Module: SecureRandom
- Defined in:
- lib/securerandom.rb
Class Method Summary collapse
-
.base64(n = nil) ⇒ Object
SecureRandom.base64 generates a random base64 string.
-
.hex(n = nil) ⇒ Object
SecureRandom.hex generates a random hex string.
-
.random_bytes(n = nil) ⇒ Object
SecureRandom.random_bytes generates a random binary string.
-
.random_number(n = 0) ⇒ Object
SecureRandom.random_number generates a random number.
Class Method Details
.base64(n = nil) ⇒ Object
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.
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# File 'lib/securerandom.rb', line 104 def self.base64(n=nil) [random_bytes(n)].pack("m*").delete("\n") end |
.hex(n = nil) ⇒ Object
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.
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# File 'lib/securerandom.rb', line 90 def self.hex(n=nil) random_bytes(n).unpack("H*")[0] end |
.random_bytes(n = nil) ⇒ Object
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.
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# File 'lib/securerandom.rb', line 50 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 |
.random_number(n = 0) ⇒ Object
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.
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# File 'lib/securerandom.rb', line 117 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 |