hyoon_cryptography

• Elliptic Curve Cryptosystem

Cryptosystems based on elliptic curves are an exciting technology because for the same level of security as systems such as RSA, using the current knowledge of algorithms, they offer the benefits of smaller key sizes and hence of smaller memory and processor requirements. This makes them ideal for use in smart cards, mobile devices and other environments where resources such as storage, time, or power are at a premium.

• ID Based Cryptosystem

Identity-based Encryption is a form of public key encryption for which the public key can be an arbitrary string, and in particular, a string that identifies the user who holds the associated private key, like his email address. The original motivation for identity-based cryptography was to simplify certificate management, but it has many other applications.

• Group Communication

Secure group communication, which will become a critical networking issue in the near future, provides confidentiality, authenticity and integrity of messages delivered between group members. Its main issues are scalability, reasonable computation cost and network cost.

• Broadcast Encryption

The area of broadcast encryption deals with methods to efficiently broadcast information to a dynamically changing group of users who are allowed to receive the data. In contrast with secure group communication, allowed receivers are not whole group members but only selected members.

• Threshold Cryptosystem

The idea of a threshold cryptosystem is to remove single point of failure by distributing secret-key operation among a group of servers. The goal of a threshold cryptosystem is to design this distributed implementation of the secret-key operation in such a way that the cryptosystem remains secure in the presence of adversaries that can break into, spy on, disconnect , crash, or in any other way corrupt some of the participating servers, as long as the number of such corrupted servers is smaller than certain threshold.

• Application of Digital Signature

Key-evolving signature scheme - The key evolving scheme is proposed for minimizing the damage of key exposure, the practical threats to security of cryptographic schemes. To limit the damage, the key evolving scheme splits the time for which the signature is valid into well defined short periods. The secret key can then evolve with the periods, while maintaining the same public key.

Proxy signature scheme - The proxy signature scheme is a method for an entity to delegate signing capabilities to other participants to be able to sign on behalf of the entity within given context. The notion is motivated by real life flexibility of "power of attorney" and other mechanisms of proxy.

• Software Security

Software security is to protect S/W against illegitimate modifications by its user. Protection of S/W execution in an insecure environment assures that the S/W will execute as expected.