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//==========================================================================

//

//      ./lib/current/src/keytools.c

//

//

//==========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos 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 or (at your option) any later version.

//

// eCos 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 eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

//

// This exception does not invalidate any other reasons why a work based on

// this file might be covered by the GNU General Public License.

//

// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//####UCDSNMPCOPYRIGHTBEGIN####

//

// -------------------------------------------

//

// Portions of this software may have been derived from the UCD-SNMP

// project,  <http://ucd-snmp.ucdavis.edu/>  from the University of

// California at Davis, which was originally based on the Carnegie Mellon

// University SNMP implementation.  Portions of this software are therefore

// covered by the appropriate copyright disclaimers included herein.

//

// The release used was version 4.1.2 of May 2000.  "ucd-snmp-4.1.2"

// -------------------------------------------

//

//####UCDSNMPCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):    hmt

// Contributors: hmt

// Date:         2000-05-30

// Purpose:      Port of UCD-SNMP distribution to eCos.

// Description:  

//              

//

//####DESCRIPTIONEND####

//

//==========================================================================

/********************************************************************

       Copyright 1989, 1991, 1992 by Carnegie Mellon University

                          Derivative Work -

Copyright 1996, 1998, 1999, 2000 The Regents of the University of California

                         All Rights Reserved

Permission to use, copy, modify and distribute this software and its

documentation for any purpose and without fee is hereby granted,

provided that the above copyright notice appears in all copies and

that both that copyright notice and this permission notice appear in

supporting documentation, and that the name of CMU and The Regents of

the University of California not be used in advertising or publicity

pertaining to distribution of the software without specific written

permission.

CMU AND THE REGENTS OF THE UNIVERSITY OF CALIFORNIA DISCLAIM ALL

WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED

WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL CMU OR

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA BE LIABLE FOR ANY SPECIAL,

INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING

FROM THE LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF

CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN

CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

*********************************************************************/

/*

 * keytools.c

 */

#include <config.h>

#ifdef CYGPKG_SNMPAGENT_V3_SUPPORT

#include <stdio.h>

#include <sys/types.h>

#if HAVE_WINSOCK_H

#include <winsock.h>

#endif

#ifdef HAVE_NETINET_IN_H

#include <netinet/in.h>

#endif

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#if HAVE_STRING_H

#include <string.h>

#else

#include <strings.h>

#endif

#if HAVE_DMALLOC_H

#include <dmalloc.h>

#endif

#include "asn1.h"

#include "snmp_api.h"

#ifdef USE_OPENSSL

#       include <openssl/hmac.h>

#else 

#ifdef USE_INTERNAL_MD5

#include "md5.h"

#endif

#endif

#include "scapi.h"

#include "keytools.h"

#include "tools.h"

#include "snmp_debug.h"

#include "snmp_logging.h"

#include "transform_oids.h"

/*******************************************************************-o-******

 * generate_Ku

 *

 * Parameters:

 *      *hashtype       MIB OID for the transform type for hashing.

 *       hashtype_len   Length of OID value.

 *      *P              Pre-allocated bytes of passpharase.

 *       pplen          Length of passphrase.

 *      *Ku             Buffer to contain Ku.

 *      *kulen          Length of Ku buffer.

 *

 * Returns:

 *      SNMPERR_SUCCESS                 Success.

 *      SNMPERR_GENERR                  All errors.

 *

 *

 * Convert a passphrase into a master user key, Ku, according to the

 * algorithm given in RFC 2274 concerning the SNMPv3 User Security Model (USM)

 * as follows:

 *

 * Expand the passphrase to fill the passphrase buffer space, if necessary,

 * concatenation as many duplicates as possible of P to itself.  If P is

 * larger than the buffer space, truncate it to fit.

 *

 * Then hash the result with the given hashtype transform.  Return

 * the result as Ku.

 *

 * If successful, kulen contains the size of the hash written to Ku.

 *

 * NOTE  Passphrases less than USM_LENGTH_P_MIN characters in length

 *       cause an error to be returned.

