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Instance Public methods

authenticate_by(attributes)

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.

Examples

class User < ActiveRecord::Base
  has_secure_password
end

User.create(name: "John Doe", email: "jdoe@example.com", password: "abc123")

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

User.authenticate_by(email: "jdoe@example.com") # => ArgumentError
User.authenticate_by(password: "abc123")        # => ArgumentError
# File activerecord/lib/active_record/secure_password.rb, line 38
def authenticate_by(attributes)
  passwords, identifiers = attributes.to_h.partition do |name, value|
    !has_attribute?(name) && has_attribute?("#{name}_digest")
  end.map(&:to_h)

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

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