🚀 go-pugleaf

In testing the interoperability of Kerberos between two different
machine architectures (NCR Tower 650 (M68020) and NCR 3300 (i486)).
I have noticed an incompatibility in the safe message interface.

The problem is due to the different byte order of the two machines.
krb_mk_safe() and krb_rd_safe() use the des_quad_cksum() function
to generate a 16 byte checksum.  krb_rd_safe() uses the macro
swap_u_16 on the received checksum (if necessary) before comparing
it to the calculated checksum.  However, this macro reverses the
order of the entire 16 bytes, when actually each of the 4 longs
that are stuffed into the 16 byte checksum need to be swapped.

One solution is to resolve the byte order in the des_quad_cksum()
routine since the result is always used as a byte string.
I.e. make the byte order of the 16 byte checksum produced by quad_cksum()
machine independent.  Note, des_quad_cksum() still returns a long in host
byte order.  This would also eliminate the swap_u_16 macro in krb_rd_req().

Has this problem already been solved? (I am using version 4.9)
If not, is this solution correct, or should the byte order be fixed
in krb_rd_safe() by using a different macro or function?

Here is a diff of the solution described above.
------------------------------------------------
*** oquad_cksum.c	Fri Mar 22 17:08:42 1991
--- quad_cksum.c	Fri Mar 22 17:06:16 1991
***************
*** 122,127 ****
--- 122,129 ----
       * checksum is written unto the address pointed to.
       */
  
+     unsigned long zz;
+     unsigned long zz2;
      register unsigned long z;
      register unsigned long z2;
      register unsigned long x;
***************
*** 159,166 ****
  	}
  
  	if (out != NULL) {
! 	    *out++ = z;
! 	    *out++ = z2;
  	}
      }
      /* return final z value as 32 bit version of checksum */
--- 161,170 ----
  	}
  
  	if (out != NULL) {
! 	    zz = z;
! 	    zz2 = z2;
! 	    *out++ = vaxtohl(&zz);
! 	    *out++ = vaxtohl(&zz2);
  	}
      }
      /* return final z value as 32 bit version of checksum */
*** ord_safe.c	Fri Mar 22 17:10:10 1991
--- rd_safe.c	Fri Mar 22 17:10:04 1991
***************
*** 165,171 ****
       */
  
      bcopy((char *)p,(char *)big_cksum,sizeof(big_cksum));
-     if (swap_bytes) swap_u_16(big_cksum);
  
  #ifdef NOENCRYPTION
      bzero(calc_cksum, sizeof(calc_cksum));
--- 165,170 ----

---------------------------------------------------------------------------

Jack Dundon
NCR E&M San Diego
(619)485-3397