MI a good use for encryption?

You might find this sample useful.  It was originally supplied by Bruce
Vining of the Rochester Lab.

It uses prototypes for the MI functions and also deals with EBCDIC/ASCII
issues.



      * Sample RPG code which takes into consideration the EBCDIC
      *   to ASCII conversion, the hash generation, and the creation of a
      *   suitable text string.  The program assumes that EBCDIC means CCSID
37
      *   and ASCII CCSID 819.  These assumptions may not hold true for all
      *   languages.

      * Courtesy Bruce Vining via Midrange-L (June 27 2000)

     H DFTACTGRP(*NO) ACTGRP('QILE') BNDDIR('QC2LE')
     D Cipher          PR                  EXTPROC('_CIPHER')
     D                                 *   VALUE
     D                                 *   VALUE
     D                                 *   VALUE

     D Convert         PR                  EXTPROC('_XLATEB')
     D                                 *   VALUE
     D                                 *   VALUE
     D                               10u 0 VALUE

     D cvthc           PR                  EXTPROC('cvthc')
     D                                1
     D                                1
     D                               10i 0 VALUE

     D Controls        DS
     D  Function                      5i 0 inz(5)
     D  HashAlg                       1    inz(x'00')
     D  Sequence                      1    inz(x'00')
     D  DataLngth                    10i 0 inz(15)
     D  Unused                        8    inz(*LOVAL)
     D  HashCtxPtr                     *   inz(%addr(HashWorkArea))

     D HashWorkArea    S             96    inz(*LOVAL)
     D Msg             S             50
     D ReceiverHex     S             16
     D ReceiverPtr     S               *   inz(%addr(ReceiverHex))
     D ReceiverChr     S             32
     D SourcePtr       S               *   inz(%addr(Msg))
     D StartMap        s            256
     D To819           s            256
     D CCSID1          s             10i 0 inz(37)
     D ST1             s             10i 0 inz(0)
     D L1              s             10i 0 inz(%size(StartMap))
     D CCSID2          s             10i 0 inz(819)
     D ST2             s             10i 0 inz(0)
     D GCCASN          s             10i 0 inz(0)
     D L2              s             10i 0 inz(%size(To819))
     D L3              s             10i 0
     D L4              s             10i 0
     D FB              s             12

     D                 ds
     D x                              5i 0
     D LowX                    2      2

      * Get all single byte ebcdic hex values
     C     0             do        255           x
     C                   eval      %subst(StartMap:x+1:1) = LowX
     C                   enddo

      * Get conversion table for 819 from 37
     C                   call      'QTQCVRT'
     C                   parm                    CCSID1
     C                   parm                    ST1
     C                   parm                    StartMap
     C                   parm                    L1
     C                   parm                    CCSID2
     C                   parm                    ST2
     C                   parm                    GCCASN
     C                   parm                    L2
     C                   parm                    To819
     C                   parm                    L3
     C                   parm                    L4
     C                   parm                    FB

      * Set message text
     C                   eval      Msg = 'message digest'
     C                   eval      DataLngth = %len(%trimr(Msg))

      * Now Change Msg to 819 from 37 using MI
     C                   callp     Convert( %addr(Msg)
     C                                     :%addr(To819)
     C                                     :%size(Msg))

      * Get MD5 for Msg
     C                   callp     Cipher( %addr(ReceiverPtr)
     C                                    :%addr(Controls)
     C                                    :%addr(SourcePtr))

      * Convert nibbles to characters
     C                   callp     cvthc( ReceiverChr
     C                                   :ReceiverHex
     C                                   :%size(ReceiverChr))

      * Display the "proof"
     C     ReceiverChr   dsply
     C                   eval      *INLR = '1'

     C                   return

Jon Paris
Partner400