• Justin@lemmy.jlh.name
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    1 month ago

    Quantum computers are not advanced enough to break RSA/EC yet. NSA might have some secret backdoors, but the recent focus on quantum-resistent encryption from both the public and private sectors (see TLS and Mullvad) has nothing to do with China.

    What is a one-time crypto, and how does it allow you to avoid the use of quantum-vulnerable asymmetric encryption such as the algorithms used for HTTPS?

    • AbelianGrape@beehaw.org
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      1 month ago

      I’ve only ever seen “one-time” in cryptography to refer to One-Time Pads (OTP). They are literally uncrackable (because every possible plaintext could be encoded by every possible ciphertext) but they achieve that by using a shared private key. The cipher becomes attackable if the key is re-used, hence the “one-time.”

      But that key has to be exchanged somehow, and that exchange can be attacked instead. Key exchange algorithms can’t necessarily transfer every possible OTP which means eavesdropping on the exchange would make an OTP attackable. So the best option we know of that doesn’t require secret meetings to share OTPs* really is to use RSA encryption. Once we have efficient quantum-resistant schemes, they’ll be the best option we know.

      * and let’s be honest, secret meetings can be eavesdropped on as well.

    • booly@sh.itjust.works
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      1 month ago

      One time pads are perfect encryption, but the problem is that the key length needs to be longer than the message length. So if you have the ability to get the symmetric key to the recipient securely, then you had the ability to get the whole message to the recipient securely.