Re: Cipher MI instruction (MD5 function)

Have you checked the MI400 archives?  I want to think we've hit this once
or twice, but not lately....

Have you looked at Leif's MI ebook?

Don in DC


> Hi there,
>
> I am trying to to use the MD5 function to store/check passwords, but
> things
> aren't working as expected. Or, to put it better, they work as expected
> but
> only once.
>
> The second time the cipher function is invoked in the same program
> execution, it will generate a MCH5601 exception, and be done with it.
> First
> time works perfectly, but the second will always fail.
>
> I declare the procedures I am using:
>
> Dcvthc PR EXTPROC('cvthc')
> D 1
> D 1
> D 10i 0 VALUE
>
> DCipher PR EXTPROC('_CIPHER')
> D * VALUE
> D * VALUE
> D * VALUE
> I declare the control ds and work variables (as seen in
> http://archive.midrange.com/midrange-l/200006/msg01334.html)
>
> DControls     DS
> D Function      5i  0 inz(5)
> D HashAlg       1     inz(x'00')
> D Sequence      1     inz(x'00')
> D DataLngth     10i 0
> D Unused        8     inz(*LOVAL)
> D HashCtxPtr    *     inz(%addr(HashWorkArea))
> DHashWorkArea S 96    inz(*LOVAL)
> DDestinoHex   S 16
> DDestinoChr   S 32
> DDestinoPtr   S *     inz(%addr(DestinoHex))
> DFuentePtr    S *     inz(%addr(Fuente))
> DFuente       S 8
> I check against user provided password (CONTRA) against the one stored (
> USER.CONTRA, already stored in DB)
>
> dow CONTRA <> USER.CONTRA;
>   exFmt AskForPass;
>   fuente    = CONTRA;
>   DataLngth = %len(%trimr(fuente));
>   Cipher(%addr(DestinoPtr) : %addr(Controls) : %addr(FuentePtr));
>   CVTHC(DestinoChr : DestinoHex :%size(DestinoChr));
> endDo;
>
> If the user puts his/her password correctly in the first attempt, things
> go
> on and everything is nice. Otherwise, he gets another chance, and then the
> program will fail (right or wrong password, it doesn't matter) giving
> error
> message MCH5601, reason code X'0000'.
>
> I tried to find clues at
> http://publib.boulder.ibm.com/iseries/v5r1/ic2924/tstudio/tech_ref/mi/CIPHER.htm
> but
> it didn't help.
>
> Anyone has a deeper insight on this?
>
> Regards,
>
> I.-
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