What is Public Key Cryptography?

Public key cryptography (sometimes referred to as asymmetric cryptography) is a class of cryptographic protocols based on algorithms. This method of cryptography requires two separate keys, one that is private or secret, and one that is public. Public key cryptography uses a pair of keys to encrypt and decrypt data to protect it against unauthorized access or use. Network users receive a public and private key pair from certification authorities. If other users want to encrypt data, they get the intended recipient’s public key from a public directory. This key is used to encrypt the message, and to send it to the recipient. When the message arrives, the recipient decrypts it using a private key, to which no one else has access.

The Rivest-Sharmir-Adleman (RSA) algorithm is the cryptography system that is used for public key cryptography, which is commonly used when sending secure, sensitive data over an insecure network like the internet. The RSA algorithm is popular because it allows both public and private keys to encrypt messages so their confidentiality and authenticity remain intact.

Challenges of Public Key Cryptography

Speed often is cited as the most common challenge associated with public key cryptography. Several private key cryptography methods are a great deal faster than the public key encryption method that currently is available. One way of overcoming this challenge with public key cryptography is to combine it with secret key systems to offer the security advantages of the public key system and the speed of the secret (private) key system.

Another challenge associated with public key cryptography is that it has been susceptible to attacks through spoofed or compromised certification authorities. When these attacks take place, cyber criminals impersonate nearly anyone by choosing a public key certificate from the compromised authority. This allows cyber criminals to connect a public key to the name of another user.