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Re: AES encryption with J

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  To: comp.lang.java.security
On Thu, 29 Jan 2009 13:22:32 -0800 (PST), Ranger
<rangerdunadan@gmail.com> wrote, quoted or indirectly quoted someone
who said :

>I'm stumped.  I'm pretty sure that if you encrypt plaintext that is 16
>bytes long you should receive ciphertext that is 16 bytes long.
>However, I'm encrypting 16 byte plaintext and ending up with 32 byte
>ciphertext.  If I remove one character from the plaintext so it is 15
>bytes long I end up with a 16 byte ciphertext.

for sample code that works see http://mindprod.com/jgloss/aes.html

The essential problem is that encryption algorithm work on blocks,
usually of some power of 2. If you message is not that size, you need
to pad it, and when you decrypt it, discard the excess. That is
handled automatically when you select a padding algorithm.
-- 
Roedy Green Canadian Mind Products
http://mindprod.com

"Here is a point of no return after which warming becomes unstoppable
and we are probably going to sail right through it. 
It is the point at which anthropogenic (human-caused) warming triggers 
huge releases of carbon dioxide from warming oceans, or similar releases 
of both carbon dioxide and methane from melting permafrost, or both. 
Most climate scientists think that point lies not far beyond 2#C (4#F) C hotter."
~ Gwynne Dyer

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Re: AES encryption with J "Roedy Green" <roedy.green@THRWHITE.remove-dii-this> - 2011-04-27 16:08 +0000

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