Skip to Content Skip to Search

module ActiveRecord::SecurePassword::ClassMethods

Public instance methods

Given a set of attributes, finds a record using the non-password attributes, and then authenticates that record using the password attributes. Returns the record if authentication succeeds; otherwise, returns nil.

Regardless of whether a record is found, authenticate_by will cryptographically digest the given password attributes. This behavior helps mitigate timing-based enumeration attacks, wherein an attacker can determine if a passworded record exists even without knowing the password.

Raises an ArgumentError if the set of attributes doesn’t contain at least one password and one non-password attribute.


class User < ActiveRecord::Base

User.create(name: "John Doe", email: "", password: "abc123")

User.authenticate_by(email: "", password: "abc123").name # => "John Doe" (in 373.4ms)
User.authenticate_by(email: "", password: "wrong")       # => nil (in 373.9ms)
User.authenticate_by(email: "", password: "abc123")     # => nil (in 373.6ms)

User.authenticate_by(email: "", password: nil) # => nil (no queries executed)
User.authenticate_by(email: "", password: "")  # => nil (no queries executed)

User.authenticate_by(email: "") # => ArgumentError
User.authenticate_by(password: "abc123")        # => ArgumentError
Source code GitHub
# File activerecord/lib/active_record/secure_password.rb, line 41
def authenticate_by(attributes)
  passwords, identifiers = attributes.to_h.partition do |name, value|
    !has_attribute?(name) && has_attribute?("#{name}_digest")

  raise ArgumentError, "One or more password arguments are required" if passwords.empty?
  raise ArgumentError, "One or more finder arguments are required" if identifiers.empty?

  return if passwords.any? { |name, value| value.nil? || value.empty? }

  if record = find_by(identifiers)
    record if passwords.count { |name, value| record.public_send(:"authenticate_#{name}", value) } == passwords.size

Definition files