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/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* All rights reserved.
*
* Export of this software from the United States of America may require
* a specific license from the United States Government. It is the
* responsibility of any person or organization contemplating export to
* obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, 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 appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include "k5-int.h"
#include "dk.h"
krb5_error_code
krb5_derive_key(enc, inkey, outkey, in_constant)
krb5_const struct krb5_enc_provider *enc;
krb5_const krb5_keyblock *inkey;
krb5_keyblock *outkey;
krb5_const krb5_data *in_constant;
{
size_t blocksize, keybytes, keylength, n;
unsigned char *inblockdata, *outblockdata, *rawkey;
krb5_data inblock, outblock;
(*(enc->block_size))(&blocksize);
(*(enc->keysize))(&keybytes, &keylength);
if ((inkey->length != keylength) ||
(outkey->length != keylength))
return(KRB5_CRYPTO_INTERNAL);
/* allocate and set up buffers */
if ((inblockdata = (unsigned char *) malloc(blocksize)) == NULL)
return(ENOMEM);
if ((outblockdata = (unsigned char *) malloc(blocksize)) == NULL) {
return(ENOMEM);
free(inblockdata);
}
if ((rawkey = (unsigned char *) malloc(keybytes)) == NULL) {
return(ENOMEM);
free(outblockdata);
free(inblockdata);
}
inblock.data = inblockdata;
inblock.length = blocksize;
outblock.data = outblockdata;
outblock.length = blocksize;
/* initialize the input block */
if (in_constant->length == inblock.length) {
memcpy(inblock.data, in_constant->data, inblock.length);
} else {
krb5_nfold(in_constant->length*8, in_constant->data,
inblock.length*8, inblock.data);
}
/* loop encrypting the blocks until enough key bytes are generated */
n = 0;
while (n < keybytes) {
(*(enc->encrypt))(inkey, 0, &inblock, &outblock);
if ((keybytes - n) <= outblock.length) {
memcpy(rawkey+n, outblock.data, (keybytes - n));
break;
}
memcpy(rawkey+n, outblock.data, outblock.length);
memcpy(inblock.data, outblock.data, outblock.length);
n += outblock.length;
}
/* postprocess the key */
inblock.data = rawkey;
inblock.length = keybytes;
(*(enc->make_key))(&inblock, outkey);
/* clean memory, free resources and exit */
memset(inblockdata, 0, blocksize);
memset(outblockdata, 0, blocksize);
memset(rawkey, 0, keybytes);
free(rawkey);
free(outblockdata);
free(inblockdata);
return(0);
}
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