# -*- coding: us-ascii -*- # frozen_string_literal: true # == Secure random number generator interface. # # This library is an interface to secure random number generators which are # suitable for generating session keys in HTTP cookies, etc. # # You can use this library in your application by requiring it: # # require 'securerandom' # # It supports the following secure random number generators: # # * openssl # * /dev/urandom # * Win32 # # SecureRandom is extended by the Random::Formatter module which # defines the following methods: # # * alphanumeric # * base64 # * choose # * gen_random # * hex # * rand # * random_bytes # * random_number # * urlsafe_base64 # * uuid # # These methods are usable as class methods of SecureRandom such as # `SecureRandom.hex`. # # === Examples # # Generate random hexadecimal strings: # # require 'securerandom' # # SecureRandom.hex(10) #=> "52750b30ffbc7de3b362" # SecureRandom.hex(10) #=> "92b15d6c8dc4beb5f559" # SecureRandom.hex(13) #=> "39b290146bea6ce975c37cfc23" # # Generate random base64 strings: # # SecureRandom.base64(10) #=> "EcmTPZwWRAozdA==" # SecureRandom.base64(10) #=> "KO1nIU+p9DKxGg==" # SecureRandom.base64(12) #=> "7kJSM/MzBJI+75j8" # # Generate random binary strings: # # SecureRandom.random_bytes(10) #=> "\016\t{\370g\310pbr\301" # SecureRandom.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337" # # Generate alphanumeric strings: # # SecureRandom.alphanumeric(10) #=> "S8baxMJnPl" # SecureRandom.alphanumeric(10) #=> "aOxAg8BAJe" # # Generate UUIDs: # # SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594" # SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab" # module SecureRandom class << self def bytes(n) return gen_random(n) end private def gen_random_openssl(n) @pid = 0 unless defined?(@pid) pid = $$ unless @pid == pid now = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond) OpenSSL::Random.random_add([now, @pid, pid].join(""), 0.0) seed = Random.urandom(16) if (seed) OpenSSL::Random.random_add(seed, 16) end @pid = pid end return OpenSSL::Random.random_bytes(n) end def gen_random_urandom(n) ret = Random.urandom(n) unless ret raise NotImplementedError, "No random device" end unless ret.length == n raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes" end ret end ret = Random.urandom(1) if ret.nil? begin require 'openssl' rescue NoMethodError raise NotImplementedError, "No random device" else alias gen_random gen_random_openssl end else alias gen_random gen_random_urandom end public :gen_random end end module Random::Formatter # SecureRandom.random_bytes generates a random binary string. # # The argument _n_ specifies the length of the result string. # # If _n_ is not specified or is nil, 16 is assumed. # It may be larger in future. # # The result may contain any byte: "\x00" - "\xff". # # require 'securerandom' # # SecureRandom.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6" # SecureRandom.random_bytes #=> "m\xDC\xFC/\a\x00Uf\xB2\xB2P\xBD\xFF6S\x97" # # If a secure random number generator is not available, # +NotImplementedError+ is raised. def random_bytes(n=nil) n = n ? n.to_int : 16 gen_random(n) end # SecureRandom.hex generates a random hexadecimal string. # # The argument _n_ specifies the length, in bytes, of the random number to be generated. # The length of the resulting hexadecimal string is twice of _n_. # # If _n_ is not specified or is nil, 16 is assumed. # It may be larger in the future. # # The result may contain 0-9 and a-f. # # require 'securerandom' # # SecureRandom.hex #=> "eb693ec8252cd630102fd0d0fb7c3485" # SecureRandom.hex #=> "91dc3bfb4de5b11d029d376634589b61" # # If a secure random number generator is not available, # +NotImplementedError+ is raised. def hex(n=nil) random_bytes(n).unpack("H*")[0] end # SecureRandom.base64 generates a random base64 string. # # The argument _n_ specifies the length, in bytes, of the random number # to be generated. The length of the result string is about 4/3 of _n_. # # If _n_ is not specified or is nil, 16 is assumed. # It may be larger in the future. # # The result may contain A-Z, a-z, 0-9, "+", "/" and "=". # # require 'securerandom' # # SecureRandom.