On 7/10/19 4:47 AM, Antonin Houska wrote: > Tomas Vondra <tomas.von...@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 -- Crunchy Data - http://crunchydata.com PostgreSQL Support for Secure Enterprises Consulting, Training, & Open Source Development
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