module BCryptPbkdf

   # File lib/bcrypt_pbkdf.rb
20 def self.key(pass,salt,keylen,rounds)
21   BCryptPbkdf::Engine::__bc_crypt_pbkdf(pass,salt,keylen,rounds)
22 end

generates a key from a password + salt returning a string with keylen bytes that can be used as cryptographic key.

Remember to get a good random salt of at least 16 bytes. Using a higher rounds count will increase the cost of an exhaustive search but will also make derivation proportionally slower.

Example:

rounds = 10
keylen = 64
@key = BCryptPbkdf.key("my secret", "my salt", keylen, rounds)