Arnold Reinhold has been involved with password and passphrase security since the mid-1990s. He is the developer of Diceware, RockSalt, CipherSaber and HEKS, the first password hash designed to consume memory resources as well as CPU time.

He has worked on spacecraft navigation at NASA, apparel industry automation at Marcon, computer-aided design software at Computervision Corp. and helped found Automatix Inc., an early robotics and machine vision company. Mr. Reinhold is co-author of several For Dummies books, including The Internet For Dummies Quick Reference and Email For Dummies, and contributes regularly to Wikipedia. Mr. Reinhold studied mathematics at MIT and management at Harvard.