The most efficient public key encryption method

Question

There seems to be a lot of hype about asymmetric public key encryption. RSA, PGP ... etc. You have a set of two keys and distribute them so that you can only encrypt the message, or only you can decrypt the message. One method provides a way to verify the sender, and the other provides a way to protect the message. (Feel free to correct me if I am wrong.)

Now, I have also read about the Diff-Hellman class for Key-Exchanges. This seems more secure since you can check the sender and protect the message with the keys, as each “conversation” requires a computed “shared key”.

So, to my question: are there any serious flaws (besides the configuration requirements) for using Diffie-Hellman in a more standard form of public key encryption?

Or to be honest. If Diffie-Hellman makes more sense, why is this not a standard form of encryption?

Answer 1

Symmetric and asymmetric ciphers are two completely different things. You cannot directly compare them.

Symmetric ciphers are used to encrypt messages with a shared secret. These are algorithms such as DES, AES, blowfish, etc.

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Answer 7

The main problem with RSA is that it is slow. In fact, what early versions of PGP (I'm not sure what modern versions do, maybe they haven't changed) used Diffie-Hellman key exchange to distribute the key to some quick symmetric cipher, and then just use it for the body of the message.