Re: Reg: DES Decryption in IBMi

[Suren K <suren7437@xxxxxxxxx>]

Hi All,

Any ideas from someone?

How to use the IV as an array of data and how to use PKCS5Padding?

When I use QC3PO as '1' (Remove padding) I am getting the error during
decryption as CPF9DC3 - Unable to decrypt data or key

Any ideas will be very much appreciated.

Regards,
Suren

On Tue, Jul 26, 2022 at 10:21 AM Suren K <suren7437@xxxxxxxxx> wrote:

> Hi Everyone,
>
> Currently I have a scenario like Java will encrypt an image using
> DES/CBC/PKCS5Padding with an 8 character length Key and IV they were using
> in an array of data like IVBytesJpg = new byte[]{44, 140, (byte)146, 35,
> 26,(byte) 149, (byte)136, 150 } and store the encrypted image into an
> Windows Share Drive (/WindosIP/Shared Drive/Image File).
>
> I am accessing the Windows share drive from iSeries and decrypting the
> image and exposing the image in base64 format in REST API.
>
> To achieve this I am using the below steps
>
> Step 1: Fetch the encrypted image from Windows Share drive using the below
> code in rpgle (using QNTC)
>
> dcl-s Wrk_WindowsImage    sqltype(clob_file);
> dcl-s Wrk_Image                  sqltype(clob:500000);
>
> Wrk_WindowsImage_FO = SQFRD;
> Wrk_WindowsImage_Name = /QNTC/WindosIP/Shared Drive/Image File
> Wrk_WindowsImage_NL = %len(%trimr(Wrk_WindowsImage_Name));
> exec sql values :Wrk_WindowsImage into :Wrk_Image;
>
> This way I can fetch the encrypted image from Windows Share drive into an
> CLOB variable
>
> Step 2: Decrypt the Image
>
> Using the IBMi API Qc3DecryptData and Algorithm Format as ALGD0200 and Key
> Format as KEYD0200
>
> In the algorithm ALGD0200, I am not sure how to use PKCS5Padding, So I am
> just using the Pad option QC3PO as '0' (Do not remove padding).
>
> I am not sure how can I use the array of data (IVBytesJpg = new byte[]{44,
> 140, (byte)146, 35, 26,(byte) 149, (byte)136, 150 }) as input for IV, if
> someone shed some light it would be great.
>
> Step 3: Convert the image into Base64 format
> Convert the decrypted value in Base64 format. For this I am planning to
> use Scott Klements Base64 utility (https://www.scottklement.com/base64/)
>
> Could you please help me out in how to use the PKCS5Padding and array of
> data as IV in Qc3DecryptData API?
>
> Regards,
> Suren