Pairing-based cryptography is based on pairing functions that map pairs of points on an elliptic curve into a finite field. The unique properties of these pairing functions have enabled many new cryptographic protocols that had not been previously feasible.
Pairings are useful in cryptography because if constructed properly, they can produce finite fields that are large enough to make the discrete logarithm problem hard to compute, but small enough to make computations efficient.
Pairing-based cryptography has been used to construct identity-based encryption (IBE), which allows a sender to encrypt a message without needing a receiver’s public key to have been certified and distributed in advance. IBE uses some form of a person (or entity’s) identification to generate a public key. This could be an email address, for instance. Besides IBE, there are a number of other applications of pairing-based cryptography, including other identity-based cryptosystems and signature schemes, key establishment schemes, functional and attribute-based encryption, and privacy-enhancing techniques, such as the use of anonymous credentials.