5 ms·

Isn't the problem with one time pads distributing the pad? Like, you would have to walk to a bank and have them hand you a piece of paper... and tellers could r

by gleenn 4y ago

Isn't the problem with one time pads distributing the pad? Like, you would have to walk to a bank and have them hand you a piece of paper... and tellers could read the paper before handing it to you. So basically so ineffective in practice as to be unusable?

nelgaard 4y ago
The distribution part have gotten a lot easier. I would be very possible for banks to give all their customers USB devices with a few GByte of one time pads and keep a copy of those same GBytes in their own systems. And most banks still have brick-and-mortar stores where customers could come and identify themselves and collect their one time pad. And a GByte of keypads would cover your banking need for a long time. The problem is more that it works for some one-to-many relationsships such as banks, but not many-to-many relationships, such as emails, websites, etc. There have to be second or third parties. On the hand, a lot of people seems to log in everywhere with Google Sign In or similar anyway. And we could instead all have Google or Amazon devices with GBytes of one time pads. And that could be used to set up symmetric encryption, which should be more resistant to quantum computer attacks. The only drawback is that we would have to trust the third party and everyone who could compromise the third party and every government that could put pressure on the third party :-)
armb 4y ago
Quantum Key Distribution. You can prove that the key hasn't been intercepted. But since that means you need a direct point to point connection with no routers, switches, hubs, amplifiers/repeaters etc., it only works for a tiny fraction of cases. https://en.wikipedia.org/wiki/Quantum_key_distribution https://en.wikipedia.org/wiki/Quantum_key_distribution
b112 4y ago
I remeber in the very early 2000s, a guy had a stopwatch sized whos-it, and it kept flashing numbers on it. Updated every 5 minutes. Apparently, some cesium based list of numbers, again, was 20 years ago. Point is, it was a one time pad...
- dekhn 4y ago
  You mean this? https://en.wikipedia.org/wiki/RSA_SecurID https://en.wikipedia.org/wiki/RSA_SecurID I'm not sure but I don't think this is OTP?
  - g_p 4y ago
    Indeed, they're not one-time pads - they are symmetric authenticators where both sides hold the same seed, and iterate a PRNG or similarly iterable function every N units of time (say, 30 seconds), to give you the same new output, based on the same starting seed. Think stream cipher output, with an initialisation vector. They are often called OTPs though (i.e. one-time passcodes), just to cause confusion.
- djmips 4y ago
  A Whatsit. A Thingamabob. A doohickey. I remember those - people still use them I think?
fragmede 4y ago
so print it via pressure into the inside of a sealed envelope? that's how they send me my PIN.
- itcrowd 4y ago
  (not sure if replying to troll..) The argument against OTP is that by securely distributing the key of the same length as your message, you ostensibly already have a secure messaging mechanism; why would you need the OTP?
  - gambiting 4y ago
    Well no, that's not true - a bank could issue you with a one-time-pad long enough to encrypt the next 10000 messages with you, and use that over the years - they just need to tell you which line of the key is needed to decrypt your message. In that scenario you only need to guarantee security for the first time the key is distributed(for example a file sent to you when the account is opened).
    - gleenn 4y ago
      So now people have to keep a piece of paper around or somehow put it into some software and not lose access. You're right, it would work. In reality, people can't even be bothered to use a password manager or understand even the most simple of new security software, let alone even remember their password. That makes it completely intractable as a solution.
      - gambiting 4y ago
        I mean, the scenario being discussed here is some kind of "world ending" situation where all known encryption is broken. So you either do it the way I described it, or you don't have any encryption whatsoever. I think under those conditions people would adjust. It isn't an alternative to our current arrangements. Also: my bank access is done entirely through an app that obscures its internal implementation. It could already be using OTP and it wouldn't make any difference to me, nor would I be able to tell(my point is that the user wouldn't need to keep a piece of paper that they would need to type in anywhere - the internal implementation of tools we use every day would change, but most users wouldn't even notice)

by gleenn 4y ago

nelgaard 4y ago

The distribution part have gotten a lot easier. I would be very possible for banks to give all their customers USB devices with a few GByte of one time pads and keep a copy of those same GBytes in their own systems. And most banks still have brick-and-mortar stores where customers could come and identify themselves and collect their one time pad. And a GByte of keypads would cover your banking need for a long time. The problem is more that it works for some one-to-many relationsships such as banks, but not many-to-many relationships, such as emails, websites, etc. There have to be second or third parties. On the hand, a lot of people seems to log in everywhere with Google Sign In or similar anyway. And we could instead all have Google or Amazon devices with GBytes of one time pads. And that could be used to set up symmetric encryption, which should be more resistant to quantum computer attacks. The only drawback is that we would have to trust the third party and everyone who could compromise the third party and every government that could put pressure on the third party :-)

armb 4y ago

Quantum Key Distribution. You can prove that the key hasn't been intercepted. But since that means you need a direct point to point connection with no routers, switches, hubs, amplifiers/repeaters etc., it only works for a tiny fraction of cases. https://en.wikipedia.org/wiki/Quantum_key_distribution https://en.wikipedia.org/wiki/Quantum_key_distribution

b112 4y ago

I remeber in the very early 2000s, a guy had a stopwatch sized whos-it, and it kept flashing numbers on it. Updated every 5 minutes. Apparently, some cesium based list of numbers, again, was 20 years ago. Point is, it was a one time pad...

dekhn 4y ago
You mean this? https://en.wikipedia.org/wiki/RSA_SecurID https://en.wikipedia.org/wiki/RSA_SecurID I'm not sure but I don't think this is OTP?
- g_p 4y ago
  Indeed, they're not one-time pads - they are symmetric authenticators where both sides hold the same seed, and iterate a PRNG or similarly iterable function every N units of time (say, 30 seconds), to give you the same new output, based on the same starting seed. Think stream cipher output, with an initialisation vector. They are often called OTPs though (i.e. one-time passcodes), just to cause confusion.
djmips 4y ago
A Whatsit. A Thingamabob. A doohickey. I remember those - people still use them I think?

fragmede 4y ago

so print it via pressure into the inside of a sealed envelope? that's how they send me my PIN.

itcrowd 4y ago
(not sure if replying to troll..) The argument against OTP is that by securely distributing the key of the same length as your message, you ostensibly already have a secure messaging mechanism; why would you need the OTP?
- gambiting 4y ago
  Well no, that's not true - a bank could issue you with a one-time-pad long enough to encrypt the next 10000 messages with you, and use that over the years - they just need to tell you which line of the key is needed to decrypt your message. In that scenario you only need to guarantee security for the first time the key is distributed(for example a file sent to you when the account is opened).
  - gleenn 4y ago
    So now people have to keep a piece of paper around or somehow put it into some software and not lose access. You're right, it would work. In reality, people can't even be bothered to use a password manager or understand even the most simple of new security software, let alone even remember their password. That makes it completely intractable as a solution.
    - gambiting 4y ago
      I mean, the scenario being discussed here is some kind of "world ending" situation where all known encryption is broken. So you either do it the way I described it, or you don't have any encryption whatsoever. I think under those conditions people would adjust. It isn't an alternative to our current arrangements. Also: my bank access is done entirely through an app that obscures its internal implementation. It could already be using OTP and it wouldn't make any difference to me, nor would I be able to tell(my point is that the user wouldn't need to keep a piece of paper that they would need to type in anywhere - the internal implementation of tools we use every day would change, but most users wouldn't even notice)