| Module | ActiveSupport::SecureRandom |
| In: |
vendor/rails/activesupport/lib/active_support/secure_random.rb
|
This library is an interface for secure random number generator which is suitable for generating session key in HTTP cookies, etc.
It supports following secure random number generators.
Note: This module is based on the SecureRandom library from Ruby 1.9, revision 18786, August 23 2008. It‘s 100% interface-compatible with Ruby 1.9‘s SecureRandom library.
# random hexadecimal string.
p SecureRandom.hex(10) #=> "52750b30ffbc7de3b362"
p SecureRandom.hex(10) #=> "92b15d6c8dc4beb5f559"
p SecureRandom.hex(11) #=> "6aca1b5c58e4863e6b81b8"
p SecureRandom.hex(12) #=> "94b2fff3e7fd9b9c391a2306"
p SecureRandom.hex(13) #=> "39b290146bea6ce975c37cfc23"
...
# random base64 string.
p SecureRandom.base64(10) #=> "EcmTPZwWRAozdA=="
p SecureRandom.base64(10) #=> "9b0nsevdwNuM/w=="
p SecureRandom.base64(10) #=> "KO1nIU+p9DKxGg=="
p SecureRandom.base64(11) #=> "l7XEiFja+8EKEtY="
p SecureRandom.base64(12) #=> "7kJSM/MzBJI+75j8"
p SecureRandom.base64(13) #=> "vKLJ0tXBHqQOuIcSIg=="
...
# random binary string.
p SecureRandom.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
p SecureRandom.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
...
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 vendor/rails/activesupport/lib/active_support/secure_random.rb, line 149
149: def self.base64(n=nil)
150: [random_bytes(n)].pack("m*").delete("\n")
151: 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 vendor/rails/activesupport/lib/active_support/secure_random.rb, line 135
135: def self.hex(n=nil)
136: random_bytes(n).unpack("H*")[0]
137: 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 vendor/rails/activesupport/lib/active_support/secure_random.rb, line 64
64: def self.random_bytes(n=nil)
65: n ||= 16
66:
67: if defined? OpenSSL::Random
68: return OpenSSL::Random.random_bytes(n)
69: end
70:
71: if !defined?(@has_urandom) || @has_urandom
72: flags = File::RDONLY
73: flags |= File::NONBLOCK if defined? File::NONBLOCK
74: flags |= File::NOCTTY if defined? File::NOCTTY
75: flags |= File::NOFOLLOW if defined? File::NOFOLLOW
76: begin
77: File.open("/dev/urandom", flags) {|f|
78: unless f.stat.chardev?
79: raise Errno::ENOENT
80: end
81: @has_urandom = true
82: ret = f.readpartial(n)
83: if ret.length != n
84: raise NotImplementedError, "Unexpected partial read from random device"
85: end
86: return ret
87: }
88: rescue Errno::ENOENT
89: @has_urandom = false
90: end
91: end
92:
93: if !defined?(@has_win32)
94: begin
95: require 'Win32API'
96:
97: crypt_acquire_context = Win32API.new("advapi32", "CryptAcquireContext", 'PPPII', 'L')
98: @crypt_gen_random = Win32API.new("advapi32", "CryptGenRandom", 'LIP', 'L')
99:
100: hProvStr = " " * 4
101: prov_rsa_full = 1
102: crypt_verifycontext = 0xF0000000
103:
104: if crypt_acquire_context.call(hProvStr, nil, nil, prov_rsa_full, crypt_verifycontext) == 0
105: raise SystemCallError, "CryptAcquireContext failed: #{lastWin32ErrorMessage}"
106: end
107: @hProv, = hProvStr.unpack('L')
108:
109: @has_win32 = true
110: rescue LoadError
111: @has_win32 = false
112: end
113: end
114: if @has_win32
115: bytes = " " * n
116: if @crypt_gen_random.call(@hProv, bytes.size, bytes) == 0
117: raise SystemCallError, "CryptGenRandom failed: #{lastWin32ErrorMessage}"
118: end
119: return bytes
120: end
121:
122: raise NotImplementedError, "No random device"
123: 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 vendor/rails/activesupport/lib/active_support/secure_random.rb, line 162
162: def self.random_number(n=0)
163: if 0 < n
164: hex = n.to_s(16)
165: hex = '0' + hex if (hex.length & 1) == 1
166: bin = [hex].pack("H*")
167: mask = bin[0]
168: mask |= mask >> 1
169: mask |= mask >> 2
170: mask |= mask >> 4
171: begin
172: rnd = SecureRandom.random_bytes(bin.length)
173: rnd[0] = rnd[0] & mask
174: end until rnd < bin
175: rnd.unpack("H*")[0].hex
176: else
177: # assumption: Float::MANT_DIG <= 64
178: i64 = SecureRandom.random_bytes(8).unpack("Q")[0]
179: Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG)
180: end
181: end