summaryrefslogtreecommitdiff
path: root/lib/securerandom.rb
blob: 3e932f6b0ee0fb5540cb5b203e12aaafd6571045 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
# -*- coding: us-ascii -*-
begin
  require 'openssl'
rescue LoadError
end

# == Secure random number generator interface.
#
# This library is an interface for secure random number generator which is
# suitable for generating session key in HTTP cookies, etc.
#
# You can use this library in your application by requiring it:
#
#   require 'securerandom'
#
# It supports following secure random number generators.
#
# * openssl
# * /dev/urandom
# * Win32
#
# === Examples
#
# Hexadecimal string.
#
#   require 'securerandom'
#
#   p SecureRandom.hex(10) #=> "52750b30ffbc7de3b362"
#   p SecureRandom.hex(10) #=> "92b15d6c8dc4beb5f559"
#   p SecureRandom.hex(13) #=> "39b290146bea6ce975c37cfc23"
#
# Base64 string.
#
#   p SecureRandom.base64(10) #=> "EcmTPZwWRAozdA=="
#   p SecureRandom.base64(10) #=> "KO1nIU+p9DKxGg=="
#   p SecureRandom.base64(12) #=> "7kJSM/MzBJI+75j8"
#
# Binary string.
#
#   p SecureRandom.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
#   p SecureRandom.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
module SecureRandom
  if /mswin|mingw/ =~ RUBY_PLATFORM
    require "fiddle/import"

    module AdvApi32 # :nodoc:
      extend Fiddle::Importer
      dlload "advapi32"
      extern "int CryptAcquireContext(void*, void*, void*, unsigned long, unsigned long)"
      extern "int CryptGenRandom(void*, unsigned long, void*)"

      def self.get_provider
        hProvStr = " " * Fiddle::SIZEOF_VOIDP
        prov_rsa_full = 1
        crypt_verifycontext = 0xF0000000

        if CryptAcquireContext(hProvStr, nil, nil, prov_rsa_full, crypt_verifycontext) == 0
          raise SystemCallError, "CryptAcquireContext failed: #{lastWin32ErrorMessage}"
        end
        type = Fiddle::SIZEOF_VOIDP == Fiddle::SIZEOF_LONG_LONG ? 'q' : 'l'
        hProv, = hProvStr.unpack(type)
        hProv
      end

      def self.gen_random(n)
        @hProv ||= get_provider
        bytes = " ".force_encoding("ASCII-8BIT") * n
        if CryptGenRandom(@hProv, bytes.size, bytes) == 0
          raise SystemCallError, "CryptGenRandom failed: #{Kernel32.last_error_message}"
        end
        bytes
      end
    end

    module Kernel32 # :nodoc:
      extend Fiddle::Importer
      dlload "kernel32"
      extern "unsigned long GetLastError()"
      extern "unsigned long FormatMessageA(unsigned long, void*, unsigned long, unsigned long, void*, unsigned long, void*)"

      # Following code is based on David Garamond's GUID library for Ruby.
      def self.last_error_message
        format_message_ignore_inserts = 0x00000200
        format_message_from_system    = 0x00001000

        code = GetLastError()
        msg = "\0" * 1024
        len = FormatMessageA(format_message_ignore_inserts + format_message_from_system, 0, code, 0, msg, 1024, nil)
        msg[0, len].force_encoding("filesystem").tr("\r", '').chomp
      end
    end
  end

  # 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".
  #
  #   p SecureRandom.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6"
  #   p SecureRandom.random_bytes #=> "m\xDC\xFC/\a\x00Uf\xB2\xB2P\xBD\xFF6S\x97"
  #
  # If secure random number generator is not available,
  # NotImplementedError is raised.
  def self.random_bytes(n=nil)
    n = n ? n.to_int : 16
    gen_random(n)
  end

  if defined? OpenSSL::Random
    def self.gen_random(n)
      @pid = 0 unless defined?(@pid)
      pid = $$
      unless @pid == pid
        now = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
        ary = [now, @pid, pid]
        OpenSSL::Random.random_add(ary.join("").to_s, 0.0)
        @pid = pid
      end
      return OpenSSL::Random.random_bytes(n)
    end
  elsif defined?(AdvApi32)
    def self.gen_random(n)
      return AdvApi32.gen_random(n)
    end

