Re: FieldProc Error - column has returned invalid data on a Zoned Numeric column -- RPG400-L

nathan - this forum has the brightest talent in the industry. And I'm
always amazed at how willing they are to help.

I'm curious how you arrived at 8x as long? What test did you do?

How your field procedure program is designed and developed is obviously the
utmost underlying factor on what causes the performance hit.

jay

On Mon, Mar 30, 2020 at 9:16 AM Nathan Hughes <nathan.hughes@xxxxxxxxxxxxx>
wrote:

First, I want to thank everyone who has contributed to this, you all have
been immensely helpful with this issue! I've been able to make some
headway in this, and what I'm noticing is a drastic increase in time it
takes to read records. I knew that there would be a performance hit, but 8
times as long!? Has anyone else noticed this?

I know this is off topic, but does anyone know if enabled TDE (transparent
data encryption) on the ASP level is any better? Or worse?

Thanks,
Nathan Hughes
Software Developer

601.499.2131 Office
280 Trace Colony Park
Ridgeland, MS 39157

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Jay
Vaughn
Sent: Sunday, March 29, 2020 8:37 PM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: FieldProc Error - column has returned invalid data on a Zoned
Numeric column

Vern,

No sql at all actually.
Though way underneath the covers the method does use the sql engine, I
believe.

The solutions comes by the way of Mark Waterbury. I myself, was in the
middle of developing an OA handler as well when he graciously shared his
alternative. It was truly a gift at the time as my entire projects success
was hinging on the ability to overcome this “predicament”.

Any pgm preceeding the usage of the encrypted file/field can be issued an
ovrdbf/opnqryf combination and way under the covers the sql engine is
invoked and processes the setll/read as it should by using the clear txt
value and not the encoded value. An incredibly simple yet effective
method. Thanks again Mark.

Anyhow this functionality is demonstrated in my download.

Jay

On Mar 29, 2020, at 8:01 PM, Vernon Hamberg <vhamberg@xxxxxxxxxxxxxxx>

wrote:

Hi Jay

I suspect my mention last week of the handler I wrote has muddied the

waters. I did not at first understand that Mike was talking about creating
the FIELDPROC. I don't remember the exact timing, but I think we got
through that early in this thread.

So my question, related to your post about an end to end FIELDPROC

solution (very cool and generous, BTW) - do you require that people use
embedded SQL for this, or SQL procedures? To avoid the problem with a
FIELDPROC over key fields? The vendor for who i wrote the handler was faced
with customers who could not afford to change everything to embedded SQL.

Regards and stay well!
Vern

On 3/29/2020 6:06 PM, Jay Vaughn wrote:
The only thing Vern's OA handler is going to address is the side
effect that comes along with encrypted key fields paired with native
I/O combination of setll/read. Not to sell the handler short. It
was a huge accomplishment to have an handler developed to translate
any native i/o operation to the sql equivalent., so not trying to
sell it short... but as it relates to encryption and field
procedures, this is the area in which it is needed.

And this is applied to the application layer far after the field
procedure is created and attached to the file//field

jay

Jay

On Tue, Mar 24, 2020 at 8:45 AM Mike Jones
<mike.jones.sysdev@xxxxxxxxx>
wrote:

Hi Vernon,

It means field procedure programs can't run SQL statements. It also
means field procedure programs can't call other commands or programs
that run SQL statements. This even applies to calling IBM commands

and programs.

IBM's V7R3 SQL Reference manual page 1175, for the CREATE TABLE
statements for the FIELDPROC attribute says "Designates an
external-program-name as the field procedure exit routine for the
column. It must be an ILE program that does not contain SQL. It cannot

be a service program."

I tried to make a field procedure program that would largely
self-deploy, where it would create a key store file (via IBM's API),
and generate / populate it with an encryption key, but calling the
API to create a key store file would not run. When I looked into
why, it was because IBM's API to create a key store file runs SQL,
and I found documentation that you can't do that.

I don't know why it is like that, just that it is.

Perhaps using an Open Access handler is a workaround, I don't know.

Those were my findings at the V7R3 level. I've not tried it on V7R4.

Mike

On Mon, Mar 23, 2020 at 9:39 PM Vernon Hamberg
<vhamberg@xxxxxxxxxxxxxxx>
wrote:

Mike - I'm not sure exactly what your statement means. If you mean
that the programs themselves can't have embedded SQL, that's
something I don't know.

Now what I do know is that if a key field has a FIELDPROC added to
it, that the resulting order in RPG is probably incorrect. I wrote
an Open Access handler to turn all DISK IO in RPG into SQL
statements - only change in the RPG is to add the handler to the
F-spec. I wrote this for Townsend Security (this was publicly
announced, so no secrets being revealed here), I believe there is a
relationship now with Syncsort, if anyone has a need for this - I'm
not working for either company, so this is not a <verndor option>!!

Vern

On 3/23/2020 11:00 PM, Mike Jones wrote:

Nathan

Field proc programs don't yet allow the use of any SQL. They also

don't

yet support calling a program or command that directly or
indirectly

runs

SQL statements. Example: you can't call IBM's API to create a key

store

file, from inside a field procedure program, because that API runs
SQL

in

its plumbing.

