ( ctx, "MSCHAPv2 peer challenge:\n" );
        DBGC_HDA ( ctx, 0, peer, sizeof ( *peer ) );
        DBGC ( ctx, "MSCHAPv2 challenge hash:\n" );
        DBGC_HDA ( ctx, 0, chash->des, sizeof ( chash->des ) );
}

References ctx, DBGC, DBGC_HDA, mschapv2_challenge_hash::des, peer, mschapv2_challenge_hash::sha1, sha1_algorithm, and strlen().

Referenced by mschapv2_auth(), and mschapv2_response().

mschapv2_password_hash()

static void mschapv2_password_hash ( union mschapv2_context *  ctx, const char *  password, union mschapv2_password_hash *  phash  )

static

Calculate MS-CHAPv2 password hash.

Parameters

ctx	Context block
password	Password (or NULL to use empty string)
phash	Password hash to fill in

This is the NtPasswordHash() function as documented in RFC 2759 section 8.3.

Definition at line 153 of file mschapv2.c.

                                                                           {
        struct digest_algorithm *md4 = &md4_algorithm;
        uint16_t wc;
        uint8_t c;

        /* Construct zero-padded MD4 hash of encoded password */
        memset ( phash, 0, sizeof ( *phash ) );
        digest_init ( md4, ctx->md4 );
        if ( password ) {
                while ( ( c = *(password++) ) ) {
                        wc = cpu_to_le16 ( c );
                        digest_update ( md4, ctx->md4, &wc, sizeof ( wc ) );
                }
        }
        digest_final ( md4, ctx->md4, phash->md4 );
        DBGC ( ctx, "MSCHAPv2 password hash:\n" );
        DBGC_HDA ( ctx, 0, phash->md4, sizeof ( phash->md4 ) );
}

References c, cpu_to_le16, ctx, DBGC, DBGC_HDA, mschapv2_password_hash::md4, md4_algorithm, memset(), and wc.

Referenced by mschapv2_auth(), and mschapv2_response().

mschapv2_hash_hash()

static void mschapv2_hash_hash ( union mschapv2_context *  ctx, union mschapv2_password_hash *  phash  )

static

Hash the MS-CHAPv2 password hash.

Parameters

ctx	Context block
phash	Password hash to be rehashed

This is the HashNtPasswordHash() function as documented in RFC 2759 section 8.4.

Definition at line 183 of file mschapv2.c.

                                                                       {
        struct digest_algorithm *md4 = &md4_algorithm;

        /* Calculate MD4 hash of existing MD4 hash */
        digest_init ( md4, ctx->md4 );
        digest_update ( md4, ctx->md4, phash->md4, sizeof ( phash->md4 ) );
        digest_final ( md4, ctx->md4, phash->md4 );
        DBGC ( ctx, "MSCHAPv2 password hash hash:\n" );
        DBGC_HDA ( ctx, 0, phash->md4, sizeof ( phash->md4 ) );
}

References ctx, DBGC, DBGC_HDA, mschapv2_password_hash::md4, and md4_algorithm.

Referenced by mschapv2_auth().

mschapv2_expand_hash()

static void mschapv2_expand_hash ( union mschapv2_context *  ctx, union mschapv2_password_hash *  phash  )

static

Expand MS-CHAPv2 password hash by inserting DES dummy parity bits.

Parameters

ctx	Context block
phash	Password hash to expand

This is part of the DesEncrypt() function as documented in RFC 2759 section 8.6.

Definition at line 204 of file mschapv2.c.

                                                                         {
        uint8_t *dst;
        uint8_t *src;
        unsigned int i;

        /* Expand password hash by inserting (unused) DES parity bits */
        for ( i = ( sizeof ( phash->expand ) - 1 ) ; i > 0 ; i-- ) {
                dst = &phash->expand[i];
                src = ( dst - ( i / 8 ) );
                *dst = ( ( ( src[-1] << 8 ) | src[0] ) >> ( i % 8 ) );
        }
        DBGC ( ctx, "MSCHAPv2 expanded password hash:\n" );
        DBGC_HDA ( ctx, 0, phash->expand, sizeof ( phash->expand ) );
}

References ctx, DBGC, DBGC_HDA, dst, mschapv2_password_hash::expand, and src.

