Re: Regarding Decryption of AES128 encrypted data in RPGLE and query regarding CRC 32 [PRIVATE REPLY]

Hi Rishi,

I went to the website you mentioned,
https://www.devglan.com/online-tools/aes-encryption-decryption, and
tried decrypting


u3VtNgfyWU9faZc3Iaa8ZWbE5UZCfmC17yA4MyW0ghflt9dNQNDpCcgMZiG/kXPE4vv2CHL93B4iKiODHxxdVA==

with password (secret key)

6-9d15-ec98bcc81ec4275OIM1TS7LI

and I noticed a couple of things.

1. Since the encryption is AES128, the password length must be 16
bytes. The pswd in your program is 31 bytes.

2. The "encrypted" data is actually base64 encoded. In order to decrypt
it in RPG, you would first have to decode it from base64, then decrypt it.


On top of that, when I used the aforementioned website to encrypt
'whatever text', in AES with 128-bit key, mode ECB, and password
'mypasswordis16xy', the encrypted value is

x'831720A57F742CBB3A86AB24A3AA23AE'.

If I use the SQL encrypt_AES function, with the same password, the
encrypted value is

x'4CB947FF0025D5A6B96180506FFE4F23B96180506FFE4F23'.

The reason for this difference probably has something to do with the
following notes from IBM's SQL manual on the encrypt_AES function:

"The length attribute of the result depends on the arguments that are
specified:
* when /password-string/ is specified but a /hint-string/ is not
specified, the length
attribute of /data-string/ plus 24 plus the number of bytes to a
16-byte boundary.
* Otherwise, the length attribute of /data-string/ plus 64 plus the
number of bytes to
a 16-byte boundary."

Apparently IBM's encrypt_AES function includes more than just the
encrypted value in its result.

In short, it looks like you cannot use IBM's decrypt_AES function to
decrypt a value encrypted by anything other than IBM's encrypt_AES
function.

--
*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
petercdow@xxxxxxxxx <mailto:petercdow@xxxxxxxxx>
pdow@xxxxxxxxxxxxxx <mailto:pdow@xxxxxxxxxxxxxx>

/
On 9/30/2019 4:50 AM, Rishi Seth wrote:

I Know below is the IBM API for same but need a real working example

which

could decrypt data which is encoded using UTF8 or ACII. with 128 bit key
and Mode is ECB?

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