 *       (Punt this check to the cmdline apps?  XXX)

 */

int

generate_Ku(    oid     *hashtype,      u_int  hashtype_len,

                u_char  *P,             size_t  pplen,

                u_char  *Ku,            size_t *kulen)

#if defined(USE_INTERNAL_MD5) || defined(USE_OPENSSL)

{

        int              rval   = SNMPERR_SUCCESS,

                         nbytes = USM_LENGTH_EXPANDED_PASSPHRASE;

        u_int            i, pindex = 0;

        u_char           buf[USM_LENGTH_KU_HASHBLOCK],

                        *bufp;

#ifdef USE_OPENSSL

        EVP_MD_CTX      *ctx = malloc(sizeof(EVP_MD_CTX));

#else

        MDstruct         MD;

#endif

        /*

         * Sanity check.

         */

        if ( !hashtype || !P || !Ku || !kulen

                || (*kulen<=0)

                || (hashtype_len != USM_LENGTH_OID_TRANSFORM) )

        {

                QUITFUN(SNMPERR_GENERR, generate_Ku_quit);

        }

        if (pplen < USM_LENGTH_P_MIN) {

#ifdef SNMP_TESTING_CODE

          snmp_log(LOG_WARNING, "Warning: passphrase chosen is below the length requiremnts of the USM.\n");

#else

          snmp_set_detail("Password length too short.");

          QUITFUN(SNMPERR_GENERR, generate_Ku_quit);

#endif

        }

        /*

         * Setup for the transform type.

         */

#ifdef USE_OPENSSL

        if (ISTRANSFORM(hashtype, HMACMD5Auth))

          EVP_DigestInit(ctx, EVP_md5());

        else if (ISTRANSFORM(hashtype, HMACSHA1Auth))

          EVP_DigestInit(ctx, EVP_sha1());

        else  {

          free(ctx);

          return (SNMPERR_GENERR);

        }

#else 

        MDbegin(&MD);

#endif /* USE_OPENSSL */

        while (nbytes > 0) {

                bufp = buf;

                for (i = 0; i < USM_LENGTH_KU_HASHBLOCK; i++) {

                        *bufp++ = P[pindex++ % pplen];

                }

#ifdef USE_OPENSSL

                EVP_DigestUpdate(ctx, buf, USM_LENGTH_KU_HASHBLOCK);

#else

                if (MDupdate(&MD, buf, USM_LENGTH_KU_HASHBLOCK*8)) {

                    rval = SNMPERR_USM_ENCRYPTIONERROR;

                    goto md5_fin;

                }

#endif /* USE_OPENSSL */

                nbytes -= USM_LENGTH_KU_HASHBLOCK;

        }

#ifdef USE_OPENSSL

        EVP_DigestFinal(ctx, (unsigned char *) Ku, (unsigned int *) kulen);

        /* what about free() */

#else

        if (MDupdate(&MD, buf, 0)) {

            rval = SNMPERR_USM_ENCRYPTIONERROR;

            goto md5_fin;

        }

        *kulen = sc_get_properlength(hashtype, hashtype_len);

        MDget(&MD, Ku, *kulen);

md5_fin:

        memset(&MD, 0, sizeof(MD));

#endif /* USE_OPENSSL */

#ifdef SNMP_TESTING_CODE

        DEBUGMSGTL(("generate_Ku", "generating Ku (from %s): ", P));

        for(i=0; i < *kulen; i++)

          DEBUGMSG(("generate_Ku", "%02x",Ku[i]));

        DEBUGMSG(("generate_Ku","\n"));

#endif /* SNMP_TESTING_CODE */

generate_Ku_quit:

        memset(buf, 0, sizeof(buf));

#ifdef USE_OPENSSL

        free(ctx);

#endif

        return rval;

}  /* end generate_Ku() */

#else

_KEYTOOLS_NOT_AVAILABLE

#endif                                          /* internal or openssl */

/*******************************************************************-o-******

 * generate_kul

 *

 * Parameters:

 *      *hashtype

 *       hashtype_len

 *      *engineID

 *       engineID_len

 *      *Ku             Master key for a given user.

 *       ku_len         Length of Ku in bytes.

 *      *Kul            Localized key for a given user at engineID.

 *      *kul_len        Length of Kul buffer (IN); Length of Kul key (OUT).

 *

 * Returns:

 *      SNMPERR_SUCCESS                 Success.

 *      SNMPERR_GENERR                  All errors.