I've gotten all that encryption field procedure stuff to work
well,

but i

was a PITA getting it all to work. I utilized code from at least
a

handful

of sample programs.

- AES 256-bit encryption
- DEKs (data encryption keys) stored in key store files.
- Using KEKs (key encrypting keys) to encrypt the DEKs (data

encryption

keys), also stored in key store files.
- Using master keys to encrypt the key store files.
- Using tokens with the encryption APIs so the keys can't be

retrieved

even under debug.

If you're trying to take a zoned decimal number, encrypt it, and
store

it

in the database, you need to store the result in:

- A CHAR or VARCHAR column with the FOR BIT DATA attribute

applied,

which uses CCSID 65535.
- A BINARY column
- A VARBINARY column
- A BLOB column
- Or the DDS file defined equivalent of one of the above.

The encrypted data is a binary string that requires one of those
data

types

to store the results. Encrypted data doesn't conform to the set of

hex

values that are allowable for storage in a zoned or packed decimal

column,

Get the IBM Redbook "IBM System i Security: Protecting i5/OS Data
with Encryption". In the July 2008 version of that book, see
chapter 7 "Database Considerations", section 7.2, pages 78 and 79
in particular,

talk

about storage requirements of the encrypted data.

Another great PDF book is "Protecting IBM i data with encryption"
by

Kent

Milligan and Beth Hagemeister (March 2014). Read pages 31 through
33

for

storage requirements.

When you apply the field procedure to a column (ALTER TABLE ALTER

COLUMN),

it calls the field procedure to encrypt that column for ALL rows
of the table.
When you drop a field procedure from a column (ALTER TABLE ALTER

COLUMN),

it calls the field procedure to decrypt that column for ALL rows
of the table.

I imagine a field procedure could be used for a non-encryption
purpose, although I've not tried that (no use case comes to mind at

the moment).

Assuming that is allowed, a field procedure that returns zoned
decimal

data

for storage in a zoned decimal column is fine to do, but not with

encrypted

data.

HTH,

Mike

On Mon, Mar 23, 2020 at 4:48 PM Vernon Hamberg <

vhamberg@xxxxxxxxxxxxxxx

wrote:

Nathan

Is the numeric column in question a key of the file? Are you
using native record-level access? If either, then RPG might give
you

problems.

I thought it was only with keyed columns, but maybe not.

You might try using SQL to process the file.

Vern

On 3/23/2020 3:26 PM, Nathan Hughes wrote:

First I want to apologize for my ignorance in RPGLE...we
typically

don't

use this programming language, but have to for FieldProc purposes.

I've

researched this issue for a couple weeks now, and cannot find a

resolution.

I'm currently trying to write a field procedure program. I have
taken

the

IBM RPGLE example (

https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fw
ww.ibm.com%2Fsupport%2Fknowledg...yfpexample.htm&data=01%7C01%7
Cnathan.hughes%40badgepass.com%7Cb53cc8c797b842c7e97508d7d44ad949%7
C224758f072634e52a6e4f5db2afdf99e%7C0&sdata=F6fRwGRLwT2%2F7nG3o
KYMocGBkMsP38fWksBeCDfuBj4%3D&reserved=0<

https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fww
w.ibm.com%2Fsupport%2Fknowledgecenter%2Fssw_ibm_i_73%2Fsqlp%2Frbafyf
pexample.htm&data=01%7C01%7Cnathan.hughes%40badgepass.com%7Cb53c
c8c797b842c7e97508d7d44ad949%7C224758f072634e52a6e4f5db2afdf99e%7C0&
amp;sdata=5ZomdBu5GujxBVXT4u2PG10YG0z3hTUlReUgtUowCf0%3D&reserve
d=0

),

and started to modify it to work for us.

Here is the table that was created for testing purposes:
********** Beginning of data *************************************
A R REC
A ECNUM 16S 0 COLHDG('NUMBER')
A ALIAS(EC_NUMBER)
A ECALPHA 32A COLHDG('ALPHA')
A ALIAS(EC_ALPHA)
************* End of data
****************************************
The program from the link above allows for several SQL types,
clob,

varchar, char, blob, etc., but I needed to add zoned numeric. To

begin,

I

studied and stepped through the program to see what it was doing,
and thought I had a good understanding of how it worked. I then
started

adding

what appeared as necessary for the SQL_TYP_ZONED (488).

When I send the 'ALTER TABLE' command and set the FieldProc
program

on

a

column, the first call is to Register(function code: 8), the next
is Encode(function code: 0) to encode the values in said column.

I set a breakpoint at the end of the program, and evaluated the

parameters when setting the FieldProc on a VARCHAR and ZONED
NUMERIC columns, and besides being different data types all
appears correct,

but

the ZONED NUMERIC column abruptly stops with the error below
after the register call.

Message ID . . . . . . : SQL0685 Date sent . . . . . . :
03/18/20 Time sent . . . . . . : 16:17:04

Message . . . . : Field procedure on column ECNUM has returned

invalid

data.

Cause . . . . . : Field procedure on column ECNUM has returned

invalid

data.

Recovery . . . : Change the field procedure to return valid data.

Thank you in advance for any help you can give on this.

Thanks,
Nathan Hughes
Software Developer

[BadgePass]
601.499.2131 Office
280 Trace Colony Park
Ridgeland, MS 39157

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