/
secrand.rb
98 lines (91 loc) · 3.13 KB
/
secrand.rb
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# secrand.rb - secure random number generator interface
#
# Copyright (C) 2007 Tanaka Akira <akr@fsij.org>
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
# WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
# EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
# IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
# OF SUCH DAMAGE.
begin
require 'openssl'
rescue LoadError
end
module SecRand
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
@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
def self.hex(n=nil)
random_bytes(n).unpack("H*")[0]
end
def self.base64(n=nil)
[random_bytes(n)].pack("m*").delete("\n")
end
end
class Integer
def ord
self
end
end unless defined? 0.ord
def SecRand(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].ord
mask |= mask >> 1
mask |= mask >> 2
mask |= mask >> 4
begin
rnd = SecRand.random_bytes(bin.length)
rnd[0] = (rnd[0].ord & mask).chr
end until rnd < bin
rnd.unpack("H*")[0].hex
else
# assumption: Float::MANT_DIG <= 64
i64 = SecRand.random_bytes(8).unpack("Q")[0]
Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG)
end
end