ISO/IEC 20085-1 specifies a methodology for the evaluation of non-deterministic or deterministi random bit generators intended to be used for cryptographic applications. The provisions given in ISO/IEC 20085-1 enables the vendor of an RBG to submit well-defined claims of security to an evaluation authority and shall enable an evaluator or a tester, for instance, a validation authority, to evaluate, test, certify or reject these claims.
ISO/IEC 20085-1 is implementation-agnostic. Hence, ISO/IEC 20085-1 offers no specific guidance on design and implementation decisions for random bit generators. However, design and implementation issues influence the evaluation of an RBG in ISO/IEC 20085-1, for instance, because it requires the use of a stochastic model of the random source and because any such model is supported by technical arguments pertaining to the design of the device at hand.
ISO/IEC 20085-1 on random bit generator is useful for:
Cryptographic applications need random numbers for a wide range of tasks. A strong cryptographic random bit generator that is suitable for general cryptographic applications is expected to provide output bit strings that cannot be distinguished with any potentially practical computational effort and any potentially practical sample sizes from bit strings of the same length drawn uniformly at random. Furthermore, such an RBG is expected to offer enhanced backward secrecy and enhanced forward secrecy.
Random bit generators as evaluated in ISO/IEC 20085-1 aim to output bit strings that appear evenly distributed. Depending on the distribution of random numbers required by the consuming application, however, it is worth noting that additional steps can be necessary (and can well be critical to security) for the consuming application to transform the random bit strings produced by the RBG into random numbers of a distribution suitable to the application requirements.
ISO/IEC 20543