Here's a very quick and dirty one for Ruby: require 'zlib' base = "whatever" salt = "whatever" Zlib.crc32(base + salt).to_s(36) This will generate 6-7 char

Here's a very quick and dirty one for Ruby: require 'zlib' base = "whatever" salt = "whatever" Zlib.crc32(base + salt).to_s(36) This will generate 6-7 character strings. Not sure how likely collisions are, but they should be rare enough that a simple check/regenerate should work.