module SecureRandom
Public Class Methods
SecureRandom.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 145 def self.base64(n=nil) 146 [random_bytes(n)].pack("m*").delete("\n") 147 end
SecureRandom.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 131 def self.hex(n=nil) 132 random_bytes(n).unpack("H*")[0] 133 end
SecureRandom.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 52 def self.random_bytes(n=nil) 53 n ||= 16 54 55 if defined? OpenSSL::Random 56 return OpenSSL::Random.random_bytes(n) 57 end 58 59 if !defined?(@has_urandom) || @has_urandom 60 flags = File::RDONLY 61 flags |= File::NONBLOCK if defined? File::NONBLOCK 62 flags |= File::NOCTTY if defined? File::NOCTTY 63 flags |= File::NOFOLLOW if defined? File::NOFOLLOW 64 begin 65 File.open("/dev/urandom", flags) {|f| 66 unless f.stat.chardev? 67 raise Errno::ENOENT 68 end 69 @has_urandom = true 70 ret = f.readpartial(n) 71 if ret.length != n 72 raise NotImplementedError, 73 "Unexpected partial read from random device" 74 end 75 return ret 76 } 77 rescue Errno::ENOENT 78 @has_urandom = false 79 end 80 end 81 82 if !defined?(@has_win32) 83 begin 84 require 'Win32API' 85 86 crypt_acquire_context = Win32API.new( 87 "advapi32", "CryptAcquireContext", 'PPPII', 'L' 88 ) 89 @crypt_gen_random = Win32API.new( 90 "advapi32", "CryptGenRandom", 'LIP', 'L' 91 ) 92 93 hProvStr = " " * 4 94 prov_rsa_full = 1 95 crypt_verifycontext = 0xF0000000 96 97 if crypt_acquire_context.call( 98 hProvStr, nil, nil, prov_rsa_full, crypt_verifycontext) == 0 99 raise SystemCallError, 100 "CryptAcquireContext failed: #{lastWin32ErrorMessage}" 101 end 102 @hProv, = hProvStr.unpack('L') 103 104 @has_win32 = true 105 rescue LoadError 106 @has_win32 = false 107 end 108 end 109 if @has_win32 110 bytes = " " * n 111 if @crypt_gen_random.call(@hProv, bytes.size, bytes) == 0 112 raise SystemCallError, 113 "CryptGenRandom failed: #{lastWin32ErrorMessage}" 114 end 115 return bytes 116 end 117 118 raise NotImplementedError, "No random device" 119 end
SecureRandom.random_number generates a random number.
If an positive integer is given as n, SecureRandom.random_number returns an integer: 0 <= SecureRandom.random_number(n) < n.
If 0 is given or an argument is not given, SecureRandom.random_number returns an float: 0.0 <= SecureRandom.random_number() < 1.0.
# File lib/compat/securerandom.rb 158 def self.random_number(n=0) 159 if 0 < n 160 hex = n.to_s(16) 161 hex = '0' + hex if (hex.length & 1) == 1 162 bin = [hex].pack("H*") 163 first = bin[0..0] 164 mask = first.respond_to?(:ord) ? first.ord : first.sum(8) 165 mask |= mask >> 1 166 mask |= mask >> 2 167 mask |= mask >> 4 168 begin 169 rnd = SecureRandom.random_bytes(bin.length) 170 first = rnd[0..0] 171 ordinal = first.respond_to?(:ord) ? first.ord : first.sum(8) 172 rnd[0..0] = (ordinal & mask).chr 173 end until rnd < bin 174 rnd.unpack("H*")[0].hex 175 else 176 # assumption: Float::MANT_DIG <= 64 177 i64 = SecureRandom.random_bytes(8).unpack("Q")[0] 178 Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG) 179 end 180 end