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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 "des_int.h"
#include "rsa-md4.h"
#include "keyhash_provider.h"
#define CONFLENGTH 8
/* Force acceptance of krb5-beta5 md4des checksum for now. */
#define KRB5_MD4DES_BETA5_COMPAT
static const mit_des_cblock mit_des_zeroblock[8] /* = all zero */;
static void
k5_md4des_hash_size(size_t *output)
{
*output = CONFLENGTH+RSA_MD4_CKSUM_LENGTH;
}
/* des-cbc(xorkey, conf | rsa-md4(conf | data)) */
/* this could be done in terms of the md4 and des providers, but
that's less efficient, and there's no need for this to be generic */
static krb5_error_code
k5_md4des_hash(const krb5_keyblock *key, krb5_keyusage usage, const krb5_data *ivec,
const krb5_data *input, krb5_data *output)
{
krb5_error_code ret;
krb5_data data;
krb5_MD4_CTX ctx;
unsigned char conf[CONFLENGTH];
unsigned char xorkey[8];
int i;
mit_des_key_schedule schedule;
if (key->length != 8)
return(KRB5_BAD_KEYSIZE);
if (ivec)
return(KRB5_CRYPTO_INTERNAL);
if (output->length != (CONFLENGTH+RSA_MD4_CKSUM_LENGTH))
return(KRB5_CRYPTO_INTERNAL);
/* create the confouder */
data.length = CONFLENGTH;
data.data = (char *) conf;
if ((ret = krb5_c_random_make_octets(/* XXX */ 0, &data)))
return(ret);
/* create and schedule the encryption key */
memcpy(xorkey, key->contents, sizeof(xorkey));
for (i=0; i<sizeof(xorkey); i++)
xorkey[i] ^= 0xf0;
switch (ret = mit_des_key_sched(xorkey, schedule)) {
case -1:
return(KRB5DES_BAD_KEYPAR);
case -2:
return(KRB5DES_WEAK_KEY);
}
/* hash the confounder, then the input data */
krb5_MD4Init(&ctx);
krb5_MD4Update(&ctx, conf, CONFLENGTH);
krb5_MD4Update(&ctx, (unsigned char *) input->data,
(unsigned int) input->length);
krb5_MD4Final(&ctx);
/* construct the buffer to be encrypted */
memcpy(output->data, conf, CONFLENGTH);
memcpy(output->data+CONFLENGTH, ctx.digest, RSA_MD4_CKSUM_LENGTH);
/* encrypt it, in place. this has a return value, but it's
always zero. */
mit_des_cbc_encrypt((krb5_pointer) output->data,
(krb5_pointer) output->data, output->length,
schedule, (unsigned char *) mit_des_zeroblock, 1);
return(0);
}
static krb5_error_code
k5_md4des_verify(const krb5_keyblock *key, krb5_keyusage usage,
const krb5_data *ivec,
const krb5_data *input, const krb5_data *hash,
krb5_boolean *valid)
{
krb5_MD4_CTX ctx;
unsigned char plaintext[CONFLENGTH+RSA_MD4_CKSUM_LENGTH];
unsigned char xorkey[8];
int i;
mit_des_key_schedule schedule;
int compathash = 0;
if (key->length != 8)
return(KRB5_BAD_KEYSIZE);
if (ivec)
return(KRB5_CRYPTO_INTERNAL);
if (hash->length != (CONFLENGTH+RSA_MD4_CKSUM_LENGTH)) {
#ifdef KRB5_MD4DES_BETA5_COMPAT
if (hash->length != RSA_MD4_CKSUM_LENGTH)
return(KRB5_CRYPTO_INTERNAL);
else
compathash = 1;
#else
return(KRB5_CRYPTO_INTERNAL);
#endif
return(KRB5_CRYPTO_INTERNAL);
}
/* create and schedule the encryption key */
memcpy(xorkey, key->contents, sizeof(xorkey));
if (!compathash) {
for (i=0; i<sizeof(xorkey); i++)
xorkey[i] ^= 0xf0;
}
switch (mit_des_key_sched(xorkey, schedule)) {
case -1:
return(KRB5DES_BAD_KEYPAR);
case -2:
return(KRB5DES_WEAK_KEY);
}
/* decrypt it. this has a return value, but it's always zero. */
if (!compathash) {
mit_des_cbc_encrypt((krb5_pointer) hash->data,
(krb5_pointer) plaintext, hash->length,
schedule, (unsigned char *) mit_des_zeroblock, 0);
} else {
mit_des_cbc_encrypt((krb5_pointer) hash->data,
(krb5_pointer) plaintext, hash->length,
schedule, xorkey, 0);
}
/* hash the confounder, then the input data */
krb5_MD4Init(&ctx);
if (!compathash) {
krb5_MD4Update(&ctx, plaintext, CONFLENGTH);
}
krb5_MD4Update(&ctx, (unsigned char *) input->data,
(unsigned int) input->length);
krb5_MD4Final(&ctx);
/* compare the decrypted hash to the computed one */
if (!compathash) {
*valid =
(memcmp(plaintext+CONFLENGTH, ctx.digest, RSA_MD4_CKSUM_LENGTH)
== 0);
} else {
*valid =
(memcmp(plaintext, ctx.digest, RSA_MD4_CKSUM_LENGTH) == 0);
}
memset(plaintext, 0, sizeof(plaintext));
return(0);
}
const struct krb5_keyhash_provider krb5int_keyhash_md4des = {
k5_md4des_hash_size,
k5_md4des_hash,
k5_md4des_verify
};
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