 *

 *

 * Ku MUST be the proper length (currently fixed) for the given hashtype.

 *

 * Upon successful return, Kul contains the localized form of Ku at

 * engineID, and the length of the key is stored in kul_len.

 *

 * The localized key method is defined in RFC2274, Sections 2.6 and A.2, and

 * originally documented in:

 *      U. Blumenthal, N. C. Hien, B. Wijnen,

 *      "Key Derivation for Network Management Applications",

 *      IEEE Network Magazine, April/May issue, 1997.

 *

 *

 * ASSUMES  SNMP_MAXBUF >= sizeof(Ku + engineID + Ku).

 *

 * NOTE  Localized keys for privacy transforms are generated via

 *       the authentication transform held by the same usmUser.

 *

 * XXX  An engineID of any length is accepted, even if larger than

 *      what is spec'ed for the textual convention.

 */

int

generate_kul(   oid     *hashtype,      u_int  hashtype_len,

                u_char  *engineID,      size_t  engineID_len,

                u_char  *Ku,            size_t  ku_len,

                u_char  *Kul,           size_t *kul_len)

#if defined(USE_OPENSSL) || defined(USE_INTERNAL_MD5)

{

        int              rval    = SNMPERR_SUCCESS;

        u_int            nbytes  = 0;

        size_t           properlength;

        u_char           buf[SNMP_MAXBUF];

        void            *context = NULL;

#ifdef SNMP_TESTING_CODE

        int              i;

#endif

        /*

         * Sanity check.

         */

        if ( !hashtype || !engineID || !Ku || !Kul || !kul_len

                || (engineID_len<=0) || (ku_len<=0) || (*kul_len<=0)

                || (hashtype_len != USM_LENGTH_OID_TRANSFORM) )

        {

                QUITFUN(SNMPERR_GENERR, generate_kul_quit);

        }

        properlength = sc_get_properlength(hashtype, hashtype_len);

        if (properlength == SNMPERR_GENERR)

          QUITFUN(SNMPERR_GENERR, generate_kul_quit);

        if (((int)*kul_len < properlength) || ((int)ku_len < properlength) ) {

                QUITFUN(SNMPERR_GENERR, generate_kul_quit);

        }

        /*

         * Concatenate Ku and engineID properly, then hash the result.

         * Store it in Kul.

         */

        nbytes = 0;

        memcpy(buf,        Ku,          properlength); nbytes += properlength;

        memcpy(buf+nbytes, engineID,    engineID_len); nbytes += engineID_len;

        memcpy(buf+nbytes, Ku,          properlength); nbytes += properlength;

        rval = sc_hash(hashtype, hashtype_len, buf, nbytes, Kul, kul_len);

#ifdef SNMP_TESTING_CODE

        DEBUGMSGTL(("generate_kul", "generating Kul (from Ku): "));

        for(i=0; i < *kul_len; i++)

          DEBUGMSG(("generate_kul", "%02x",Kul[i]));

        DEBUGMSG(("generate_kul", "keytools\n"));

#endif /* SNMP_TESTING_CODE */

        QUITFUN(rval, generate_kul_quit);

generate_kul_quit:

        SNMP_FREE(context);

        return rval;

}  /* end generate_kul() */

#else

_KEYTOOLS_NOT_AVAILABLE

#endif                                          /* internal or openssl */

/*******************************************************************-o-******

 * encode_keychange

 *

 * Parameters:

 *      *hashtype       MIB OID for the hash transform type.

 *       hashtype_len   Length of the MIB OID hash transform type.

 *      *oldkey         Old key that is used to encodes the new key.

 *       oldkey_len     Length of oldkey in bytes.

 *      *newkey         New key that is encoded using the old key.

 *       newkey_len     Length of new key in bytes.

 *      *kcstring       Buffer to contain the KeyChange TC string.

 *      *kcstring_len   Length of kcstring buffer.

 *

 * Returns:

 *      SNMPERR_SUCCESS                 Success.

 *      SNMPERR_GENERR                  All errors.

 *

 *

 * Uses oldkey and acquired random bytes to encode newkey into kcstring

 * according to the rules of the KeyChange TC described in RFC 2274, Section 5.

 *

 * Upon successful return, *kcstring_len contains the length of the

 * encoded string.

