6 ms·

One time pads are perfect! Everything less than that trades security for convenience. So true.

• omginternets 9y ago
  Key management is a very real issue in cryptographic systems. Arguably, convenient key management improves security. Simplistic interpretations are the bane of security engineering, especially where human factors are involved.
  • rietta 9y ago
    Indeed. I'm about to have a form of that conversation with a client today. Just encrypting columns in your database is of some value, but having the symmetric key in an environment variable (a common practice) is not going to prevent a breach when the data and the key are compromised at the same time.
• strictnein 9y ago
  If used properly they are, but many times people get lazy and reuse pads or use pads that are too short.
• _jal 9y ago
  Of course, that perfection is achieved by shifting all your risk to key distribution. I think of OTPs as a form of time-shifting. Think of it this way: if you and your correspondent have viable OTPs, that implies that, at some point in the past, you securely communicated that OTP. Since it is (at least) the length of a future message, you could have just passed a secure message then. Instead, you passed something that enables passing a secure message now.
  • libeclipse 9y ago
    Imagine implementing your amazing solution in real life. I don't see a situation being frequent where you'd know the message weeks or months in advance of when you send it. If we follow your scheme, there's no encryption; we just meet up when we need to communicate. What if we're on opposite sides of the earth? If we had exchanged keys months earlier, this wouldn't be a problem.
    • _jal 9y ago
      I must have explained poorly. I was not proposing "just communicate securely in advance". I was highlighting the problem with OTPs. The fact that your key material is the same size as the message means all your security is in the key, thus in your key distribution method. Among other problems, this means no rekeying without replicating your original hand-off - you can communicate exactly as many bits as your previously securely exchanged, no more.
      • libeclipse 9y ago
        > means all of your security is in the key ...erm, isn't that the point?
        • _jal 9y ago
          Speaking of points, I can't tell if you're intentionally missing mine, but either way this is unproductive. If you're sincerely confused, please read up a bit. The Wikipedia page isn't a terrible place to start.
          • libeclipse 9y ago
            No I mean I understand where OTP falls short, but you're either really bad at conveying your viewpoint, or you're simply plain wrong. Yes, with OTP you need to exchange keys and this shifts all of the security to key exchange, and while this wouldn't be a problem in other ciphers, it's a problem in OTP because of its other properties and shortfalls. So at most I feel as though it's a security/convenience tradeoff; a tradeoff that's substantial or even dangerous in certain situations.
      • Nomentatus 9y ago
        USBs carry a lot - and couriers are terrorists usual way of doing business. I don't see this as any barrier.