Cryptography Reference
In-Depth Information
The encryption speed of the proposed design is of the same order as that of
the original HC-128. Also observe that the extra array element access in the
new update rules (Equation (10.20)) as compared to the original update rules
does not affect the performance much. HC-128 was designed as a lightweight
version of HC-256. The idea of cross-referencing each other in the update rules
of P and Q has also been used in the design of HC-256 and that is why the half
state exposure does not reveal the full state in case of HC-256. However, the
modification to HC-128 removes the known weaknesses of HC-128 but keeps
the speed much better than HC-256, with only a little reduction in speed
compared to HC-128.
RESEARCH PROBLEMS
Problem 10.1 Is there a distinguishing attack on HC-128, that requires less
than 2
128
keystream words?
Problem 10.2 Check the feasibility of a state recovery attack on HC-128.
Problem 10.3 Do a parallelized implementation of HC-128 and estimate the
improvement in speed.
