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'''Public-key encryption''' is an [[encryption]] method in which the encryption key is public. There is a private key used known only to the individual. This differs from the traditional (so-called "private-key") encryption, in which the key is kept secret from the intended recipient. Public-key encryption is a form of ''[[symmetry|asymmetric]] encryption'', meaning that it is much easier to encrypt a message than to decrypt it, at least without knowing the decryption key.

'''Public-key encryption''' is an assymetric [[encryption]] method in which 2 complementary keys are used. What gets encrypted by one of the keys can only be decrypted by the other. Generally one key of the pair is kept safe by an individual and the other key is distributed as widely as possible, after which 2 things can be done.

 

If a message can be decrypted using the widely distributed ("public") key, it proves that the author of the message is the individual that holds the private key. Conversely, if a message is encrypted by the public key, it can only be decrypted by the key that was kept safe (the "private" key), making it possible to send a confidential message to the holder of the private key knowing only the public key. While this is the general principle of operation, many modifications are made in order to ensure practical and quick encryption.

Well-known public-key encryption algorithms include '''Diffie-Hellman''' and '''RSA'''. In Diffie-Hellman, the hardness is based on the [[discrete logarithm]]; in RSA it is [[factoring]].

Well-known public-key encryption algorithms include '''Diffie-Hellman''' and '''RSA'''. In Diffie-Hellman, the hardness is based on the [[discrete logarithm]]; in RSA it is [[factoring]].