International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Ramesh Karri

Publications

Year
Venue
Title
2014
EPRINT
2005
EPRINT
A High Speed Architecture for Galois/Counter Mode of Operation (GCM)
Bo Yang Sambit Mishra Ramesh Karri
In this paper we present a fully pipelined high speed hardware architecture for Galois/Counter Mode of Operation (GCM) by analyzing the data dependencies in the GCM algorithm at the architecture level. We show that GCM encryption circuit and GCM authentication circuit have similar critical path delays resulting in an efficient pipeline structure. The proposed GCM architecture yields a throughput of 34 Gbps running at 271 MHz using a 0.18 um CMOS standard cell library.
2004
CHES
2004
EPRINT
Scan Based Side Channel Attack on Data Encryption Standard
Bo Yang Kaijie Wu Ramesh Karri
Scan based test is a double edged sword. On one hand, it is a powerful test technique. On the other hand, it is an equally powerful attack tool. In this paper we show that scan chains can be used as a side channel to recover secret keys from a hardware implementation of the Data Encryption Standard (DES). By loading pairs of known plaintexts with one-bit difference in the normal mode and then scanning out the internal state in the test mode, we first determine the position of all scan elements in the scan chain. Then, based on a systematic analysis of the structure of the non-linear substitution boxes, and using three additional plaintexts we discover the DES secret key. Finally, some assumptions in the attack are discussed.
2003
CHES
2003
EPRINT
Divide and Concatenate: A Scalable Hardware Architecture for Universal MAC
Bo Yang Ramesh Karri David Mcgrew
We present a cryptographic architecture optimization technique called divide-and-concatenate based on two observations: (i) the area of a multiplier and associated data path decreases exponentially and their speeds increase linearly as their operand size is reduced. (ii) in hash functions, message authentication codes and related cryptographic algorithms, two functions are equivalent if they have the same collision probability property. In the proposed approach we divide a 2w-bit data path (with collision probability 2-2w) into two w-bit data paths (each with collision probability 2-w) and concatenate their results to construct an equivalent 2w-bit data path (with a collision probability 2-2w). We applied this technique on NH hash, a universal hash function that uses multiplications and additions. When compared to the 100% overhead associated with duplicating a straightforward 32-bit pipelined NH hash data path, the divide-and-concatenate approach yields a 94% increase in throughput with only 40% hardware overhead. The NH hash associated message authentication code UMAC architecture with collision probability 2-32 that uses four equivalent 8-bit divide-and-concatenate NH hash data paths yields a throughput of 79.2 Gbps with only 3840 FPGA slices when implemented on a Xilinx XC2VP7-7 Field Programmable Gate Array (FPGA).