Symmetric Cryptography

Summary

Cryptography is the science that studies secure communication in adversarial environments. Symmetric Cryptography deals with two cases:

• either sender and receiver share the same secret key, as for encryption and message authentication;
• or neither sender nor receiver use any key at all, as, e.g., in the case of cryptographic hash functions.

Specifically, Symmetric Cryptography deals with symmetric primitives (block and stream ciphers, message authentication codes and hash functions), and complex cryptosystems and cryptographic protocols employing these primitives.

Since symmetric cryptosystems are one to two orders of magnitude more efficient than asymmetric systems, most security applications use symmetric cryptography to ensure the privacy, the authenticity and the integrity of sensitive data. Even most applications of public-key cryptography are actually working in a hybrid way, separating an asymmetric protocol layer for key transmission or key agreement from secure payload transmission by symmetric techniques.

The seminar brought together about 40 researchers from industry and academia, leading experts as well as exceptionally talented junior researchers. Most of the presentations did concentrate on one of the following three research directions:

• studying the design and analysis of stream ciphers
• presenting and attacking recent proposals for cryptographic hash functions; and
• advancing the field of complex symmetric cryptosystems and protocols and their provable security.

Research in Symmetric Cryptography is quickly evolving. The seminar was the second of its kind, the first one took place in 2007. We observe a steadily increasing interest in Symmetric Cryptography, as well as a growing practical demand for symmetric algorithms and protocols.

The seminar was very successful in discussing recent results and sharing new ideas. Furthermore, it inspired the participants to consider how Symmetric Cryptography has evolved in the past, and how they would like it to evolve in the future. The hospitality and support of the Dagstuhl team did contribute significantly to the success of the seminar.