зеркало из https://github.com/github/ruby.git
129 строки
3.7 KiB
Ruby
129 строки
3.7 KiB
Ruby
# = Secure random number generator interface.
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#
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# This library is a interface for secure random number generator which is
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# suitable for HTTP cookies, nonces, etc.
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#
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# It supports following secure random number generators.
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#
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# * openssl
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# * /dev/urandom
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#
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# == Example
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#
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# # random hexadecimal string.
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# p SecRand.hex(10) #=> "52750b30ffbc7de3b362"
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# p SecRand.hex(10) #=> "92b15d6c8dc4beb5f559"
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# p SecRand.hex(11) #=> "6aca1b5c58e4863e6b81b8"
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# p SecRand.hex(12) #=> "94b2fff3e7fd9b9c391a2306"
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# p SecRand.hex(13) #=> "39b290146bea6ce975c37cfc23"
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# ...
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#
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# # random base64 string.
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# p SecRand.base64(10) #=> "EcmTPZwWRAozdA=="
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# p SecRand.base64(10) #=> "9b0nsevdwNuM/w=="
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# p SecRand.base64(10) #=> "KO1nIU+p9DKxGg=="
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# p SecRand.base64(11) #=> "l7XEiFja+8EKEtY="
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# p SecRand.base64(12) #=> "7kJSM/MzBJI+75j8"
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# p SecRand.base64(13) #=> "vKLJ0tXBHqQOuIcSIg=="
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# ...
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#
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# # random binary string.
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# p SecRand.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
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# p SecRand.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"
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# ...
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begin
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require 'openssl'
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rescue LoadError
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end
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module SecRand
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# SecRand.random_bytes generates a random binary string.
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#
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# The argument n specifies the length of the result string.
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#
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# If secure random number generator is not available,
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# NotImplementedError is raised.
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def self.random_bytes(n=nil)
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n ||= 16
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if defined? OpenSSL::Random
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return OpenSSL::Random.random_bytes(n)
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end
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if !defined?(@has_urandom) || @has_urandom
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@has_urandom = false
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flags = File::RDONLY
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flags |= File::NONBLOCK if defined? File::NONBLOCK
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flags |= File::NOCTTY if defined? File::NOCTTY
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flags |= File::NOFOLLOW if defined? File::NOFOLLOW
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begin
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File.open("/dev/urandom", flags) {|f|
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unless f.stat.chardev?
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raise Errno::ENOENT
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end
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@has_urandom = true
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ret = f.readpartial(n)
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if ret.length != n
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raise NotImplementedError, "Unexpected partial read from random device"
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end
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return ret
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}
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rescue Errno::ENOENT
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raise NotImplementedError, "No random device"
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end
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end
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raise NotImplementedError, "No random device"
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end
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# SecRand.hex generates a random hex string.
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#
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# The argument n specifies the length of the random length.
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# The length of the result string is twice of n.
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#
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# If secure random number generator is not available,
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# NotImplementedError is raised.
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def self.hex(n=nil)
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random_bytes(n).unpack("H*")[0]
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end
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# SecRand.base64 generates a random base64 string.
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#
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# The argument n specifies the length of the random length.
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# The length of the result string is about 4/3 of n.
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#
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# If secure random number generator is not available,
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# NotImplementedError is raised.
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def self.base64(n=nil)
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[random_bytes(n)].pack("m*").delete("\n")
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end
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# SecRand.random_number generates a random number.
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#
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# If an positive integer is given as n,
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# SecRand.random_number returns an integer:
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# 0 <= SecRand.random_number(n) < n.
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#
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# If 0 is given or an argument is not given,
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# SecRand.random_number returns an float:
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# 0.0 <= SecRand.random_number() < 1.0.
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def self.random_number(n=0)
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if 0 < n
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hex = n.to_s(16)
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hex = '0' + hex if (hex.length & 1) == 1
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bin = [hex].pack("H*")
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mask = bin[0].ord
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mask |= mask >> 1
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mask |= mask >> 2
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mask |= mask >> 4
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begin
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rnd = SecRand.random_bytes(bin.length)
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rnd[0] = (rnd[0].ord & mask).chr
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end until rnd < bin
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rnd.unpack("H*")[0].hex
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else
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# assumption: Float::MANT_DIG <= 64
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i64 = SecRand.random_bytes(8).unpack("Q")[0]
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Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG)
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end
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end
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end
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