Abstract: 

In the past years significant progress was made in privacy preserving cryptography making zero-knowledge proof (ZKP), multiparty computation (MPC) and homomorphic encryption (HE) practical or nearly practical for real-world applications like secure key storage, anonymous cryptocurrencies, private machine learning etc.

Block ciphers and hash functions are symmetric key (SK) primitives that play an important role for providing data security in this newly emerging and dynamic area of modern cryptography and its applications. However, SK primitives once developed for classical applications where data in transit is secured (e.g. TLS), pose an efficiency bottleneck for this new class of cryptographic applications where data under computation has to be secured.

In this talk I will discuss the performance requirements of SK primitives that are dictated by privacy preserving cryptography, and the new approaches in SK cryptography to solve the above-mentioned inefficiency bottleneck. I will describe how new types of SK primitives can significantly improve efficiency compared to their classical counter-parts like AES and SHA-2. I will show examples of such novel SK primitives, their efficiency gain (over classical primitives) and usage in real-world applications. I will also explain how the design and cryptanalysis of these new types of SK primitives pose interesting and new mathematical challenges that have not been encountered thus far and have not been decisive in developing their classical counter-parts.