The 4th International Conference on Provable Security (ProvSec) was held in Hotel Equatorial, Malacca, Malaysia, 13-15, October 2010. There were about 40 participants. The topics included were mainly provable secure cryptosystems, e.g. PKE, Key Exchange, Proxy Re-encryption, Broadcast Encryption, Undeniable Signature and so on. The invited talk, entitled Cryptographic Protocols from Lattices, was presented by Eike Kiltz (CWI, the Netherlands). He talked about HB (Hopper-Blum) authentication families. In the conference, the Malacca Heritage Trail was arranged as a half-day tour. ProvSec2011 will be held in Xi'an, China.