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You give each party a briefcase full of 4 TB hard drives full of random numbers generated from a USB attached atomic decay device. Now for 1,2,10 years dependi

You give each party a briefcase full of 4 TB hard drives full of random numbers generated from a USB attached atomic decay device. Now for 1,2,10 years depending on your rate of communication you can communicate using the one time pad. >why not just send the actual message via that mechanism? The point is you only have to exchange pads periodically, not every time you communicate.

a1a 13y ago
How do you encrypt the hard drives? I wouldn't trust some keys that had been lying around on an unencrypted hard drive for 1,2,10 years!
- omh 13y ago
  If I was using one-time-pads I'd probably be using them because I didn't trust encryption, so "unencrypted" wouldn't matter here. In real-world implementations I think the security is probably based around a large number of men with guns.
  - voidlogic 13y ago
    Exactly, men with guns secure the one time pad. The data sent using that pad is secure. Nit: I would consider one time pad to be a method of encryption.
    - omh 13y ago
      Nit: I would consider one time pad to be a method of encryption. Ah, true. But the encryption algorithm is much simpler to implement than most :-)
- admax88q 13y ago
  You don't get it at all.
andrewla 13y ago
I mean, what you're saying here is that in addition to one-time-pad based cryptography, there is a "give a briefcase to the person"-based cryptographic system. In reality, I think lot more briefcase-based transfers are "cracked", as it were, than SSL sessions. My problem is just that the proposed mechanism relies on already having an even more perfect mechanism, and thus cannot be the "only one", but is in fact strictly weaker than this other mechanism. So we have a contradiction, and we can get rid of the notion that there exists such a thing as an "unbreakable" system (or, alternatively, that it is a useful concept)
- admax88q 13y ago
  No, the notion of the unbreakable one time pad is a great notion to have around. It is the good standard for crypto systems. Yes it's unworkable in practice but that's exactly why nobody really uses it. It is useful for teaching and making comparisons.
  - voidlogic 13y ago
    Governments use it all the time. (Men with handcuffed briefcases and armed guards..) Before you send your submarine to sea for example, you can provide them with many gigabytes of one time pad. They can then use this for their most secret communication.
- voidlogic 13y ago
  No, this is a a breifcase full of one time pad. If you could fit 32 4 TB hard drives full of pad in the brief case that would allow you to send 128 TB in the future securely using something like an XOR one time pad. Assuming you are just sending ASCII and compress it before sending/XORing you could send a lot more then 128 TB of ASCII. This is pretty powerful. It means that organization which and periodically move physical assets securely can send information in a manner that is secure even if quantum computers reach their full potential.
  - _kst_ 13y ago
    Was "128 GB" a typo for "128 TB"? Incidentally, the mechanism for sharing the pad doesn't have to be 100% secure, as long as you can reliably detect any compromises. If someone opens the briefcase while it's in transit, you just generate new pads and send another briefcase. To compromise the system, an adversary has to compromise the pad in transit without being detected.

a1a 13y ago

How do you encrypt the hard drives? I wouldn't trust some keys that had been lying around on an unencrypted hard drive for 1,2,10 years!

omh 13y ago
If I was using one-time-pads I'd probably be using them because I didn't trust encryption, so "unencrypted" wouldn't matter here. In real-world implementations I think the security is probably based around a large number of men with guns.
- voidlogic 13y ago
  Exactly, men with guns secure the one time pad. The data sent using that pad is secure. Nit: I would consider one time pad to be a method of encryption.
  - omh 13y ago
    Nit: I would consider one time pad to be a method of encryption. Ah, true. But the encryption algorithm is much simpler to implement than most :-)
admax88q 13y ago
You don't get it at all.

andrewla 13y ago

I mean, what you're saying here is that in addition to one-time-pad based cryptography, there is a "give a briefcase to the person"-based cryptographic system. In reality, I think lot more briefcase-based transfers are "cracked", as it were, than SSL sessions. My problem is just that the proposed mechanism relies on already having an even more perfect mechanism, and thus cannot be the "only one", but is in fact strictly weaker than this other mechanism. So we have a contradiction, and we can get rid of the notion that there exists such a thing as an "unbreakable" system (or, alternatively, that it is a useful concept)

admax88q 13y ago
No, the notion of the unbreakable one time pad is a great notion to have around. It is the good standard for crypto systems. Yes it's unworkable in practice but that's exactly why nobody really uses it. It is useful for teaching and making comparisons.
- voidlogic 13y ago
  Governments use it all the time. (Men with handcuffed briefcases and armed guards..) Before you send your submarine to sea for example, you can provide them with many gigabytes of one time pad. They can then use this for their most secret communication.
voidlogic 13y ago
No, this is a a breifcase full of one time pad. If you could fit 32 4 TB hard drives full of pad in the brief case that would allow you to send 128 TB in the future securely using something like an XOR one time pad. Assuming you are just sending ASCII and compress it before sending/XORing you could send a lot more then 128 TB of ASCII. This is pretty powerful. It means that organization which and periodically move physical assets securely can send information in a manner that is secure even if quantum computers reach their full potential.
- _kst_ 13y ago
  Was "128 GB" a typo for "128 TB"? Incidentally, the mechanism for sharing the pad doesn't have to be 100% secure, as long as you can reliably detect any compromises. If someone opens the briefcase while it's in transit, you just generate new pads and send another briefcase. To compromise the system, an adversary has to compromise the pad in transit without being detected.