I have a question for my information security lab, which I am not able to find online. As the title says, is Diffie Hellman key exchange based on a one-way or a trapdoor function?

In case of RSA I would say it is based on a trapdoor function, since it is hard to factorize the modulo, if you don't know p and q.

Is Diffie Hellman also based on a trapdoor function, since it is hard to reverse the discrete logarithm, if you don't know the secret key?


No, the mathematical problem that is used for Diffie-Hellman is the Diffie-Hellman problem or DHP which is different from the trapdoor function that is behind RSA.

One way functions are for instance cryptographically secure hash functions.

  • $\begingroup$ Let me know if you need a mnemonic for that :P $\endgroup$
    – Maarten Bodewes
    Jan 21 '18 at 15:28
  • $\begingroup$ Oh okey, sounds good thanks :) Whats your mnemonic? :P $\endgroup$
    – 0x00
    Jan 21 '18 at 16:44

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