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A==" # SecureRandom.base64 #=> "6BbW0pxO0YENxn38HMUbcQ==" # # If a secure random number generator is not available, # +NotImplementedError+ is raised. # # See RFC 3548 for the definition of base64. def base64(n=nil) [random_bytes(n)].pack("m0") end # SecureRandom.urlsafe_base64 generates a random URL-safe base64 string. # # The argument _n_ specifies the length, in bytes, of the random number # to be generated. The length of the result string is about 4/3 of _n_. # # If _n_ is not specified or is nil, 16 is assumed. # It may be larger in the future. # # The boolean argument _padding_ specifies the padding. # If it is false or nil, padding is not generated. # Otherwise padding is generated. # By default, padding is not generated because "=" may be used as a URL delimiter. # # The result may contain A-Z, a-z, 0-9, "-" and "_". # "=" is also used if _padding_ is true. # # require 'securerandom' # # SecureRandom.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg" # SecureRandom.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg" # # SecureRandom.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ==" # SecureRandom.urlsafe_base64(nil, true) #=> "-M8rLhr7JEpJlqFGUMmOxg==" # # If a secure random number generator is not available, # +NotImplementedError+ is raised. # # See RFC 3548 for the definition of URL-safe base64. def urlsafe_base64(n=nil, padding=false) s = [random_bytes(n)].pack("m0") s.tr!("+/", "-_") s.delete!("=") unless padding s end # SecureRandom.uuid generates a random v4 UUID (Universally Unique IDentifier). # # require 'securerandom' # # SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594" # SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab" # SecureRandom.uuid #=> "62936e70-1815-439b-bf89-8492855a7e6b" # # The version 4 UUID is purely random (except the version). # It doesn't contain meaningful information such as MAC addresses, timestamps, etc. # # The result contains 122 random bits (15.25 random bytes). # # See RFC 4122 for details of UUID. # def uuid ary = random_bytes(16).unpack("NnnnnN") ary[2] = (ary[2] & 0x0fff) | 0x4000 ary[3] = (ary[3] & 0x3fff) | 0x8000 "%08x-%04x-%04x-%04x-%04x%08x" % ary end private def gen_random(n) self.bytes(n) end # SecureRandom.choose generates a string that randomly draws from a # source array of characters. # # The argument _source_ specifies the array of characters from which # to generate the string. # The argument _n_ specifies the length, in characters, of the string to be # generated. # # The result may contain whatever characters are in the source array. # # require 'securerandom' # # SecureRandom.choose([*'l'..'r'], 16) #=> "lmrqpoonmmlqlron" # SecureRandom.choose([*'0'..'9'], 5) #=> "27309" # # If a secure random number generator is not available, # +NotImplementedError+ is raised. private def choose(source, n) size = source.size m = 1 limit = size while limit * size <= 0x100000000 limit *= size m += 1 end result = ''.dup while m <= n rs = random_number(limit) is = rs.digits(size) (m-is.length).times { is << 0 } result << source.values_at(*is).join('') n -= m end if 0 < n rs = random_number(limit) is = rs.digits(size) if is.length < n (n-is.length).times { is << 0 } else is.pop while n < is.length end result.concat source.values_at(*is).join('') end result end ALPHANUMERIC = [*'A'..'Z', *'a'..'z', *'0'..'9'] # SecureRandom.alphanumeric generates a random alphanumeric string. # # The argument _n_ specifies the length, in characters, of the alphanumeric # string to be generated. # # If _n_ is not specified or is nil, 16 is assumed. # It may be larger in the future. # # The result may contain A-Z, a-z and 0-9. # # require 'securerandom' # # SecureRandom.alphanumeric #=> "2BuBuLf3WfSKyQbR" # SecureRandom.alphanumeric(10) #=> "i6K93NdqiH" # # If a secure random number generator is not available, # +NotImplementedError+ is raised. def alphanumeric(n=nil) n = 16 if n.nil? choose(ALPHANUMERIC, n) end end SecureRandom.extend(Random::Formatter)