Skip to Content Skip to Search

module Digest::UUID

Public class methods

nil_uuid()

Returns the nil UUID. This is a special form of UUID that is specified to have all 128 bits set to zero.

Source code GitHub 
# File activesupport/lib/active_support/core_ext/digest/uuid.rb, line 58
def self.nil_uuid
  "00000000-0000-0000-0000-000000000000"
end

uuid_from_hash(hash_class, namespace, name)

Generates a v5 non-random UUID (Universally Unique IDentifier).

Using OpenSSL::Digest::MD5 generates version 3 UUIDs; OpenSSL::Digest::SHA1 generates version 5 UUIDs. uuid_from_hash always generates the same UUID for a given name and namespace combination.

See RFC 4122 for details of UUID at: www.ietf.org/rfc/rfc4122.txt

Source code GitHub 
# File activesupport/lib/active_support/core_ext/digest/uuid.rb, line 19
def self.uuid_from_hash(hash_class, namespace, name)
  if hash_class == Digest::MD5 || hash_class == OpenSSL::Digest::MD5
    version = 3
  elsif hash_class == Digest::SHA1 || hash_class == OpenSSL::Digest::SHA1
    version = 5
  else
    raise ArgumentError, "Expected OpenSSL::Digest::SHA1 or OpenSSL::Digest::MD5, got #{hash_class.name}."
  end

  uuid_namespace = pack_uuid_namespace(namespace)

  hash = hash_class.new
  hash.update(uuid_namespace)
  hash.update(name)

  ary = hash.digest.unpack("NnnnnN")
  ary[2] = (ary[2] & 0x0FFF) | (version << 12)
  ary[3] = (ary[3] & 0x3FFF) | 0x8000

  "%08x-%04x-%04x-%04x-%04x%08x" % ary
end

uuid_v3(uuid_namespace, name)

Convenience method for uuid_from_hash using OpenSSL::Digest::MD5.

Source code GitHub 
# File activesupport/lib/active_support/core_ext/digest/uuid.rb, line 42
def self.uuid_v3(uuid_namespace, name)
  uuid_from_hash(OpenSSL::Digest::MD5, uuid_namespace, name)
end

uuid_v4()

Convenience method for SecureRandom.uuid.

Source code GitHub 
# File activesupport/lib/active_support/core_ext/digest/uuid.rb, line 52
def self.uuid_v4
  SecureRandom.uuid
end

uuid_v5(uuid_namespace, name)

Convenience method for uuid_from_hash using OpenSSL::Digest::SHA1.

Source code GitHub 
# File activesupport/lib/active_support/core_ext/digest/uuid.rb, line 47
def self.uuid_v5(uuid_namespace, name)
  uuid_from_hash(OpenSSL::Digest::SHA1, uuid_namespace, name)
end

Definition files