While reading NIST SP 800-90A, "Recommendation for Random Number Generation Using Deterministic Random Bit Generators", I noted that no stream cipher was included among the various specified solutions.

I also noted that, at least as far as I could tell from the list of other NIST SP 800 series publications, no stream ciphers seem to be currently approved or recommended by NIST.

On the other hand, a set of stream ciphers (MUGI, SNOW 2.0, Rabbit, Decimv2, K2) appear to be currently standardized in ISO/IEC 18033-4:2011.

So my question is:

  • What could be the reasons for NIST to apparently ignore stream ciphers?
  • Is it due to the past failure of any stream ciphers to pass the NESSIE project validation, or is it simply due to reduced interest in dedicated stream ciphers, as compared to stream cipher constructions based on block ciphers (CTR / OFB mode)?
  • 1
    $\begingroup$ look estream project ecrypt.eu.org/stream $\endgroup$
    – ir01
    Jun 30, 2013 at 12:31
  • $\begingroup$ thanks for estream derived portfolio while i only mentionned stream ciphers standardized by ISO. it is strange for me that no stream cipher appears approved by nist for PRG or for encryption $\endgroup$
    – william_fr
    Jun 30, 2013 at 20:49

1 Answer 1


I don't know, but block-cipher based modes of operation have seen a lot more scrutiny. AES in CTR mode has been vetted much more thoroughly than any of those stream ciphers you mention. Moreover, those stream ciphers do not offer compelling benefits over AES-CTR mode. Therefore, it seems to me it would be entirely reasonable to focus on block-cipher based modes of operation.

  • $\begingroup$ thanks for answer & post update with missed URL links. I think you're right and nist might not consider a major interest for stream ciphers. this is not a minor concern according to nist rôle. $\endgroup$
    – william_fr
    Jul 1, 2013 at 10:03
  • $\begingroup$ Why the Alternating Step Generator is not used more is beyond me, there has been no public cryptanalysis(break) of this generator since it was published in 1987,26 years ago, that is long time to stand up to public scrutiny. It may be un-crackable as long as the key length is large enough, it is an amazingly simple algorithm. $\endgroup$ Jul 8, 2013 at 19:09

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