uuid

# SecureRandom.random_number generates a random number. # # If a positive integer is given as n, # SecureRandom.random_number returns an integer, such that: # +0 <= SecureRandom.random_number(n) < n+. # # p SecureRandom.random_number(100) #=> 15 # p SecureRandom.random_number(100) #=> 88 # # If 0 is given or an argument is not given, # SecureRandom.random_number returns a float, such that: # +0.0 <= SecureRandom.random_number() < 1.0+. # # p SecureRandom.random_number #=> 0.596506046187744 # p SecureRandom.random_number #=> 0.350621695741409 # def random_number(n=0)

if 0 < n
  if defined? OpenSSL::BN
    OpenSSL::BN.rand_range(n).to_i
  else
    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 = random_bytes(bin.length)
      rnd[0] = (rnd[0].ord & mask).chr
    end until rnd < bin
    rnd.unpack("H*")[0].hex
  end
else
  # assumption: Float::MANT_DIG <= 64
  if defined? OpenSSL::BN
    i64 = OpenSSL::BN.rand(64, -1).to_i
  else
    i64 = random_bytes(8).unpack("Q")[0]
  end
  Math.ldexp(i64 >> (64-Float::MANT_DIG), -Float::MANT_DIG)
end

end

# SecureRandom.uuid generates a random v4 UUID (Universally Unique IDentifier). # # p SecureRandom.uuid #=> “2d931510-d99f-494a-8c67-87feb05e1594” # p SecureRandom.uuid #=> “bad85eb9-0713-4da7-8d36-07a8e4b00eab” # p SecureRandom.uuid #=> “62936e70-1815-439b-bf89-8492855a7e6b” # # The version 4 UUID is purely random (except the version). # It doesn’t contain meaningful information such as MAC addresses, timestamps, etc. # # The result contains 122 random bits (15.25 random bytes). # # See RFC 4122 for details of UUID. #