module SecureRandom
Public Class Methods
::base64 generates a random base64 string.
The argument n specifies the length of the random length. The length of the result string is about 4/3 of n.
If n is not specified, 16 is assumed. It may be larger in future.
If secure random number generator is not available, NotImplementedError is raised.
# File lib/compat/securerandom.rb, line 145 def self.base64(n=nil) [random_bytes(n)].pack("m*").delete("\n") end
::hex generates a random hex string.
The argument n specifies the length of the random length. The length of the result string is twice of n.
If n is not specified, 16 is assumed. It may be larger in future.
If secure random number generator is not available, NotImplementedError is raised.
# File lib/compat/securerandom.rb, line 131 def self.hex(n=nil) random_bytes(n).unpack("H*")[0] end
::random_bytes generates a random binary string.
The argument n specifies the length of the result string.
If n is not specified, 16 is assumed. It may be larger in future.
If secure random number generator is not available, NotImplementedError is raised.
# File lib/compat/securerandom.rb, line 52 def self.random_bytes(n=nil) n ||= 16 if defined? OpenSSL::Random return OpenSSL::Random.random_bytes(n) end if !defined?(@has_urandom) || @has_urandom flags = File::RDONLY flags |= File::NONBLOCK if defined? File::NONBLOCK flags |= File::NOCTTY if defined? File::NOCTTY flags |= File::NOFOLLOW if defined? File::NOFOLLOW begin File.open("/dev/urandom", flags) {|f| unless f.stat.chardev? raise Errno::ENOENT end @has_urandom = true ret = f.readpartial(n) if ret.length != n raise NotImplementedError, "Unexpected partial read from random device" end return ret } rescue Errno::ENOENT @has_urandom = false end end if !defined?(@has_win32) begin require 'Win32API' crypt_acquire_context = Win32API.new( "advapi32", "CryptAcquireContext", 'PPPII', 'L' ) @crypt_gen_random = Win32API.new( "advapi32", "CryptGenRandom", 'LIP', 'L' ) hProvStr = " " * 4 prov_rsa_full = 1 crypt_verifycontext = 0xF0000000 if crypt_acquire_context.call( hProvStr, nil, nil, prov_rsa_full, crypt_verifycontext) == 0 raise SystemCallError, "CryptAcquireContext failed: #{lastWin32ErrorMessage}" end @hProv, = hProvStr.unpack('L') @has_win32 = true rescue LoadError @has_win32 = false end end if @has_win32 bytes = " " * n if @crypt_gen_random.call(@hProv, bytes.size, bytes) == 0 raise SystemCallError, "CryptGenRandom failed: #{lastWin32ErrorMessage}" end return bytes end raise NotImplementedError, "No random device" end
::random_number generates a random number.
If an positive integer is given as n, ::random_number returns an integer: 0 <= ::random_number < n.
If 0 is given or an argument is not given, ::random_number returns an float: 0.0 <= ::random_number < 1.0.
# File lib/compat/securerandom.rb, line 158 def self.random_number(n=0) if 0 < n hex = n.to_s(16) hex = '0' + hex if (hex.length & 1) == 1 bin = [hex].pack("H*") first = bin[0..0] mask = first.respond_to?(:ord) ? first.ord : first.sum(8) mask |= mask >> 1 mask |= mask >> 2 mask |= mask >> 4 begin rnd = SecureRandom.random_bytes(bin.length) first = rnd[0..0] ordinal = first.respond_to?(:ord) ? first.ord : first.sum(8) rnd[0..0] = (ordinal & mask).chr end until rnd < bin rnd.unpack("H*")[0].hex else # assumption: Float::MANT_DIG <= 64 i64 = SecureRandom.random_bytes(8).unpack("Q")[0] Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG) end end