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/*
* lib/krb4/mk_priv.c
*
* Copyright 1986, 1987, 1988, 2000 by the Massachusetts Institute of
* Technology. 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 M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* This routine constructs a Kerberos 'private msg', i.e.
* cryptographically sealed with a private session key.
*
* Returns either < 0 ===> error, or resulting size of message
*
* Steve Miller Project Athena MIT/DEC
*/
#include <stdio.h>
#include <string.h>
#define DEFINE_SOCKADDR /* Ask for sockets declarations from krb.h. */
#include "krb.h"
#include "prot.h"
#include "des.h"
#include "lsb_addr_cmp.h"
extern int krb_debug;
/*
* krb_mk_priv() constructs an AUTH_MSG_PRIVATE message. It takes
* some user data "in" of "length" bytes and creates a packet in "out"
* consisting of the user data, a timestamp, and the sender's network
* address.
#ifndef NOENCRYTION
* The packet is encrypted by pcbc_encrypt(), using the given
* "key" and "schedule".
#endif
* The length of the resulting packet "out" is
* returned.
*
* It is similar to krb_mk_safe() except for the additional key
* schedule argument "schedule" and the fact that the data is encrypted
* rather than appended with a checksum. Also, the protocol version
* number is "private_msg_ver", defined in krb_rd_priv.c, rather than
* KRB_PROT_VERSION, defined in "krb.h".
*
* The "out" packet consists of:
*
* Size Variable Field
* ---- -------- -----
*
* 1 byte private_msg_ver protocol version number
* 1 byte AUTH_MSG_PRIVATE | message type plus local
* HOST_BYTE_ORDER byte order in low bit
*
#ifdef NOENCRYPTION
* 4 bytes c_length length of data
#else
* 4 bytes c_length length of encrypted data
*
* ===================== begin encrypt ================================
#endif
*
* 4 bytes length length of user data
* length in user data
* 1 byte msg_time_5ms timestamp milliseconds
* 4 bytes sender->sin.addr.s_addr sender's IP address
*
* 4 bytes msg_time_sec or timestamp seconds with
* -msg_time_sec direction in sign bit
*
* 0<=n<=7 bytes pad to 8 byte multiple zeroes
#ifndef NOENCRYPTION
* (done by pcbc_encrypt())
*
* ======================= end encrypt ================================
#endif
*/
long KRB5_CALLCONV
krb_mk_priv(in, out, length, schedule, key, sender, receiver)
u_char *in; /* application data */
u_char *out; /* put msg here, leave room for
* header! breaks if in and out
* (header stuff) overlap */
unsigned KRB4_32 length; /* of in data */
Key_schedule schedule; /* precomputed key schedule */
C_Block *key; /* encryption key for seed and ivec */
struct sockaddr_in *sender; /* sender address */
struct sockaddr_in *receiver; /* receiver address */
{
register u_char *p,*q;
u_char *c_length_ptr;
extern int private_msg_ver; /* in krb_rd_priv.c */
unsigned KRB4_32 c_length, c_length_raw;
u_char msg_time_5ms;
unsigned KRB4_32 msg_time_sec;
unsigned KRB4_32 msg_time_usec;
/* Be really paranoid. */
if (sizeof(sender->sin_addr.s_addr) != 4)
return -1;
/*
* get the current time to use instead of a sequence #, since
* process lifetime may be shorter than the lifetime of a session
* key.
*/
msg_time_sec = TIME_GMT_UNIXSEC_US(&msg_time_usec);
msg_time_5ms = msg_time_usec / 5000; /* 5ms quanta */
p = out;
/* Cruftiness below! */
*p++ = private_msg_ver ? private_msg_ver : KRB_PROT_VERSION;
*p++ = AUTH_MSG_PRIVATE;
/* save ptr to cipher length */
c_length_ptr = p;
p += 4;
#ifndef NOENCRYPTION
/* start for encrypted stuff */
#endif
q = p;
/* stuff input length */
KRB4_PUT32BE(p, length);
#ifdef NOENCRYPTION
/* make all the stuff contiguous for checksum */
#else
/* make all the stuff contiguous for checksum and encryption */
#endif
memcpy(p, in, (size_t)length);
p += length;
/* stuff time 5ms */
*p++ = msg_time_5ms;
/* stuff source address */
memcpy(p, &sender->sin_addr.s_addr,
sizeof(sender->sin_addr.s_addr));
p += sizeof(sender->sin_addr.s_addr);
/*
* direction bit is the sign bit of the timestamp. Ok
* until 2038??
*/
/* For compatibility with broken old code, compares are done in VAX
byte order (LSBFIRST) */
if (lsb_net_ulong_less(sender->sin_addr.s_addr, /* src < recv */
receiver->sin_addr.s_addr) == -1)
msg_time_sec = -msg_time_sec;
else if (lsb_net_ulong_less(sender->sin_addr.s_addr,
receiver->sin_addr.s_addr) == 0)
if (lsb_net_ushort_less(sender->sin_port,
receiver->sin_port) == -1)
msg_time_sec = -msg_time_sec;
/* stuff time sec */
KRB4_PUT32BE(p, msg_time_sec);
/*
* All that for one tiny bit! Heaven help those that talk to
* themselves.
*/
#ifdef notdef
/*
* calculate the checksum of the length, address, sequence, and
* inp data
*/
cksum = quad_cksum(q,NULL,p-q,0,key);
DEB (("\ncksum = %u",cksum));
/* stuff checksum */
memcpy(p, &cksum, sizeof(cksum));
p += sizeof(cksum);
#endif
#ifdef NOENCRYPTION
/*
* All the data have been assembled, compute length
*/
#else
/*
* All the data have been assembled, compute length and encrypt
* starting with the length, data, and timestamps use the key as
* an ivec.
*/
#endif
c_length_raw = p - q;
c_length = ((c_length_raw + sizeof(C_Block) -1)
/ sizeof(C_Block)) * sizeof(C_Block);
/* stuff the length */
p = c_length_ptr;
KRB4_PUT32BE(p, c_length);
#ifndef NOENCRYPTION
/* pcbc encrypt, pad as needed, use key as ivec */
pcbc_encrypt((C_Block *)q,(C_Block *)q, (long)c_length_raw,
schedule, key, ENCRYPT);
#endif /* NOENCRYPTION */
return q - out + c_length; /* resulting size */
}
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