Public Key Encryption


What is public key encryption?

Public key encryption involves using separate keys for encryption and decryption. The sender and the recipient must have the same software. The recipient makes a pair of keys – public key and private key (both keys can be unlocked with a single password). Public key can be used by anyone with the same software to encrypt a message. Public keys can be freely distributed without worrying since it is only used to scramble (encrypt) the data.
The sender does not need the recipient’s password to use his or her public key to encrypt data. The recipient’s other key is a private key that only he or she can use when decrypting the message. Private key should never be distributed since the private key assures that only the intended recipient can unscramble (decrypt) data intended for him or her. The recipient can freely distribute the public key without worrying since it is only used to scramble the data.

Public key encryption algorithms:
– RSA
– DSA
– PGP 

Public key and private key encryption

Public key encryption algorithms encrypt and decrypt with different keys. Data is encrypted with a public key, and decrypted with a private key. Public key encryption algorithms are incredibly slow and it is impractical to use them to encrypt large amounts of data.
Private key encryption algorithms encrypt and decrypt with the same key. Their main advantages are security and high speed. Generally, private key encryption algorithms are much faster to execute on a computer than public key ones. In practice they could be used together, so that a public-key algorithm is used to encrypt a randomly generated encryption key, and the random key is used to encrypt the actual message using a private key algorithm.