Password Validation

From: here

• Users must supply a passphrase when signing up
  
• Passphrases should be between 8 and 64 characters in length
  
• It is not necessary to supply a passphrase when updating an existing record
  
• Confirmation must be supplied when setting a new passphrase on an existing record
  

These requirements lead to the following validations:

  MINIMUM_PASSPHRASE_LENGTH     = 8
 MAXIMUM_PASSPHRASE_LENGTH     = 64

 validates_presence_of         :passphrase,
                               :on         => :create
 validates_length_of           :passphrase,
                               :in         => MINIMUM_PASSPHRASE_LENGTH..MAXIMUM_PASSPHRASE_LENGTH,
                               :if         => Proc.new { |u| !u.passphrase.blank? }
 validates_confirmation_of     :passphrase,
                               :if         => Proc.new { |u| !u.passphrase.blank? }