ISO/IEC 18031:2005 specifies a conceptual model for a random bit generator for cryptographic purposes, together with the elements of this model. ISO/IEC 18031:2005 also includes the description of the main elements required for a non-deterministic random bit generator;the description of the main elements required for a deterministic random bit generator;their characteristics; their security requirements. Techniques for statistical testing of random bit generators for the purposes of independent verification or validation, and detailed designs for such generators, are outside the scope of ISO/IEC 18031:2005.