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Would PGP work as a method of sharing the AES key, as shown below, and what would be the flaws with this method of encryption?

  1. Server sends PGP public key
  2. Client generates (uses as AES key for networking) and encrypts random 128 byte key with PGP public key
  3. Server decrypts data with PGP private key and uses as AES key for networking

Obviously current standards such as SSL/TLS would work better, and the keys would need to be checked at some sort of CA (perhaps a public PGP key server)

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1 Answer 1

That method is not protected against man-in-the-middle attacks unless the public key can be trusted (using the normal PGP trust model). Otherwise yes, it should be a good method of sharing an AES key.

It would be identical to the method that SSL uses to share keys using RSA (unless the safer method that deploys Ephemeral Diffie-Hellman with RSA authentication is applied). Note that your scheme does therefore not provide perfect forward secrecy.

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Of course, you can then also mess up the networking part, by forgetting the authentication tag or padding oracle attacks. –  owlstead May 10 at 14:52
    
Assuming I understand perfect forward secrecy, could I not just sign a randomly generated public key with the server's real public key, so that way we know who it is. –  Hector Mongoose May 10 at 15:04
    
Given the rest of your comment, I'm not sure that the first assumption is correct... Then again, I may have misunderstood. –  owlstead May 10 at 15:07

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