Re: MD5 and RPG or...?

[Scott Klement <midrange-l@xxxxxxxxxxxxxxxx>]

> Also, Perl/php, Linux, various *nixes and who knows what else have 
> md5sum and other commands or utilities.

FreeBSD's is called "md5" (no "sum" at the end).  Also, the OpenSSL 
command-line tool can calculate MD5 checksums with:

$ openssl md5 < myfile.csv
169fec5e6a5056dd0a2f5bd6adc1f252

> Under OS/400, we primarily have CIPHER or the _CIPHER builtin. But I'm 
> unclear about CIPHER (and probably MD5 to boot). It seems that the 
> maximum string length would be 16MB since a pointer is input to the 
> function. Some process for handling a document (streamfile) >16MB would 
> seem to require a chaining from segment to segment or something like 
> that.

Well, you don't have to do the whole thing in one string!  The _CIPHER 
builtin has the capability of specifying a "start" "middle" and "end" 
block so that you can keep feeding the data to it in chunks.

I've written MD5 utilities in RPG using _CIPHER that work just like the 
ones in Linux, BSD, etc. I've always thought it was wonderful to be able 
to download a file and compare the MD5 checksum on the server with what 
the client received.

But for some reason, whenever I talk to anyone else about this they think 
I'm crazy and prefer to compare the byte count instead of making a 
checksum. I'm glad to hear that there are others that can see the value!

> A google over AIX and MD5 left me with a sea of references that will 
> take a month to go through to see if PASE might help. QShell didn't have 
> anything that jumped out at me.

I'm told that OpenSSL can be made to run in PASE. (Though, I don't know if 
it requires V5R3 or if it works on earlier releases)  If so, that'll be 
able to do an MD5 checksum as described above.

> Is there any material on how to handle >16MB documents under OS/400?

Like I said, this isn't necessary. It's far more efficient to process the 
data in chunks rather than load the whole thing into memory at once.

(shrug) Maybe if you bug me enough, I'll write one and put it up on my web 
site. :)