Android Question Checking AES encryption server side

Discussion in 'Android Questions' started by ALBRECHT, Aug 5, 2019.

  1. ALBRECHT

    ALBRECHT Active Member Licensed User

    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
     
    Last edited: Aug 5, 2019
  2. techknight

    techknight Well-Known Member Licensed User

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

    ALBRECHT Active Member Licensed User

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

    techknight Well-Known Member Licensed User

    ?

    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.
     
    Last edited: Aug 5, 2019
  5. ALBRECHT

    ALBRECHT Active Member Licensed User

    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
     
  6. Jeffrey Cameron

    Jeffrey Cameron Active Member Licensed User

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