Whiten

Verb

1. (To cause) to become white or whiter; to bleach or blanch.

   "Age had whitened his hair."

2. To increase the security of an iterated block cipher by steps that combine the data with portions of the key.
3. To normalize data so that the covariance matrix becomes the identity matrix; i.e., to remove correlations so each variable has unit variance.<!-- ety: from "white noise"? noun: [[whitening transformation]] syn: [[sphering transformation]] -->