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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* 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 KRB5int_MD4DES_BETA5_COMPAT
/* des-cbc(xorkey, conf | rsa-md4(conf | data)) */
extern struct krb5_enc_provider krb5int_enc_des;
/* Derive a key by XOR with 0xF0 bytes. */
static krb5_error_code
mk_xorkey(krb5_key origkey, krb5_key *xorkey)
{
krb5_error_code retval = 0;
unsigned char xorbytes[8];
krb5_keyblock xorkeyblock;
size_t i = 0;
if (origkey->keyblock.length != sizeof(xorbytes))
return KRB5_CRYPTO_INTERNAL;
memcpy(xorbytes, origkey->keyblock.contents, sizeof(xorbytes));
for (i = 0; i < sizeof(xorbytes); i++)
xorbytes[i] ^= 0xf0;
/* Do a shallow copy here. */
xorkeyblock = origkey->keyblock;
xorkeyblock.contents = xorbytes;
retval = krb5_k_create_key(0, &xorkeyblock, xorkey);
zap(xorbytes, sizeof(xorbytes));
return retval;
}
static krb5_error_code
k5_md4des_hash(krb5_key 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];
krb5_key xorkey = NULL;
struct krb5_enc_provider *enc = &krb5int_enc_des;
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);
ret = mk_xorkey(key, &xorkey);
if (ret)
return ret;
/* hash the confounder, then the input data */
krb5int_MD4Init(&ctx);
krb5int_MD4Update(&ctx, conf, CONFLENGTH);
krb5int_MD4Update(&ctx, (unsigned char *) input->data,
(unsigned int) input->length);
krb5int_MD4Final(&ctx);
/* construct the buffer to be encrypted */
memcpy(output->data, conf, CONFLENGTH);
memcpy(output->data+CONFLENGTH, ctx.digest, RSA_MD4_CKSUM_LENGTH);
ret = enc->encrypt(xorkey, NULL, output, output);
krb5_k_free_key(NULL, xorkey);
return (ret);
}
static krb5_error_code
k5_md4des_verify(krb5_key key, krb5_keyusage usage,
const krb5_data *ivec,
const krb5_data *input, const krb5_data *hash,
krb5_boolean *valid)
{
krb5_error_code ret;
krb5_MD4_CTX ctx;
unsigned char plaintext[CONFLENGTH+RSA_MD4_CKSUM_LENGTH];
krb5_key xorkey = NULL;
int compathash = 0;
struct krb5_enc_provider *enc = &krb5int_enc_des;
krb5_data output, iv;
iv.data = NULL;
iv.length = 0;
if (key->keyblock.length != 8)
return(KRB5_BAD_KEYSIZE);
if (hash->length != (CONFLENGTH+RSA_MD4_CKSUM_LENGTH)) {
#ifdef KRB5int_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);
}
if (compathash) {
iv.data = malloc(key->keyblock.length);
if (!iv.data) return ENOMEM;
iv.length = key->keyblock.length;
if (key->keyblock.contents)
memcpy(iv.data, key->keyblock.contents, key->keyblock.length);
} else {
ret = mk_xorkey(key, &xorkey);
if (ret)
return ret;
}
/* decrypt it */
output.data = (char *)plaintext;
output.length = hash->length;
if (!compathash) {
ret = enc->decrypt(xorkey, NULL, hash, &output);
krb5_k_free_key(NULL, xorkey);
} else {
ret = enc->decrypt(key, &iv, hash, &output);
zap(iv.data, iv.length);
free(iv.data);
}
if (ret) return(ret);
if (output.length > CONFLENGTH+RSA_MD4_CKSUM_LENGTH)
return KRB5_CRYPTO_INTERNAL;
/* hash the confounder, then the input data */
krb5int_MD4Init(&ctx);
if (!compathash) {
krb5int_MD4Update(&ctx, plaintext, CONFLENGTH);
}
krb5int_MD4Update(&ctx, (unsigned char *) input->data,
(unsigned int) input->length);
krb5int_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 = {
CONFLENGTH+RSA_MD4_CKSUM_LENGTH,
k5_md4des_hash,
k5_md4des_verify,
NULL,
NULL
};
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