Referenced by mschapv2_response().

mschapv2_challenge_response()

static void mschapv2_challenge_response ( union mschapv2_context *  ctx, const union mschapv2_challenge_hash *  chash, const union mschapv2_password_hash *  phash, struct mschapv2_nt_response *  nt  )

static

Calculate MS-CHAPv2 challenge response.

Parameters

ctx	Context block
chash	Challenge hash
phash	Password hash (after expansion)
nt	NT response to fill in

This is the ChallengeResponse() function as documented in RFC 2759 section 8.5.

Definition at line 232 of file mschapv2.c.

                                                                {
        struct cipher_algorithm *des = &des_algorithm;
        unsigned int i;
        int rc;

        /* Construct response.  The design of the algorithm here is
         * interesting, suggesting that an intern at Microsoft had
         * heard the phrase "Triple DES" and hazarded a blind guess at
         * what it might mean.
         */
        for ( i = 0 ; i < ( sizeof ( phash->des ) /
                            sizeof ( phash->des[0] ) ) ; i++ ) {
                rc = cipher_setkey ( des, ctx->des, phash->des[i],
                                     sizeof ( phash->des[i] ) );
                assert ( rc == 0 ); /* no failure mode exists */
                cipher_encrypt ( des, ctx->des, chash->des, nt->block[i],
                                 sizeof ( chash->des ) );
        }
        DBGC ( ctx, "MSCHAPv2 NT response:\n" );
        DBGC_HDA ( ctx, 0, nt, sizeof ( *nt ) );
}

References assert(), mschapv2_nt_response::block, cipher_encrypt, ctx, DBGC, DBGC_HDA, mschapv2_challenge_hash::des, mschapv2_password_hash::des, des_algorithm, nt, and rc.

Referenced by mschapv2_response().

mschapv2_response()

void mschapv2_response	(	const char *	username,
		const char *	password,
		const struct mschapv2_challenge *	challenge,
		const struct mschapv2_challenge *	peer,
		struct mschapv2_response *	response
	)

Calculate MS-CHAPv2 challenge response.

Parameters

username	User name (or NULL to use empty string)
password	Password (or NULL to use empty string)
challenge	Authenticator challenge
peer	Peer challenge
response	Challenge response to fill in

This is essentially the GenerateNTResponse() function as documented in RFC 2759 section 8.1.

Definition at line 269 of file mschapv2.c.

                                                              {
        union mschapv2_context ctx;
        union mschapv2_challenge_hash chash;
        union mschapv2_password_hash phash;

        /* Zero reserved fields */
        memset ( response, 0, sizeof ( *response ) );

        /* Copy peer challenge to response */
        memcpy ( &response->peer, peer, sizeof ( response->peer ) );

        /* Construct challenge hash */
        mschapv2_challenge_hash ( &ctx, challenge, peer, username, &chash );

        /* Construct expanded password hash */
        mschapv2_password_hash ( &ctx, password, &phash );
        mschapv2_expand_hash ( &ctx, &phash );

        /* Construct NT response */
        mschapv2_challenge_response ( &ctx, &chash, &phash, &response->nt );
        DBGC ( &ctx, "MSCHAPv2 challenge response:\n" );
        DBGC_HDA ( &ctx, 0, response, sizeof ( *response ) );
}

References ctx, DBGC, DBGC_HDA, memcpy(), memset(), mschapv2_challenge_hash(), mschapv2_challenge_response(), mschapv2_expand_hash(), mschapv2_password_hash(), mschapv2_response::nt, mschapv2_response::peer, and peer.

Referenced by eap_rx_mschapv2_request(), and mschapv2_okx().

mschapv2_auth()

void mschapv2_auth	(	const char *	username,
		const char *	password,
		const struct mschapv2_challenge *	challenge,
		const struct mschapv2_response *	response,
		struct mschapv2_auth *	auth
	)

Calculate MS-CHAPv2 authenticator response.

