SpoC: an authenticated cipher

SpoC (pronounced as Spock) stands for Sponge with masked Capacity, is an authenticated encryption with associated data. It is a joint collaboration between the Communication Security (ComSec) laboratory of the University of Waterloo and the Indian Statistical Institute (ISI). SpoC is designed by Riham AlTawy, Guang Gong, Morgan He, Ashwin Jha, Kalikinkar Mandal, Mridul Nandi, and Raghvendra Rohit. The mode of operation adopted in SpoC provides higher security guarantees, thus relaxing the constraints on the state size of the underlying permutation. SpoC provides 128-bit security using 192-bit permutation which is further built using two of the most efficient and well cryptanalyzed constructions, namely, Generalized Feistel Structure (GFS) Type II and the Simeck/Simon round function. What distinguished SpoC from other Spong-based designs is that the capacity is masked with data blocks instead of rate which improves the security and allows larger rate value per permutation call. The underlying permutation is sLiSCP-light which is efficient in both hardware and software because of bitwise and cyclic shift operations. Our most compact ASIC implementation of SpoC has an area of 2329 GE in ASIC CMOS 65nm and achieves a throughput of 58.3 kbps for 1KB message.

Security analysis

• On the Security of Sponge-type Authenticated Encryption Mode.  Chakraborty et al. Cryptology eprint report 2019/1475.

Contact

Should you have any question or feedback, please do not hesitate to contact us. Email: raghvendra-singh.rohit@irisa.fr.