XDRBG – A New Lean DRBG (N21a)
The well-established DRBGs specified by SP800-90A are prevalent, primarily due to their compliance with FIPS 140-3 requirements and reliance on long-standing cryptographic primitives. However, recent years have seen the emergence of new cryptographic primitives, such as the Keccak algorithm underlying SHA-3 and the SHAKE and Ascon cipher families, offering the potential for leaner and more efficient DRBGs. The XDRBG specification mandates the use of an extensible output function (XOF) like SHAKE or Ascon XOF, presenting a compact yet high-performing DRBG alternative. This specification comes with a security proof and freely available reference implementation, seamlessly integrating with existing standards and CMVP’s entropy requirements. Discussion will cover the security proof, implementation, and usage aspects of XDRBG, with the possibility of its adoption in future updates of SP800-90A, potentially enabling compliance with FIPS 140-3 requirements using modern algorithms.