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From "Leo Li" <liyilei1...@gmail.com>
Subject Re: [classlib][security]How to discard padding data after decryption.
Date Thu, 15 Nov 2007 03:28:07 GMT
On 11/14/07, Yuri Dolgov <dolgov.g.yuri@gmail.com> wrote:
>
> Hello Leo,
>
> For "no padding" modes there is no padding added to the data encrypted.
> Though
> you have to encrypt only data aligned to cipher block size.



   Thank you, Yuri.
   Now I know if "no padding" mode is adopted, how to manage the padding is
the job of the caller.

Thanks,
> Yuri
>
> On 11/14/07, Leo Li <liyilei1979@gmail.com> wrote:
> >
> > Here is an exmple:
> >
> >     byte[] data = ...; // data encrypted with DES-CBC-CRC
> >     byte[] keyBytes = ...;  // the DES key used to encrypt data.
> >     final byte[] iv = new byte[]
> >         { ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00, (
> > byte
> > ) 0x00, ( byte ) 0x00, ( byte ) 0x00,
> >             ( byte ) 0x00 };
> >     Cipher cipher = Cipher.getInstance( "DES/CBC/NoPadding" );
> >     SecretKey key = new SecretKeySpec( keyBytes, "DES" );
> >     AlgorithmParameterSpec paramSpec = new IvParameterSpec( iv );
> >     cipher.init( Cipher.DECRYPT_MODE, key, paramSpec );
> >     byte[] decryptedData = cipher.doFinal( data );
> >
> >     Has the decryptedData got here already discarded the padding bytes?
> If
> > not, how to discard these data?
> >
> >    Is there somebody familar with this?
> >    Thanks in advance.
> >
> > --
> > Leo Li
> > China Software Development Lab, IBM
> >
>



-- 
Leo Li
China Software Development Lab, IBM

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