HC-256 is a stream cipher designed to provide bulk encryption in software at high speeds while permitting strong confidence in its security.
[1] A 128-bit variant was submitted as an eSTREAM cipher candidate and has been selected as one of the four final contestants in the software profile.
Finally a linear bit-masking function is applied to generate an output word.
[2] The performance of HC-256 is estimated by its author to be about 4 cycles per byte on a Pentium 4 processor.
For HC-128 an encryption speed of about 3 cycles per byte on a Pentium M processor are cited.