Key encapsulation mechanisms (KEMs) are a class of encryption techniques designed to secure symmetric cryptographic key material for transmission using asymmetric (public-key) algorithms. In practice, public key systems are clumsy to use in transmitting long messages. Instead they are often used to exchange symmetric keys, which are relatively short. The symmetric key is then used to encrypt the longer message.
The traditional approach to sending a symmetric key with public key systems is to first generate a random symmetric key and then encrypt it using the chosen public key algorithm. The recipient then decrypts the public key message to recover the symmetric key. As the symmetric key is generally short, padding is required for full security and proofs of security for padding schemes are often less than complete. KEMs simplify the process by generating a random element in the finite group underlying the public key system and deriving the symmetric key by hashing that element, eliminating the need for padding.
Read more about Key Encapsulation: Example Using RSA Encryption
Famous quotes containing the word key:
“The key to the age may be this, or that, or the other, as the young orators describe; the key to all ages is—Imbecility: imbecility in the vast majority of men, at all times, and even in heroes, in all but certain eminent moments: victims of gravity, customs and fear. This gives force to the strong,—that the multitude have no habit of self-reliance or original action.”
—Ralph Waldo Emerson (1803–1882)