pub struct Hc128Rng(_);
A cryptographically secure random number generator that uses the HC-128 algorithm.
HC-128 is an array based RNG. In this it is similar to RC-4 and ISAAC before it, but those have never been proven cryptographically secure (or have even been significantly compromised, as in the case of RC-43).
Because HC-128 works with simple indexing into a large array and with a few operations that parallelize well, it has very good performance. The size of the array it needs, 4kb, can however be a disadvantage.
This implementation is not based on the version of HC-128 submitted to the eSTREAM contest, but on a later version by the author with a few small improvements from December 15, 20094.
HC-128 has no known weaknesses that are easier to exploit than doing a brute-force search of 2128. A very comprehensive analysis of the current state of known attacks / weaknesses of HC-128 is given in Some Results On Analysis And Implementation Of HC-128 Stream Cipher5.
The average cycle length is expected to be 21024*32+10-1 = 232777. We support seeding with a 256-bit array, which matches the 128-bit key concatenated with a 128-bit IV from the stream cipher.
Shashwat Raizada (January 2015),“Some Results On Analysis And Implementation Of HC-128 Stream Cipher”. ↩
Returns the argument unchanged.