Random::Formatter

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 securerandom.rb, line 306
def alphanumeric(n=nil)
  n = 16 if n.nil?
  choose(ALPHANUMERIC, n)
end
            

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 securerandom.rb, line 177
def base64(n=nil)
  [random_bytes(n)].pack("m0")
end
            

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 securerandom.rb, line 154
def hex(n=nil)
  random_bytes(n).unpack("H*")[0]
end
            

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 securerandom.rb, line 132
def random_bytes(n=nil)
  n = n ? n.to_int : 16
  gen_random(n)
end
            

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 securerandom.rb, line 209
def urlsafe_base64(n=nil, padding=false)
  s = [random_bytes(n)].pack("m0")
  s.tr!("+/", "-_")
  s.delete!("=") unless padding
  s
end
            

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 securerandom.rb, line 231
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