2. Brand-New Hash Function   BeeM A. Satoh

3. SCIS2006 SHA-1 Broken! Prof. Xiaoyun Wang

4. SCIS2006 Essential Characteristics of Hash Function  Hash Function –Algorithm that compresses an arbitrarily size of message into a fixed size hash value. It is also called a message digest function. –Used for authentication, error detection, and pseudo-random number generators  One-Wayness –It is easy to generate the hash value from a given message, but it is computationally infeasible to generate a message producing a given hash value.  Collision Resistance –It is computationally infeasible to generate a message pair that has the same hash value.

5. SCIS2006 Birthday Attack  In a group of 40 people, a pair who have the same birthday can be found with 89% probability  When a hash value size is n bits, a collision can be found in 2 n/2 messages with 50% probability Birthday Paradox

6. SCIS2006 Example One- wayness is also satisfied Collision Resistan ce against Birthday Attack Birthday Brand-New Hash Function

7. SCIS2006 Bye-Bye My Love