Posed as an open problem in 1984, but efficiently instantiated only in 2001, identity-based encryption hasn't left the forefront of cryptographic research since. Praised by fans as the economical alternative to public-key infrastructures, booed by critics for its inherent key escrow, identity-based cryptography is also the topic of numerous debates in the cryptographic community. Identity-Based Cryptography looks beyond the controversy and intends to give an overview of the current state-of-the-art in identity-based cryptography. Since research on the topic is still actively continuing, this is necessarily a snapshot of a field in motion, rather than the final word about it. Still, the authors felt the main concepts have by now sufficiently matured to collect them in a single dedicated volume.