ICITS2009washeldattheShizuokaConventionandArtsCenter“GRANSHIP” in Japan during December 3–6,2009.This was the 4th International Conference on Information Theoretic Security. Over the last few decades, we have seen several research topics studied - quiringinformationtheoreticalsecurity,alsocalledunconditionalsecurity,where there is no unproven computational assumption on the adversary. (This is the framework proposed by Claude Shannon in his seminal paper.) Also, coding as well as other aspects of information theory have been used in the design of cryptographic schemes. Examples are authentication, secure communication, key exchange, multi-party computation and information hiding to name a few. A related area is quantum cryptography that predominantly uses information theory for modeling and evaluation of security. Needless to say, information t- oretically secure cryptosystems are secure even if the factoring assumption or the discrete log assumption is broken. Seeing the multitude of topics in m- ern cryptographyrequiring informationtheoreticalsecurity or using information theory, it is time to have a regular conference on this topic. This was the fourth conference of this series, aiming to bring together the leading researchers in the area of information and/or quantum theoretic security.