The 10th International Workshop on Information Security Applications (WISA 2009) was held in Busan, Korea during August 25-27, 2009. The workshop was hosted by the Korea Institute of Information Security and Cryptology (KIISC), supported by the Electronics and Telecommunications Research Institute (ETRI) and the Korea Internet and Security Agency (KISA), sponsored by the Ministry of Public Administration and Security (MoPAS) and the Korea Communications Commission (KCC), financially sponsored by the ST. Ltd. The aim of the workshop was to serve as a forum for presenting new research and experimental results in the area of information security applications from academic communities as well as from industry. The workshop program covered a wide range of security aspects, from cryptography to systems and network security and experimental work as well. It was our great pleasure and honor to serve as the Program Committee Co-chairs of WISA2009. This year, too, the proceedings of the workshop were published in the LNCS series of Springer. The WISA 2009 Program Committee received 79 papers form 16 countries. This year the submissions were exceptionally strong, and the committee accepted 27 papers for the full paper presentation track. All the papers were carefully evaluated through blind peer-review by at least three members of the Program Comm- tee. We would like to say that acceptance is a great achievement since the selection process was highly competitive, and many good papers were not accepted.