Register article on using non-randomness of encrypted file content to reduce time needed to decrypt by brute force
ukcrypto at sourcetagged.ian.co.uk
Fri Aug 16 15:20:35 BST 2013
On 15 Aug 2013, at 16:00, Igor Mozolevsky wrote:
> On 15 August 2013 11:00, Brian Morrison <bdm at fenrir.org.uk> wrote:
>> Not seen this mentioned anywhere else yet:
>> Any opinions from those with direct knowledge of such techniques?
> Isn't the conventional wisdom to compress before encrypting to prevent
> thing like that?
"Conventional wisdom" - yes, actual wisdom, no. The compression layer
in SSL has been used to attack it (http://breachattack.com/).
The original article is nothing new - it's just a (partial) known
plaintext attack. Any predictability in the underlying plaintext of a
cyphertext gives you a handle to attack the cypher with. Most WW2
cryptanalysis was done around known or likely (partial) plaintexts.
The moral of the story is, never send anything predictable. If your
message is predictable mix something genuinely random into it.
> Igor M.
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