Android Question Checking AES encryption server side

[ALBRECHT]

Hello,

I need to check , server side an AES encryption for my own api create with asp.

the string in encrypted with B4XCipher and has been sent with poststring, the recept is ok

but server side, i have trying to use rijndael library functions but I can not decipher correctly

found there : http://www.freevbcode.com/ShowCode.asp?ID=2389


Could you have an idea or another method (in asp, php or other) to put me on the way for that ?

thanks
Michel

 

[techknight]

Check for endianness issues. Try byteswapping the key, or message, or both.

 

[ALBRECHT]

please, do you have eventualy a link to let me analyse that decyphering methode ?

 

[techknight]

?

You posted a link to VB code. its all there.... Not sure what your asking.

The difference I see, is the VB code is Rijndael, which isnt "exactly" AES.

See here:
https://stackoverflow.com/questions/748622/differences-between-rijndael-and-aes

The VB is using 32 bytes which is 256 bit. AES is 128 bit.

If your using the VB code as 128 bit, and it still doesnt work, then check for the endianness. I dont have the source code of B4XCipher, so I dont know if its little endian or big endian.

But the Endianness between the two systems have to be the same.

 

[ALBRECHT]

ok i understand, im going to go further in that way with the correct endianness
and if i m able to understand how works B4XCipher ...
Thanks

 

[Jeffrey Cameron]

See this post, it may be helpful: https://www.b4x.com/android/forum/t...-vs-vb-net-2017-encryption.83598/#post-529673