There are two types of encryption ciphers: symmetric and asymmetric. Symmetric encryption relies on a single shared key for both encryption and decryption, and preserves confidentiality so long as the shared key remains secret and is unaltered. However, if the shared key is exposed to a third party, the protected information can be decrypted into plaintext, and secrecy is lost. Maintaining the secrecy of the shared key used in symmetric cryptography is therefore critical to maintaining the confidentiality of private information. The Advanced Encryption Standard (AES) is one of the most widely used symmetric algorithms in the world, with key lengths ranging from 128 to 256 bits. AES has been adopted by the US National Institute of Standards and Technology (NIST).

On the other hand, asymmetric encryption uses a complementary pair of keys, one public and one private. Data encrypted by a public key can only be decrypted by its associated private key. Because asymmetric cryptography is much slower than symmetric, these functions are typically limited to encrypting symmetric keys. Once decrypted by the receiver, the symmetric key can then be used to decrypt the rest of the message. The Rivest-Shamir-Adleman suite of algorithms (RSA) and Elliptic-curve Cryptography (ECC) are the two most common families of asymmetric ciphers.