The ML-KEM key does not need to be serialized anywhere so I think its encoding does not matter. If you already have the expanded key you can directly create a NamedPKCS8Key whose expander is an identity function, i.e. both its encoding and expanded key are the expanded key itself. The encoding does not necessarily be the seed.
Thanks, Weijun > On Aug 2, 2025, at 13:42, Sebastian Stenzel <sebastian.sten...@gmail.com> > wrote: > > Hi, > > I merged your NamedPKCS8Key branch into the X-Wing branch and tried to adjust > to the new API. I encountered one problem: > > With your changes, `NamedKEM#implDecapsulate` will now receive the expanded > key (no longer the raw seed). So far, so good. However, in X-Wing I need to > split this into an ML-KEM key and the X25519 key. Now here is the problem: If > I only have expanded bytes, how can I construct an ML-KEM key? NamedPKCS8Key > requires „raw key bytes, not null“ (i.e. the seed) and only optionally the > expanded bytes. > > Is there any internal API I can use to run ML-KEM’s decapsulate with a byte[] > key? > > Otherwise, I would suggest that you widen the signature of > `NamedKEM#implDecapsulate` to receive both parameters, the seed and the > expanded key. > > Cheers, > Sebastian > >> On 23. Jul 2025, at 17:52, Wei-Jun Wang <weijun.w...@oracle.com> wrote: >> >> >> >>> On Jul 23, 2025, at 11:41, Sebastian Stenzel <sebastian.sten...@gmail.com> >>> wrote: >>> >>> Welcome back, I hope you enjoyed the time! :-) >>> >>> If you find time, can you give me an update on the ASN.1 key encoding >>> topic? This is the only remaining issue to fulfill the spec. Afterwards we >>> simply need to wait for the final test vectors and publication of the RFC. >> >> https://github.com/openjdk/jdk/pull/24969 updated NamedPKCS8Key which >> contains both the encoding format (as in PKCS #8) and the expanded format >> (used in calculation). For X-Wing, I think the encoding will be the seed, >> but you are free to choose the expanded format, or, you can "expand" it to >> an arbitrary object at NamdKEM::implCheckPrivateKey. The KeyPairGenerator >> interface does not have a deterministic generateKey method so you will have >> to call internal methods for both ML-KEM and x25519. >> >> Thanks, >> Weijun >> >>> >>> Thank you! >>> Sebastian >>> >>>> Am 23.07.2025 um 14:33 schrieb Wei-Jun Wang <weijun.w...@oracle.com>: >>>> >>>> Hi Sebastian, >>>> >>>> I'm back from my vacation. Thanks for the update. >>>> >>>> I agree, using NamedKey is probably a better choice anyway. It's nice that >>>> getParams() always return a name and we don't need to call getAlgorithm() >>>> as a fallback. >>>> >>>> Thanks, >>>> Weijun >>>> >>>>> On Jun 30, 2025, at 06:06, Sebastian Stenzel >>>>> <sebastian.sten...@gmail.com> wrote: >>>>> >>>>> Quoting Bas Westerbaan (in CC) again, we will most likely see further >>>>> PQ/T hybrids from the IETF crypto forum research group (CFRG for short): >>>>> >>>>>> It seems likely that the CFRG will at some point produce a >>>>>> P-384+ML-KEM-1024 hybrid. See >>>>>> https://mailarchive.ietf.org/arch/msg/cfrg/CwrVvm-J7o85TEWkG9RJxZwfXDY/ >>>>>> . That might take some time. >>>>>> >>>>>> Very few (but notably Ericsson) have asked for X448 hybrids, so I don't >>>>>> expect them soon. >>>>> >>>>> That said, the construction does not necessarily be compatible to X-Wing. >>>>> Just to be sure, I asked whether they see any value in parameterizing >>>>> X-Wing to swap out algorithms. This is what Bas replied: >>>>> >>>>>> Even if the other hybrids will also use an X-Wing style combiner, it >>>>>> doesn't hurt not to parametrize initially. :) >>>>> >>>>> So I would suggest to follow this advice for now and only refactor the >>>>> implementation eventually, when further pairs of algorithms are combined >>>>> in the same way. >>>>> >>>>> Best, >>>>> Sebastian >>>>> >>>>> >>>>>>> On 29. Jun 2025, at 12:02, Sebastian Stenzel >>>>>>> <sebastian.sten...@gmail.com> wrote: >>>>>> >>>>>> >>>>>>> On 28. Jun 2025, at 00:12, Wei-Jun Wang <weijun.w...