Parameters

username	User name (or NULL to use empty string)
password	Password (or NULL to use empty string)
challenge	Authenticator challenge
response	Challenge response
auth	Authenticator response to fill in

This is essentially the GenerateAuthenticatorResponse() function as documented in RFC 2759 section 8.7.

Definition at line 308 of file mschapv2.c.

                                                  {
        struct digest_algorithm *sha1 = &sha1_algorithm;
        union mschapv2_context ctx;
        union mschapv2_challenge_hash chash;
        union mschapv2_password_hash phash;
        char tmp[3];
        char *wtf;
        unsigned int i;

        /* Construct hash of password hash */
        mschapv2_password_hash ( &ctx, password, &phash );
        mschapv2_hash_hash ( &ctx, &phash );

        /* Construct unnamed intermediate hash */
        digest_init ( sha1, ctx.sha1 );
        digest_update ( sha1, ctx.sha1, phash.md4, sizeof ( phash.md4 ) );
        digest_update ( sha1, ctx.sha1, &response->nt,
                        sizeof ( response->nt ) );
        digest_update ( sha1, ctx.sha1, mschapv2_magic1,
                        sizeof ( mschapv2_magic1 ) );
        digest_final ( sha1, ctx.sha1, phash.sha1 );
        DBGC ( &ctx, "MSCHAPv2 NT response:\n" );
        DBGC_HDA ( &ctx, 0, &response->nt, sizeof ( response->nt ) );
        DBGC ( &ctx, "MSCHAPv2 unnamed intermediate hash:\n" );
        DBGC_HDA ( &ctx, 0, phash.sha1, sizeof ( phash.sha1 ) );

        /* Construct challenge hash */
        mschapv2_challenge_hash ( &ctx, challenge, &response->peer,
                                  username, &chash );

        /* Construct authenticator response hash */
        digest_init ( sha1, ctx.sha1 );
        digest_update ( sha1, ctx.sha1, phash.sha1, sizeof ( phash.sha1 ) );
        digest_update ( sha1, ctx.sha1, chash.des, sizeof ( chash.des ) );
        digest_update ( sha1, ctx.sha1, mschapv2_magic2,
                        sizeof ( mschapv2_magic2 ) );
        digest_final ( sha1, ctx.sha1, phash.sha1 );
        DBGC ( &ctx, "MSCHAPv2 authenticator response hash:\n" );
        DBGC_HDA ( &ctx, 0, phash.sha1, sizeof ( phash.sha1 ) );

        /* Encode authenticator response hash */
        wtf = auth->wtf;
        *(wtf++) = 'S';
        *(wtf++) = '=';
        DBGC ( &ctx, "MSCHAPv2 authenticator response: S=" );
        for ( i = 0 ; i < sizeof ( phash.sha1 ) ; i++ ) {
                snprintf ( tmp, sizeof ( tmp ), "%02X", phash.sha1[i] );
                *(wtf++) = tmp[0];
                *(wtf++) = tmp[1];
                DBGC ( &ctx, "%s", tmp );
        }
        DBGC ( &ctx, "\n" );
}

References auth, ctx, DBGC, DBGC_HDA, mschapv2_challenge_hash::des, mschapv2_password_hash::md4, mschapv2_challenge_hash(), mschapv2_hash_hash(), mschapv2_magic1, mschapv2_magic2, mschapv2_password_hash(), mschapv2_response::nt, mschapv2_response::peer, mschapv2_password_hash::sha1, sha1_algorithm, snprintf(), tmp, and wtf.

Referenced by mschapv2_okx().

Variable Documentation

mschapv2_magic1

const char mschapv2_magic1[39]

static

Initial value:

=
        "Magic server to client signing constant"

MS-CHAPv2 magic constant 1.

Definition at line 99 of file mschapv2.c.

Referenced by mschapv2_auth().

mschapv2_magic2

const char mschapv2_magic2[41]

static

Initial value:

=
        "Pad to make it do more than one iteration"

MS-CHAPv2 magic constant 2.

Definition at line 103 of file mschapv2.c.

Referenced by mschapv2_auth().