    def self.lastWin32ErrorMessage # :nodoc:
      # for compatibility
      return Kernel32.last_error_message
    end
  else
    def self.gen_random(n)
      flags = File::RDONLY
      flags |= File::NONBLOCK if defined? File::NONBLOCK
      flags |= File::NOCTTY if defined? File::NOCTTY
      begin
        File.open("/dev/urandom", flags) {|f|
          unless f.stat.chardev?
            break
          end
          ret = f.read(n)
          unless ret.length == n
            raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
          end
          return ret
        }
      rescue Errno::ENOENT
      end

      raise NotImplementedError, "No random device"
    end
  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 _n_.
  #
  # If _n_ is not specified or is nil, 16 is assumed.
  # It may be larger in future.
  #
  # The result may contain 0-9 and a-f.
  #
  #   p SecureRandom.hex #=> "eb693ec8252cd630102fd0d0fb7c3485"
  #   p SecureRandom.hex #=> "91dc3bfb4de5b11d029d376634589b61"
  #
  # If secure random number generator is not available,
  # NotImplementedError is raised.
  def self.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 future.
  #
  # The result may contain A-Z, a-z, 0-9, "+", "/" and "=".
  #
  #   p SecureRandom.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A=="
  #   p SecureRandom.base64 #=> "6BbW0pxO0YENxn38HMUbcQ=="
  #
  # If secure random number generator is not available,
  # NotImplementedError is raised.
  #
  # See RFC 3548 for the definition of base64.
  def self.base64(n=nil)
    [random_bytes(n)].pack("m*").delete("\n")
  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 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.
  #
  #   p SecureRandom.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg"
  #   p SecureRandom.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg"
  #
  #   p SecureRandom.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ=="
  #   p SecureRandom.urlsafe_base64(nil, true) #=> "-M8rLhr7JEpJlqFGUMmOxg=="
  #
  # If secure random number generator is not available,
  # NotImplementedError is raised.
  #
  # See RFC 3548 for the definition of URL-safe base64.
  def self.urlsafe_base64(n=nil, padding=false)
    s = [random_bytes(n)].pack("m*")
    s.delete!("\n")
    s.tr!("+/", "-_")
    s.delete!("=") unless padding
    s
  end

  # SecureRandom.random_number generates a random number.
  #
  # If a positive integer is given as _n_,
  # SecureRandom.random_number returns an integer:
  # 0 <= SecureRandom.random_number(n) < n.
  #
  #   p SecureRandom.random_number(100) #=> 15
  #   p SecureRandom.random_number(100) #=> 88
  #
  # If 0 is given or an argument is not given,
  # SecureRandom.random_number returns a float:
  # 0.0 <= SecureRandom.random_number() < 1.0.
  #
  #   p SecureRandom.random_number #=> 0.596506046187744
  #   p SecureRandom.random_number #=> 0.350621695741409
  #
  def self.random_number(n=0)
    if 0 < n
      if defined? OpenSSL::BN
        OpenSSL::BN.rand_range(n).to_i
      else
        hex = n.to_s(16)
        hex = '0' + hex if (hex.length & 1) == 1
        bin = [hex].pack("H*")
        mask = bin[0].ord
        mask |= mask >> 1
        mask |= mask >> 2
        mask |= mask >> 4
        begin
          rnd = SecureRandom.random_bytes(bin.length)
          rnd[0] = (rnd[0].ord & mask).chr
        end until rnd < bin
        rnd.unpack("H*")[0].hex
      end
    else
      # assumption: Float::MANT_DIG <= 64
      if defined? OpenSSL::BN
        i64 = OpenSSL::BN.rand(64, -1).to_i
      else
        i64 = SecureRandom.random_bytes(8).unpack("Q")[0]
      end
      Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG)
    end
  end

  # SecureRandom.uuid generates a v4 random UUID (Universally Unique IDentifier).
  #
  #   p SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
  #   p SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
  #   p 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 address, time, etc.
  #
  # See RFC 4122 for details of UUID.
  #
  def self.uuid
    ary = self.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
end