# module Random::Formatter

Format raw random number as `Random` does

### Constants

ALPHANUMERIC

### Public Instance Methods

alphanumeric(n=nil) click to toggle source

SecureRandom.alphanumeric generates a random alphanumeric string.

The argument n specifies the length, in characters, of the alphanumeric string to be generated.

If n is not specified or is nil, 16 is assumed. It may be larger in the future.

The result may contain A-Z, a-z and 0-9.

    require 'securerandom'

    SecureRandom.alphanumeric     #=> "2BuBuLf3WfSKyQbR"
    SecureRandom.alphanumeric(10) #=> "i6K93NdqiH"

If a secure random number generator is not available, `NotImplementedError` is raised.

    # File lib/securerandom.rb, line 309
    def alphanumeric(n=nil)
      n = 16 if n.nil?
      choose(ALPHANUMERIC, n)
    end

base64(n=nil) click to toggle source

SecureRandom.base64 generates a random base64 string.

The argument n specifies the length, in bytes, of the random number to be generated. The length of the result string is about 4/3 of n.

If n is not specified or is nil, 16 is assumed. It may be larger in the future.

The result may contain A-Z, a-z, 0-9, “+”, “/” and “=”.

    require 'securerandom'

    SecureRandom.base64 #=> "/2BuBuLf3+WfSKyQbRcc/A=="
    SecureRandom.base64 #=> "6BbW0pxO0YENxn38HMUbcQ=="

If a secure random number generator is not available, `NotImplementedError` is raised.

See RFC 3548 for the definition of base64.

    # File lib/securerandom.rb, line 180
    def base64(n=nil)
      [random_bytes(n)].pack("m0")
    end

hex(n=nil) click to toggle source

SecureRandom.hex generates a random hexadecimal string.

The argument n specifies the length, in bytes, of the random number to be generated. The length of the resulting hexadecimal string is twice of n.

If n is not specified or is nil, 16 is assumed. It may be larger in the future.

The result may contain 0-9 and a-f.

    require 'securerandom'

    SecureRandom.hex #=> "eb693ec8252cd630102fd0d0fb7c3485"
    SecureRandom.hex #=> "91dc3bfb4de5b11d029d376634589b61"

If a secure random number generator is not available, `NotImplementedError` is raised.

    # File lib/securerandom.rb, line 157
    def hex(n=nil)
      random_bytes(n).unpack("H*")[0]
    end

random_number → float click to toggle source
random_number(max) → number
rand → float
rand(max) → number

Generates formatted random number from raw random bytes. See `Random#rand`.

    static VALUE
    rand_random_number(int argc, VALUE *argv, VALUE obj)
    {
        rb_random_t *rnd = try_get_rnd(obj);
        VALUE v = rand_random(argc, argv, obj, rnd);
        if (NIL_P(v)) v = rand_random(0, 0, obj, rnd);
        else if (!v) invalid_argument(argv[0]);
        return v;
    }

random_bytes(n=nil) click to toggle source

SecureRandom.random_bytes generates a random binary string.

The argument n specifies the length of the result string.

If n is not specified or is nil, 16 is assumed. It may be larger in future.

The result may contain any byte: “x00” - “xff”.

    require 'securerandom'

    SecureRandom.random_bytes #=> "\xD8\\\xE0\xF4\r\xB2\xFC*WM\xFF\x83\x18\xF45\xB6"
    SecureRandom.random_bytes #=> "m\xDC\xFC/\a\x00Uf\xB2\xB2P\xBD\xFF6S\x97"

If a secure random number generator is not available, `NotImplementedError` is raised.

    # File lib/securerandom.rb, line 135
    def random_bytes(n=nil)
      n = n ? n.to_int : 16
      gen_random(n)
    end

random_number → float click to toggle source
random_number(max) → number

Generates formatted random number from raw random bytes. See `Random#rand`.

    static VALUE
    rand_random_number(int argc, VALUE *argv, VALUE obj)
    {
        rb_random_t *rnd = try_get_rnd(obj);
        VALUE v = rand_random(argc, argv, obj, rnd);
        if (NIL_P(v)) v = rand_random(0, 0, obj, rnd);
        else if (!v) invalid_argument(argv[0]);
        return v;
    }

urlsafe_base64(n=nil, padding=false) click to toggle source

SecureRandom.urlsafe_base64 generates a random URL-safe base64 string.

The argument n specifies the length, in bytes, of the random number to be generated. The length of the result string is about 4/3 of n.

If n is not specified or is nil, 16 is assumed. It may be larger in the future.

The boolean argument padding specifies the padding. If it is false or nil, padding is not generated. Otherwise padding is generated. By default, padding is not generated because “=” may be used as a URL delimiter.

The result may contain A-Z, a-z, 0-9, “-” and “_”. “=” is also used if padding is true.

    require 'securerandom'

    SecureRandom.urlsafe_base64 #=> "b4GOKm4pOYU_-BOXcrUGDg"
    SecureRandom.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg"

    SecureRandom.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ=="
    SecureRandom.urlsafe_base64(nil, true) #=> "-M8rLhr7JEpJlqFGUMmOxg=="

If a secure random number generator is not available, `NotImplementedError` is raised.

See RFC 3548 for the definition of URL-safe base64.

    # File lib/securerandom.rb, line 212
    def urlsafe_base64(n=nil, padding=false)
      s = [random_bytes(n)].pack("m0")
      s.tr!("+/", "-_")
      s.delete!("=") unless padding
      s
    end

uuid() click to toggle source

SecureRandom.uuid generates a random v4 UUID (Universally Unique IDentifier).

    require 'securerandom'

    SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
    SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"
    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.

    # File lib/securerandom.rb, line 234
    def uuid
      ary = random_bytes(16).unpack("NnnnnN")
      ary[2] = (ary[2] & 0x0fff) | 0x4000
      ary[3] = (ary[3] & 0x3fff) | 0x8000
      "%08x-%04x-%04x-%04x-%04x%08x" % ary
    end

### Private Instance Methods

choose(source, n) click to toggle source

SecureRandom.choose generates a string that randomly draws from a source array of characters.

The argument source specifies the array of characters from which to generate the string. The argument n specifies the length, in characters, of the string to be generated.

The result may contain whatever characters are in the source array.

    require 'securerandom'

    SecureRandom.choose([*'l'..'r'], 16) #=> "lmrqpoonmmlqlron"
    SecureRandom.choose([*'0'..'9'], 5)  #=> "27309"

If a secure random number generator is not available, `NotImplementedError` is raised.

    # File lib/securerandom.rb, line 262
            def choose(source, n)
      size = source.size
      m = 1
      limit = size
      while limit * size <= 0x100000000
        limit *= size
        m += 1
      end
      result = ''.dup
      while m <= n
        rs = random_number(limit)
        is = rs.digits(size)
        (m-is.length).times { is << 0 }
        result << source.values_at(*is).join('')
        n -= m
      end
      if 0 < n
        rs = random_number(limit)
        is = rs.digits(size)
        if is.length < n
          (n-is.length).times { is << 0 }
        else
          is.pop while n < is.length
        end
        result.concat source.values_at(*is).join('')
      end
      result
    end

gen_random(n) click to toggle source

    # File lib/securerandom.rb, line 241
            def gen_random(n)
      self.bytes(n)
    end