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	* lib/securerandom.rb (SecureRandom.gen_random): separate implementation details and select at the load time. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48334 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
		
			
				
	
	
		
			293 lines
		
	
	
	
		
			9.2 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
			
		
		
	
	
			293 lines
		
	
	
	
		
			9.2 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
# -*- coding: us-ascii -*-
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begin
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  require 'openssl'
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rescue LoadError
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end
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# == Secure random number generator interface.
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#
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# This library is an interface for secure random number generator which is
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# suitable for generating session key in HTTP cookies, etc.
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#
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# You can use this library in your application by requiring it:
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#
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#   require 'securerandom'
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#
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# It supports following secure random number generators.
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#
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# * openssl
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# * /dev/urandom
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# * Win32
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#
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# === Examples
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#
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# Hexadecimal string.
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#
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#   require 'securerandom'
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#
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#   p SecureRandom.hex(10) #=> "52750b30ffbc7de3b362"
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#   p SecureRandom.hex(10) #=> "92b15d6c8dc4beb5f559"
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#   p SecureRandom.hex(13) #=> "39b290146bea6ce975c37cfc23"
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#
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# Base64 string.
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#
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#   p SecureRandom.base64(10) #=> "EcmTPZwWRAozdA=="
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#   p SecureRandom.base64(10) #=> "KO1nIU+p9DKxGg=="
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#   p SecureRandom.base64(12) #=> "7kJSM/MzBJI+75j8"
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#
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# Binary string.
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#
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#   p SecureRandom.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
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#   p SecureRandom.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
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module SecureRandom
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  if /mswin|mingw/ =~ RUBY_PLATFORM
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    require "fiddle/import"
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    module AdvApi32 # :nodoc:
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      extend Fiddle::Importer
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      dlload "advapi32"
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      extern "int CryptAcquireContext(void*, void*, void*, unsigned long, unsigned long)"
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      extern "int CryptGenRandom(void*, unsigned long, void*)"
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      def self.get_provider
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        hProvStr = " " * Fiddle::SIZEOF_VOIDP
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        prov_rsa_full = 1
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        crypt_verifycontext = 0xF0000000
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        if CryptAcquireContext(hProvStr, nil, nil, prov_rsa_full, crypt_verifycontext) == 0
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          raise SystemCallError, "CryptAcquireContext failed: #{lastWin32ErrorMessage}"
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        end
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        type = Fiddle::SIZEOF_VOIDP == Fiddle::SIZEOF_LONG_LONG ? 'q' : 'l'
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        hProv, = hProvStr.unpack(type)
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        hProv
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      end
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      def self.gen_random(n)
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        @hProv ||= get_provider
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        bytes = " ".force_encoding("ASCII-8BIT") * n
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        if CryptGenRandom(@hProv, bytes.size, bytes) == 0
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          raise SystemCallError, "CryptGenRandom failed: #{Kernel32.last_error_message}"
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        end
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        bytes
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      end
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    end
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    module Kernel32 # :nodoc:
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      extend Fiddle::Importer
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      dlload "kernel32"
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      extern "unsigned long GetLastError()"
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      extern "unsigned long FormatMessageA(unsigned long, void*, unsigned long, unsigned long, void*, unsigned long, void*)"
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      # Following code is based on David Garamond's GUID library for Ruby.
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      def self.last_error_message
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        format_message_ignore_inserts = 0x00000200
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        format_message_from_system    = 0x00001000
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        code = GetLastError()
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        msg = "\0" * 1024
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        len = FormatMessageA(format_message_ignore_inserts + format_message_from_system, 0, code, 0, msg, 1024, nil)
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        msg[0, len].force_encoding("filesystem").tr("\r", '').chomp
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      end
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    end
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  end
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  # SecureRandom.random_bytes generates a random binary string.
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  #
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  # The argument _n_ specifies the length of the result string.
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  #
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  # If _n_ is not specified or is nil, 16 is assumed.
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  # It may be larger in future.
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  #
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  # The result may contain any byte: "\x00" - "\xff".
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  #
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  #   p SecureRandom.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6"
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  #   p SecureRandom.random_bytes #=> "m\xDC\xFC/\a\x00Uf\xB2\xB2P\xBD\xFF6S\x97"
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  #
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  # If secure random number generator is not available,
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  # NotImplementedError is raised.
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  def self.random_bytes(n=nil)
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    n = n ? n.to_int : 16
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    gen_random(n)
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  end
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  if defined? OpenSSL::Random
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    def self.gen_random(n)
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      @pid = 0 unless defined?(@pid)
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      pid = $$
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      unless @pid == pid
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        now = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
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        ary = [now, @pid, pid]
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        OpenSSL::Random.random_add(ary.join("").to_s, 0.0)
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        @pid = pid
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      end
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      return OpenSSL::Random.random_bytes(n)
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    end
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  elsif defined?(AdvApi32)
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    def self.gen_random(n)
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      return AdvApi32.gen_random(n)
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    end
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    def self.lastWin32ErrorMessage # :nodoc:
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      # for compatibility
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      return Kernel32.last_error_message
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    end
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  else
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    def self.gen_random(n)
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      flags = File::RDONLY
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      flags |= File::NONBLOCK if defined? File::NONBLOCK
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      flags |= File::NOCTTY if defined? File::NOCTTY
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      begin
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        File.open("/dev/urandom", flags) {|f|
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          unless f.stat.chardev?
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            break
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          end
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          ret = f.read(n)
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          unless ret.length == n
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            raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
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          end
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          return ret
