how to exchange a secret key across the internet?

Question

plz any one help me

Answer 1

The best way to exchange confidential information over insecure communication lines like the Internet is by using public-key cryptography. It uses two keys - a public one, which can be used only for encryption (and signing), and a private one, which can be used only for decryption (and signature verification).

The idea is that the party you want to communicate securely with generates such a keypair and sends you the public key over the insecure channel. Since it cannot be used for decryption, it doesn't matter if a third party gets hold of it. Then you use this public key to encrypt the message and send it to the person you want to communicate securely with. That person then uses the secret key they have generated to decrypt the message.

A popular program that implements this process is PGP.