has_secure_password

Adds methods to set and authenticate against a BCrypt password. This mechanism requires you to have a password_digest attribute.

Validations for presence of password on create, confirmation of password (using a password_confirmation attribute) are automatically added. If you wish to turn off validations, pass validations: false as an argument. You can add more validations by hand if need be.

If you don’t need the confirmation validation, just don’t set any value to the password_confirmation attribute and the validation will not be triggered.

You need to add bcrypt (~> 3.1.7) to Gemfile to use #has_secure_password:

gem 'bcrypt', '~> 3.1.7'

Example using Active Record (which automatically includes ActiveModel::SecurePassword):

# Schema: User(name:string, password_digest:string)
class User < ActiveRecord::Base
  has_secure_password
end

user = User.new(name: 'david', password: '', password_confirmation: 'nomatch')
user.save                                                       # => false, password required
user.password = 'mUc3m00RsqyRe'
user.save                                                       # => false, confirmation doesn't match
user.password_confirmation = 'mUc3m00RsqyRe'
user.save                                                       # => true
user.authenticate('notright')                                   # => false
user.authenticate('mUc3m00RsqyRe')                              # => user
User.find_by(name: 'david').try(:authenticate, 'notright')      # => false
User.find_by(name: 'david').try(:authenticate, 'mUc3m00RsqyRe') # => user