@oracle.com> wrote: >>>>>>> >>>>>>> [...] After all, there is no parameter for X-Wing. Did you hear the >>>>>>> authors they want to introduce other algorithms like ed448 and >>>>>>> ML-KEM-1024 into it? >>>>>> >>>>>> I forwarded this question and let you know the answer! >>>>>> >>>>>> >>>>>>>> >>>>>>>>> On 7. Jun 2025, at 23:34, Wei-Jun Wang <weijun.w...@oracle.com> wrote: >>>>>>>>> >>>>>>>>> Cool. >>>>>>>>> >>>>>>>>> The current NamedPKCS8Key was designed based on an older approach >>>>>>>>> where modern asymmetric keys store private key data in a nested OCTET >>>>>>>>> STRING format. This pattern was introduced with EdDSA and XDH, and at >>>>>>>>> the time of JDK 24, we anticipated it would become the norm. >>>>>>>>> >>>>>>>>> However, things have changed significantly, as seen in the evolution >>>>>>>>> of draft-ietf-lamps-dilithium-certificates and >>>>>>>>> draft-ietf-lamps-kyber-certificates. The original design now needs to >>>>>>>>> be revised. While we’re still waiting for the IETF drafts to be >>>>>>>>> finalized, we’re already experimenting with changes in >>>>>>>>> https://github.com/openjdk/jdk/pull/24969. >>>>>>>>> >>>>>>>>> Hopefully, by the time X-Wing is finalized, we’ll already have a >>>>>>>>> solution in place. >>>>>>>>> >>>>>>>>> Thanks, >>>>>>>>> Weijun >>>>>>>>> >>>>>>>>>> On Jun 7, 2025, at 16:14, Sebastian Stenzel >>>>>>>>>> <sebastian.sten...@gmail.com> wrote: >>>>>>>>>> >>>>>>>>>> Hi Weijun, >>>>>>>>>> >>>>>>>>>> I got a mostly working implementation based on NamedKEM [0], however >>>>>>>>>> to fulfil the spec I need your advice: >>>>>>>>>> >>>>>>>>>> The (current) X-Wing spec wants this PKCS#8 encoding: [1] >>>>>>>>>> >>>>>>>>>> However, the NamedPKCS8Key implementation always puts a nested >>>>>>>>>> OctetString into the private key part. [2] >>>>>>>>>> >>>>>>>>>> Note the difference here: >>>>>>>>>> * >>>>>>>>>> https://lapo.it/asn1js/#MDQCAQAwDQYLKwYBBAGD5i2ByHoEIAABAgMEBQYHCAkKCwwNDg8QERITFBUWFxgZGhscHR4f >>>>>>>>>> * >>>>>>>>>> https://lapo.it/asn1js/#MDYCAQAwDQYLKwYBBAGD5i2ByHoEIgQg9IFQEyQtdLJL8j-hRm6Yzx3CzFiDyNk4yCADl6ZiXWo >>>>>>>>>> >>>>>>>>>> I believe we need some more flexibility, as the ASN.1 standard >>>>>>>>>> leaves it open to the algorithms how a private key is formatted. >>>>>>>>>> What do you think how to approach this? >>>>>>>>>> >>>>>>>>>> Or should I ask the authors whether they have a specific encoding in >>>>>>>>>> mind? The ASN.1 definitions in the spec don’t seem to be complete >>>>>>>>>> yet. >>>>>>>>>> >>>>>>>>>> Best regards, >>>>>>>>>> Sebastian >>>>>>>>>> >>>>>>>>>> [0]: >>>>>>>>>> https://github.com/openjdk/jdk/compare/master...overheadhunter:jdk:x-wing >>>>>>>>>> [1]: >>>>>>>>>> https://www.ietf.org/archive/id/draft-connolly-cfrg-xwing-kem-07.html#appendix-D >>>>>>>>>> [2]: >>>>>>>>>> https://github.com/openjdk/jdk/blob/d7352559195b9e052c3eb24d773c0d6c10dc23ad/src/java.base/share/classes/sun/security/pkcs/NamedPKCS8Key.java#L76-L81 >>>>>>>>>> >>>>>>>>>>> On 30. May 2025, at 15:03, Wei-Jun Wang <weijun.w...@oracle.com> >>>>>>>>>>> wrote: >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>>> On May 30, 2025, at 08:40, Sebastian Stenzel >>>>>>>>>>>> <sebastian.sten...@gmail.com> wrote: >>>>>>>>>>>> >>>>>>>>>>>> Hi Weijun, >>>>>>>>>>>> >>>>>>>>>>>> waiting for the final standard is understandable. The internals >>>>>>>>>>>> may still change, but the „outer hull“ of the PR is something that >>>>>>>>>>>> could already be discussed before - under these premises, would it >>>>>>>>>>>> make sense to already start a draft? Knowing that it won’t be >>>>>>>>>>>> merged yet? >>>>>>>>>>> >>>>>>>>>>> Feel free to start a draft if you’d like. I'll create a JBS issue >>>>>>>>>>> once we decide we want to include it in the JDK. >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> I have a working set of KeyPairGenerator, KeyFactory and KEM SPI >>>>>>>>>>>> including test vectors basically ready - just SHAKE256 currently >>>>>>>>>>>> borrowed from BC. >>>>>>>>>>>> >>>>>>>>>>>> I know that using SHAKE256 within the JDK is not a problem. >>>>>>>>>>>> However if we want to make it public, there simply *is no* XOF API >>>>>>>>>>>> in JCA. Technically the expand step of the KDF API can be used, >>>>>>>>>>>> but semantically