The stanford IBE library is a C implementation of the Boneh-Franklin
identity-based encryption scheme. (See Boneh and Franklin, "Identity-Based
Encryption from the Weil Pairing", CRYPTO 2001.)
There are a few modifications and additions. The Boneh-Franklin scheme is
used as a Key Encapsulation Mechanism, and off-the-shelf ciphers and HMACs
are used for the actual encryption. (See Lynn, "Authenticated Identity-Based
Encryption", available on eprint.