ActiveSupport::SecurityUtils
Methods
S
Class Public methods
secure_compare(a, b)

Constant time string comparison.

The values compared should be of fixed length, such as strings that have already been processed by HMAC. This should not be used on variable length plaintext strings because it could leak length info via timing attacks.

Source: show | on GitHub 

# File activesupport/lib/active_support/security_utils.rb, line 11
def secure_compare(a, b)
  return false unless a.bytesize == b.bytesize

  l = a.unpack "C#{a.bytesize}"

  res = 0
  b.each_byte { |byte| res |= byte ^ l.shift }
  res == 0
end