that would be a misuse. Adding a completely new >>>>>>>>>>>> API is nothing I currently want to work on. >>>>>>>>>>> >>>>>>>>>>> I see. >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Btw I am somewhat familiar with the development process as I have >>>>>>>>>>>> started contributing to the JDK in 2021 on cipher and NIO issues. >>>>>>>>>>>> [1] >>>>>>>>>>> >>>>>>>>>>> Nice to know. Sorry I didn't noticed that earlier. >>>>>>>>>>> >>>>>>>>>>> Thanks, >>>>>>>>>>> Weijun >>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> Thank you, >>>>>>>>>>>> Sebastian >>>>>>>>>>>> >>>>>>>>>>>> [1] >>>>>>>>>>>> https://github.com/openjdk/jdk/pulls?q=is%3Apr+author%3Aoverheadhunter >>>>>>>>>>>> >>>>>>>>>>>>> On 29. May 2025, at 18:44, Wei-Jun Wang <weijun.w...@oracle.com> >>>>>>>>>>>>> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>> Hi Sebastian. >>>>>>>>>>>>> >>>>>>>>>>>>>> On May 24, 2025, at 05:40, Sebastian Stenzel >>>>>>>>>>>>>> <sebastian.sten...@gmail.com> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>> Hi all, >>>>>>>>>>>>>> >>>>>>>>>>>>>> For the past few months I have been in contact with one of the >>>>>>>>>>>>>> authors of two spec drafts for future JOSE encryption standards >>>>>>>>>>>>>> [1] [2] with the latter of them relying on X-Wing. >>>>>>>>>>>>>> >>>>>>>>>>>>>> As the X-Wing spec doesn’t face significant changes any more >>>>>>>>>>>>>> (there have been some larger shifts in regards to secret key >>>>>>>>>>>>>> derivation last year), I am now tasked to create a prototype >>>>>>>>>>>>>> implementation for these RFCs. >>>>>>>>>>>>> >>>>>>>>>>>>> Thanks for your continued interest on enhancing OpenJDK. >>>>>>>>>>>>> >>>>>>>>>>>>> That said, we have a policy of not implementing algorithms that >>>>>>>>>>>>> haven't been standardized. So we won't be able to consider your >>>>>>>>>>>>> contribution until IETF publishes draft-connolly-cfrg-xwing-kem >>>>>>>>>>>>> as an RFC. I'm not sure how familiar you are with the OpenJDK >>>>>>>>>>>>> developing process, but in the meantime, you might find it >>>>>>>>>>>>> helpful to read the OpenJDK Developers’ Guide [1] and try working >>>>>>>>>>>>> on something smaller first. >>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> All the primitives for X-Wing are technically already there in >>>>>>>>>>>>>> OpenJDK, however two of them are private API (namely SHAKE256 >>>>>>>>>>>>>> and ML-KEM’s `KeyGen_internal(d, z)` [3]). So the question >>>>>>>>>>>>>> arises whether I can contribute an X-Wing KEM implementation to >>>>>>>>>>>>>> the JDK at the current state of the spec? >>>>>>>>>>>>> >>>>>>>>>>>>> It's acceptable to use private API inside OpenJDK when you are >>>>>>>>>>>>> working on OpenJDK itself. After all, we created them for this >>>>>>>>>>>>> very purpose. However, please keep in mind that this means you >>>>>>>>>>>>> bind your X-Wing implementation to the SunJCE/SunEC >>>>>>>>>>>>> implementations. Usually, as a higher-level algorithm, if its >>>>>>>>>>>>> underlying algorithms could be implemented by different security >>>>>>>>>>>>> providers, it will be nice to make it provider-neutral where >>>>>>>>>>>>> possible. >>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> Alternatively, can we make the two mentioned APIs public? >>>>>>>>>>>>> >>>>>>>>>>>>> No. These methods are too specific to their respective >>>>>>>>>>>>> algorithms. We prefer JCA/JCE-style API that is algorithm-neutral. >>>>>>>>>>>>> >>>>>>>>>>>>> [1] https://openjdk.org/guide/ >>>>>>>>>>>>> >>>>>>>>>>>>> Thanks, >>>>>>>>>>>>> Weijun >>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> Cheers! >>>>>>>>>>>>>> Sebastian >>>>>>>>>>>>>> >>>>>>>>>>>>>> [1]: >>>>>>>>>>>>>> https://datatracker.ietf.org/doc/html/draft-ietf-jose-hpke-encrypt/ >>>>>>>>>>>>>> [2]: >>>>>>>>>>>>>> https://datatracker.ietf.org/doc/html/draft-reddy-cose-jose-pqc-hybrid-hpke-07 >>>>>>>>>>>>>> [3]: >>>>>>>>>>>>>> https://github.com/openjdk/jdk/blob/070c84cd22485a93a562a7639439fb056e840861/src/java.base/share/classes/com/sun/crypto/provider/ML_KEM.java#L498-L536 >>>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>> >>>>>> >>>>> >>>> >> >
