5 ms·

I know, like, nothing about this. But my wiki reading makes me think this is essentially a one time pad. you share the entangled bits, you send a message, the m

by jfoutz 8y ago

I know, like, nothing about this. But my wiki reading makes me think this is essentially a one time pad. you share the entangled bits, you send a message, the message tells you what to do if your entangled bit is one, or zero. nobody can mess with the entangled bits, or they lose entanglement, and the message becomes random. i dunno, it seems like if you had a bunch of them you could make a secure channel.

marcosdumay 8y ago
> i dunno, it seems like if you had a bunch of them you could make a secure channel. I don't think anybody solved man in the middle attacks against it yet. If the attacker takes hold of both the entangled channel and the classical channel, he can impersonate both parties and keep the conversation going. And you can't store those pairs. All those articles are about people that made them survive long enough for transmission. So you can't distribute them in person.
- AlexCoventry 8y ago
  That MITM attack is considerably more fragile than just reading a one-time pad during transit, though.
  - marcosdumay 8y ago
    Asymmetric encryption is cheaper, survives storage, requires only the transmission of public data, and is not fundamentally flawed like that. It is also more versatile.
    - akvadrako 8y ago
      But non-quantum encryption hasn't been mathematically proven to be secure. In the real world, you'll probably always use both and only if large quantum computers become available.
      - marcosdumay 8y ago
        Quantum computers are not needed for quantum encryption, and quantum computers do not break classical encryption in general, just the most used algorithms. They simply don't change the overall picture on this. Yes, non-quantum encryption has not been proven secure. That beats a known insecure systems at any time. You are also underestimating the cost of quantum crypto - it will only work on direct fiber, it can never be routed.
        akvadrako 8y ago
        Maybe some classical algorithm is immune to quantum computers, but none have been proven to be, unlike quantum encryption. Also, the Chinese have already demonstrated quantum channels over satellites - it doesn’t need fiber. The satellites are certainly acting as routers too.
        marcosdumay 8y ago
        Quantum encryption is broken today. Classical encryption may be broken, nobody knows. None of those is perfect, but one is better than the other.
Strilanc 8y ago
Quantum teleportation is in fact a quantum generalization of the classical one time pad. And it does form a secure channel, but with the same caveats as in the classical case (e.g. it's not authenticated). Many quantum things have classical analogues. For example, there is classical no cloning [1] and classical delayed erasure [2], though people will debate if these classical versions have really captured the "essence" of the quantum things. 1: https://marozols.wordpress.com/2012/05/21/three-myths-about-quantum-computing-part-2/ https://marozols.wordpress.com/2012/05/21/three-myths-about-... 2: http://algassert.com/post/1720 http://algassert.com/post/1720

by jfoutz 8y ago

marcosdumay 8y ago

> i dunno, it seems like if you had a bunch of them you could make a secure channel. I don't think anybody solved man in the middle attacks against it yet. If the attacker takes hold of both the entangled channel and the classical channel, he can impersonate both parties and keep the conversation going. And you can't store those pairs. All those articles are about people that made them survive long enough for transmission. So you can't distribute them in person.

AlexCoventry 8y ago
That MITM attack is considerably more fragile than just reading a one-time pad during transit, though.
- marcosdumay 8y ago
  Asymmetric encryption is cheaper, survives storage, requires only the transmission of public data, and is not fundamentally flawed like that. It is also more versatile.
  - akvadrako 8y ago
    But non-quantum encryption hasn't been mathematically proven to be secure. In the real world, you'll probably always use both and only if large quantum computers become available.
    - marcosdumay 8y ago
      Quantum computers are not needed for quantum encryption, and quantum computers do not break classical encryption in general, just the most used algorithms. They simply don't change the overall picture on this. Yes, non-quantum encryption has not been proven secure. That beats a known insecure systems at any time. You are also underestimating the cost of quantum crypto - it will only work on direct fiber, it can never be routed.
      - akvadrako 8y ago
        Maybe some classical algorithm is immune to quantum computers, but none have been proven to be, unlike quantum encryption. Also, the Chinese have already demonstrated quantum channels over satellites - it doesn’t need fiber. The satellites are certainly acting as routers too.
        marcosdumay 8y ago
        Quantum encryption is broken today. Classical encryption may be broken, nobody knows. None of those is perfect, but one is better than the other.

Strilanc 8y ago

Quantum teleportation is in fact a quantum generalization of the classical one time pad. And it does form a secure channel, but with the same caveats as in the classical case (e.g. it's not authenticated). Many quantum things have classical analogues. For example, there is classical no cloning [1] and classical delayed erasure [2], though people will debate if these classical versions have really captured the "essence" of the quantum things. 1: https://marozols.wordpress.com/2012/05/21/three-myths-about-quantum-computing-part-2/ https://marozols.wordpress.com/2012/05/21/three-myths-about-... 2: http://algassert.com/post/1720 http://algassert.com/post/1720