On 7/10/19 4:47 AM, Antonin Houska wrote:
> Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
>> I don't think that works, because that'd mean we're encrypting the same
>> page with the same nonce over and over, which means reusing the reuse
>> (even if you hash/encrypt it). Or did I miss something?
>
> I found out that it's wrong to use the same key (or (key, IV) pair) to encrypt
> different plain texts [1], however this is about *stream cipher*. There should
> be some evidence that *block cipher* has similar weakness before we accept
> another restriction on the IV setup.
>
> [1] https://en.wikipedia.org/wiki/Stream_cipher_attacks#Reused_key_attack
There is plenty of guidance that specifies CBC requires unique,
unpredictable, but not necessarily secret IV. See for example Appendix C
here:
https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38a.pdf
Joe
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