ISO/IEC 18031:2011规定了用于加密目的的随机比特发生器的概念模型，以及该模型的元素。 ISO/IEC 18031:2011 指定非确定性随机位发生器所需的主要元素的特性， 指定确定性随机位发生器所需的主要元素的特性， 建立非确定性和确定性随机位生成器的安全要求。 在需要从随机位串产生随机数序列的情况下，ISO/IEC 18031:2011给出了如何执行该操作的指南。 用于独立验证或确认目的的随机比特发生器的统计测试技术以及此类发生器的详细设计超出了ISO/IEC 18031:2011的范围。

ISO/IEC 18031:2011 specifies a conceptual model for a random bit generator for cryptographic purposes, together with the elements of this model. ISO/IEC 18031:2011

• specifies the characteristics of the main elements required for a non-deterministic random bit generator,
• specifies the characteristics of the main elements required for a deterministic random bit generator,
• establishes the security requirements for both the non-deterministic and the deterministic random bit generator.

Where there is a requirement to produce sequences of random numbers from random bit strings, ISO/IEC 18031:2011 gives guidelines on how this can be performed. 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 18031:2011.