[Cryptography] 3DES security?
Derek Atkins
derek at ihtfp.com
Wed Aug 26 20:36:31 EDT 2015
Henry,
On Wed, August 26, 2015 8:07 pm, Henry Baker wrote:
> What's the current best estimate for the (in)security of 3DES, in bits ?
2-key or 3-key 3DES? Generally 3DES implies 2-key EDE, which equates to
112-bit security. 3-Key 3DES uses more key bits, but my recollection is
that it doesn't significantly increase the security.. So I would treat
3DES as 112-bit security. To date, the best known attack against DES is
brute force.
The REAL issue with 3DES is that it's still only a 64-bit block size so
you have a 1 in 2^64 chance of randomly guessing the mapping from a
plaintext block to a cipher block, regardless of the keys. Of course you
need to repeat this mapping on every block, so it doesn't necessarily buy
you anything.
-derek
--
Derek Atkins 617-623-3745
derek at ihtfp.com www.ihtfp.com
Computer and Internet Security Consultant
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