Re: Does Block Size Affect Security

From: Paul Crowley (paul@JUNKCATCHER.ciphergoth.org)
Date: 03/30/03

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    From: Paul Crowley <paul@JUNKCATCHER.ciphergoth.org>
Date: Sun, 30 Mar 2003 09:30:00 GMT

    "Xizor" <nope@nope.com> writes:
    > I'm new to encryption and right now I'm using a C++ wrapper for
    > Rijndael. My question is this: does the block size affect the
    > security? Is there an optimal relationship between the size of the
    > block and the size of the key? Thanks in advance.

    Only the 128-bit block size has seen thorough analysis and been
    standardised as AES.

    If you can, use something like SSL or GPG for crypto rather than
    trying to roll your own system by hand; there are many more pitfalls
    than you might guess and you'll almost certainly end up with something
    insecure. If you must do it yourself, though, remember to use a
    proper chaining mode and MAC. CCM mode is probably the easiest to get
    right. 

    -- 
  __  Paul Crowley
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