 *

 * ASSUMES      Old and new key are always equal to each other, although

 *              this may be less than the transform type hash output

 *              output length (eg, using KeyChange for a DESPriv key when

 *              the user also uses SHA1Auth).  This also implies that the

 *              hash placed in the second 1/2 of the key change string

 *              will be truncated before the XOR'ing when the hash output is

 *              larger than that 1/2 of the key change string.

 *

 *              *kcstring_len will be returned as exactly twice that same

 *              length though the input buffer may be larger.

 *

 * XXX FIX:     Does not handle varibable length keys.

 * XXX FIX:     Does not handle keys larger than the hash algorithm used.

 */

int

encode_keychange(       oid     *hashtype,      u_int  hashtype_len,

                        u_char  *oldkey,        size_t  oldkey_len,

                        u_char  *newkey,        size_t  newkey_len,

                        u_char  *kcstring,      size_t *kcstring_len)

#if defined(USE_OPENSSL) || defined(USE_INTERNAL_MD5)

{

        int              rval    = SNMPERR_SUCCESS;

        size_t           properlength;

        size_t            nbytes  = 0;

        u_char          *tmpbuf = NULL;

        void            *context = NULL;

        /*

         * Sanity check.

         */

        if ( !hashtype || !oldkey || !newkey || !kcstring || !kcstring_len

                || (oldkey_len<=0) || (newkey_len<=0) || (*kcstring_len<=0)

                || (hashtype_len != USM_LENGTH_OID_TRANSFORM) )

        {

                QUITFUN(SNMPERR_GENERR, encode_keychange_quit);

        }

        /*

         * Setup for the transform type.

         */

        properlength = sc_get_properlength(hashtype, hashtype_len);

        if (properlength == SNMPERR_GENERR)

          QUITFUN(SNMPERR_GENERR, encode_keychange_quit);

        if ( (oldkey_len != newkey_len) || (*kcstring_len < (2*oldkey_len)) )

        {

                QUITFUN(SNMPERR_GENERR, encode_keychange_quit);

        }

        properlength = SNMP_MIN((int)oldkey_len, properlength);

        /*

         * Use the old key and some random bytes to encode the new key

         * in the KeyChange TC format:

         *      . Get random bytes (store in first half of kcstring),

         *      . Hash (oldkey | random_bytes) (into second half of kcstring),

         *      . XOR hash and newkey (into second half of kcstring).

         *

         * Getting the wrong number of random bytes is considered an error.

         */

        nbytes = properlength;

#if defined(SNMP_TESTING_CODE) && defined(RANDOMZEROS)

                memset(kcstring, 0, nbytes);

                DEBUGMSG(("encode_keychange",

                          "** Using all zero bits for \"random\" delta of )"

                          "the keychange string! **\n"));

#else /* !SNMP_TESTING_CODE */

                rval = sc_random(kcstring, &nbytes);

                QUITFUN(rval, encode_keychange_quit);

                if ((int)nbytes != properlength) {

                        QUITFUN(SNMPERR_GENERR, encode_keychange_quit);

                }

#endif /* !SNMP_TESTING_CODE */

        tmpbuf = (u_char *)malloc(properlength*2);

        if (tmpbuf) {

            memcpy(tmpbuf, oldkey, properlength);

            memcpy(tmpbuf+properlength, kcstring, properlength);

            *kcstring_len -= properlength;

            rval = sc_hash(hashtype, hashtype_len, tmpbuf, properlength*2,

                           kcstring+properlength, kcstring_len);

            QUITFUN(rval, encode_keychange_quit);

            *kcstring_len = (properlength*2);

            kcstring += properlength;

            nbytes    = 0;

            while ((int)(nbytes++) < properlength) {

                u_char kcs = *kcstring;

                *kcstring++ = kcs ^ *newkey++;

            }

        }

encode_keychange_quit:

        if (rval != SNMPERR_SUCCESS) memset(kcstring, 0, *kcstring_len);

        SNMP_FREE(tmpbuf);

        SNMP_FREE(context);

        return rval;

}  /* end encode_keychange() */

#else

_KEYTOOLS_NOT_AVAILABLE

#endif                                          /* internal or openssl */

/*******************************************************************-o-******

 * decode_keychange

 *

 * Parameters:

 *      *hashtype       MIB OID of the hash transform to use.

