Fixing a 1-in-256 bug in CLWW order-preserving encryption

Many databases let you sort and range-query encrypted data using order-preserving encryption (OPE): a scheme where ciphertext bytes compare in the same order as their plaintexts, so standard B-tree indexes and ORDER BY clauses Just Work. A well-known construction is Chenette-Lewi-Weis-Wu (CLWW) from 2015 — small, fast, and widely deployed. The paper gives an order- revealing scheme with a custom comparator, and notes in passing that the same ciphertext bytes can be compared lexicographically to