[messaging] Do quantum attacks/algos also lead to compromise of PFS?

[Watson Ladd]

On Sun, Jan 25, 2015 at 11:11 AM, Tao Effect <contact at taoeffect.com> wrote:
> As I understand it, quantum computers effectively halve the keyspace, so
> perhaps "suck" is too strong a term, but it isn't completely catastrophic
> for symmetric encryption the same way it is with RSA/ECC-like pubkey
> systems.
>
>
> That's not my understanding.
>
> The document I'm looking at [1] is quite damning and indicates QM systems
> break traditional symmetric ciphers like DES and AES in no time at all using
> "20 questions" algorithm:
>
> If we guess that each iteration will take 1 millisecond, then the total time
> for a known plaintext attack on DES is going to be 56 milliseconds.
>
> Cipher systems like AES-256 can also be broken is less than a second.

And the author is correct because what? Grover's algorithm would only
halve the key size. Shor's algorithm doesn't work. BCP is not known
equivalent to NP, and it's widely suspected not to be equal.

Sincerely,
Watson Ladd

>
>
> - Greg
>
> [1] Quantum Computers for Code Breaking, Dave D' Rave, 2600 Magazine
>
> --
> Please do not email me anything that you are not comfortable also sharing
> with the NSA.
>
> On Jan 25, 2015, at 11:06 AM, Tony Arcieri <bascule at gmail.com> wrote:
>
> On Sun, Jan 25, 2015 at 11:04 AM, Tao Effect <contact at taoeffect.com> wrote:
>>
>> "More good news: quantum computers suck at breaking symmetric encryption"
>>
>> Do you have a citation for that? It conflicts with what I've heard from
>> others.
>
>
> As I understand it, quantum computers effectively halve the keyspace, so
> perhaps "suck" is too strong a term, but it isn't completely catastrophic
> for symmetric encryption the same way it is with RSA/ECC-like pubkey
> systems.
>
> --
> Tony Arcieri
>
>
>
> _______________________________________________
> Messaging mailing list
> Messaging at moderncrypto.org
> https://moderncrypto.org/mailman/listinfo/messaging
>



-- 
"Those who would give up Essential Liberty to purchase a little
Temporary Safety deserve neither  Liberty nor Safety."
-- Benjamin Franklin