What is "davegrohl"

DaveGrohl is a brute-force password cracker for Mac OS X. It was originally created in 2010 as a password hash extractor but has since evolved into a standalone or distributed password cracker. It supports all of the standard Mac OS X user password hashes ( MD4, SHA-512 and PBKDF2) used since OS X Lion and also can extract them formatted for other popular password crackers like John the Ripper. The latest stable release is designed specifically for Mac OS X Lion and Mountain Lion.