/usr/lib/ruby/1.8/securerandom.rb is in libruby1.8 1.8.7.352-2ubuntu1.6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 | # = 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.
#
# It supports following secure random number generators.
#
# * openssl
# * /dev/urandom
#
# == Example
#
# # 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"
# ...
begin
require 'openssl'
rescue LoadError
end
module SecureRandom
# 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.
def self.random_bytes(n=nil)
n ||= 16
if defined? OpenSSL::Random
@pid = $$ if !defined?(@pid)
pid = $$
if @pid != pid
now = Time.now
ary = [now.to_i, now.usec, @pid, pid]
OpenSSL::Random.seed(ary.to_s)
@pid = pid
end
return OpenSSL::Random.random_bytes(n)
end
if !defined?(@has_urandom) || @has_urandom
@has_urandom = false
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
raise NotImplementedError, "No random device"
end
end
raise NotImplementedError, "No random device"
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.
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 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.
def self.base64(n=nil)
[random_bytes(n)].pack("m*").delete("\n")
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.
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*")
mask = bin[0]
mask |= mask >> 1
mask |= mask >> 2
mask |= mask >> 4
begin
rnd = SecureRandom.random_bytes(bin.length)
rnd[0] = (rnd[0] & 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
end
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