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        }
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      rescue Errno::ENOENT
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      end
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      raise NotImplementedError, "No random device"
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    end
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  end
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  # SecureRandom.hex generates a random hexadecimal string.
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  #
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  # The argument _n_ specifies the length, in bytes, of the random number to be generated.
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  # The length of the resulting hexadecimal string is twice _n_.
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  #
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  # If _n_ is not specified or is nil, 16 is assumed.
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  # It may be larger in future.
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  #
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  # The result may contain 0-9 and a-f.
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  #
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  #   p SecureRandom.hex #=> "eb693ec8252cd630102fd0d0fb7c3485"
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  #   p SecureRandom.hex #=> "91dc3bfb4de5b11d029d376634589b61"
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  #
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  # If secure random number generator is not available,
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  # NotImplementedError is raised.
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  def self.hex(n=nil)
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    random_bytes(n).unpack("H*")[0]
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  end
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  # SecureRandom.base64 generates a random base64 string.
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  #
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  # The argument _n_ specifies the length, in bytes, of the random number
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  # to be generated. The length of the result string is about 4/3 of _n_.
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  #
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  # If _n_ is not specified or is nil, 16 is assumed.
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  # It may be larger in future.
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  #
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  # The result may contain A-Z, a-z, 0-9, "+", "/" and "=".
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  #
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  #   p SecureRandom.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A=="
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  #   p SecureRandom.base64 #=> "6BbW0pxO0YENxn38HMUbcQ=="
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  #
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  # If secure random number generator is not available,
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  # NotImplementedError is raised.
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  #
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  # See RFC 3548 for the definition of base64.
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  def self.base64(n=nil)
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    [random_bytes(n)].pack("m*").delete("\n")
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  end
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  # SecureRandom.urlsafe_base64 generates a random URL-safe base64 string.
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  #
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  # The argument _n_ specifies the length, in bytes, of the random number
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  # to be generated. The length of the result string is about 4/3 of _n_.
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  #
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  # If _n_ is not specified or is nil, 16 is assumed.
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  # It may be larger in future.
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  #
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  # The boolean argument _padding_ specifies the padding.
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  # If it is false or nil, padding is not generated.
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  # Otherwise padding is generated.
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  # By default, padding is not generated because "=" may be used as a URL delimiter.
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  #
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  # The result may contain A-Z, a-z, 0-9, "-" and "_".
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  # "=" is also used if _padding_ is true.
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  #
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  #   p SecureRandom.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg"
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  #   p SecureRandom.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg"
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  #
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  #   p SecureRandom.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ=="
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  #   p SecureRandom.urlsafe_base64(nil, true) #=> "-M8rLhr7JEpJlqFGUMmOxg=="
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  #
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  # If secure random number generator is not available,
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  # NotImplementedError is raised.
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  #
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  # See RFC 3548 for the definition of URL-safe base64.
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  def self.urlsafe_base64(n=nil, padding=false)
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    s = [random_bytes(n)].pack("m*")
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    s.delete!("\n")
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    s.tr!("+/", "-_")
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    s.delete!("=") unless padding
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    s
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  end
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  # SecureRandom.random_number generates a random number.
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  #
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  # If a positive integer is given as _n_,
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  # SecureRandom.random_number returns an integer:
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  # 0 <= SecureRandom.random_number(n) < n.
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  #
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  #   p SecureRandom.random_number(100) #=> 15
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  #   p SecureRandom.random_number(100) #=> 88
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  #
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  # If 0 is given or an argument is not given,
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  # SecureRandom.random_number returns a float:
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  # 0.0 <= SecureRandom.random_number() < 1.0.
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  #
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  #   p SecureRandom.random_number #=> 0.596506046187744
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  #   p SecureRandom.random_number #=> 0.350621695741409
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  #
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  def self.random_number(n=0)
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    if 0 < n
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      if defined? OpenSSL::BN
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        OpenSSL::BN.rand_range(n).to_i
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      else
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        hex = n.to_s(16)
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        hex = '0' + hex if (hex.length & 1) == 1
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        bin = [hex].pack("H*")
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        mask = bin[0].ord
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        mask |= mask >> 1
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        mask |= mask >> 2
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        mask |= mask >> 4
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        begin
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          rnd = SecureRandom.random_bytes(bin.length)
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          rnd[0] = (rnd[0].ord & mask).chr
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        end until rnd < bin
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        rnd.unpack("H*")[0].hex
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      end
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    else
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      # assumption: Float::MANT_DIG <= 64
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      if defined? OpenSSL::BN
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        i64 = OpenSSL::BN.rand(64, -1).to_i
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      else
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        i64 = SecureRandom.random_bytes(8).unpack("Q")[0]
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      end
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      Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG)
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    end
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  end
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  # SecureRandom.uuid generates a v4 random UUID (Universally Unique IDentifier).
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  #
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  #   p SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
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  #   p SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
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  #   p SecureRandom.uuid #=> "62936e70-1815-439b-bf89-8492855a7e6b"
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  #
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  # The version 4 UUID is purely random (except the version).
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  # It doesn't contain meaningful information such as MAC address, time, etc.
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  #
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  # See RFC 4122 for details of UUID.
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  #
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  def self.uuid
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    ary = self.random_bytes(16).unpack("NnnnnN")
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    ary[2] = (ary[2] & 0x0fff) | 0x4000
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    ary[3] = (ary[3] & 0x3fff) | 0x8000
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    "%08x-%04x-%04x-%04x-%04x%08x" % ary
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  end
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end
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