 *       hashtype_len   Length of the hash transform MIB OID.

 *      *oldkey         Old key that is used to encode the new key.

 *       oldkey_len     Length of oldkey in bytes.

 *      *kcstring       Encoded KeyString buffer containing the new key.

 *       kcstring_len   Length of kcstring in bytes.

 *      *newkey         Buffer to hold the extracted new key.

 *      *newkey_len     Length of newkey in bytes.

 *

 * Returns:

 *      SNMPERR_SUCCESS                 Success.

 *      SNMPERR_GENERR                  All errors.

 *

 *

 * Decodes a string of bits encoded according to the KeyChange TC described

 * in RFC 2274, Section 5.  The new key is extracted from *kcstring with

 * the aid of the old key.

 *

 * Upon successful return, *newkey_len contains the length of the new key.

 *

 *

 * ASSUMES      Old key is exactly 1/2 the length of the KeyChange buffer,

 *              although this length may be less than the hash transform

 *              output.  Thus the new key length will be equal to the old

 *              key length.

 */

/* XXX:  if the newkey is not long enough, it should be freed and remalloced */

int

decode_keychange(       oid     *hashtype,      u_int  hashtype_len,

                        u_char  *oldkey,        size_t  oldkey_len,

                        u_char  *kcstring,      size_t  kcstring_len,

                        u_char  *newkey,        size_t *newkey_len)

#if defined(USE_OPENSSL) || defined(USE_INTERNAL_MD5)

{

        int              rval    = SNMPERR_SUCCESS;

        size_t           properlength = 0;

        u_int            nbytes  = 0;

        u_char          *bufp,

                         tmp_buf[SNMP_MAXBUF];

        size_t           tmp_buf_len = SNMP_MAXBUF;

        void            *context = NULL;

        u_char          *tmpbuf = NULL;

        /*

         * Sanity check.

         */

        if ( !hashtype || !oldkey || !kcstring || !newkey || !newkey_len

                || (oldkey_len<=0) || (kcstring_len<=0) || (*newkey_len<=0)

                || (hashtype_len != USM_LENGTH_OID_TRANSFORM) )

        {

                QUITFUN(SNMPERR_GENERR, decode_keychange_quit);

        }

        /*

         * Setup for the transform type.

         */

        properlength = sc_get_properlength(hashtype, hashtype_len);

        if (properlength == SNMPERR_GENERR)

          QUITFUN(SNMPERR_GENERR, decode_keychange_quit);

        if ( ((oldkey_len*2) != kcstring_len) || (*newkey_len < oldkey_len) )

        {

                QUITFUN(SNMPERR_GENERR, decode_keychange_quit);

        }

        properlength = oldkey_len;

        *newkey_len = properlength;

        /*

         * Use the old key and the given KeyChange TC string to recover

         * the new key:

         *      . Hash (oldkey | random_bytes) (into newkey),

         *      . XOR hash and encoded (second) half of kcstring (into newkey).

         */

        tmpbuf = (u_char *)malloc(properlength*2);

        if (tmpbuf) {

            memcpy(tmpbuf, oldkey, properlength);

            memcpy(tmpbuf+properlength, kcstring, properlength);

            rval = sc_hash(hashtype, hashtype_len, tmpbuf, properlength*2,

                           tmp_buf, &tmp_buf_len);

            QUITFUN(rval, decode_keychange_quit);

            memcpy(newkey, tmp_buf, properlength);

            bufp   = kcstring+properlength;

            nbytes = 0;

            while ((int)(nbytes++) < properlength) {

                    u_char nk = *newkey;

                    *newkey++ = nk ^ *bufp++;

            }

        }

decode_keychange_quit:

        if (rval != SNMPERR_SUCCESS) {

                memset(newkey, 0, properlength);

        }

        memset(tmp_buf, 0, SNMP_MAXBUF);

        SNMP_FREE(context);

        if (tmpbuf != NULL) SNMP_FREE(tmpbuf);

        return rval;

}  /* end decode_keychange() */

#else

_KEYTOOLS_NOT_AVAILABLE

#endif                                          /* internal or openssl */

#endif /* CYGPKG_SNMPAGENT_V3_SUPPORT */