Correction: Re: RFC8410 (in)compatibility

Anders Rundgren anders.rundgren.net at gmail.com
Sat Aug 29 14:14:44 UTC 2020


The RFC8410 author claims that the public key featured in the "self-issued" certificate is NOT related to the signature key.
The answer to my question is thus (?) that "Signature" should (as BC does) reject X25519 keys.

All is good :-)

Anders

On 2020-08-28 16:07, Anders Rundgren wrote:
> On 2020-08-28 15:58, Weijun Wang wrote:
>> Is “Ed25519” what you need? It’s not available in JDK 11. See https://bugs.openjdk.java.net/browse/JDK-8199231.
> 
> I know, that's why I wrote that I currently use BC (BouncyCastle).
> 
> My question is thus applicable to JDK 15.  BC apparently rejects X25519 signature keys.  Probably for a reason.
> 
> Regards,
> Anders
> 
>>
>> —Max
>>
>>> On Aug 28, 2020, at 9:55 AM, Anders Rundgren <anders.rundgren.net at gmail.com> wrote:
>>>
>>> On 2020-08-28 15:41, Weijun Wang wrote:
>>>> What version of java are you using and what’s your command to generate the key pair?
>>>
>>> Hi Max,
>>>
>>> While waiting for JDK 15, I'm currently using JDK11 and BC but the question is really about the Signature object specification.
>>>
>>>    KeyPairGenerator kpg = KeyPairGenerator.getInstance("X25519")
>>>    KeyPair kp = kpg.generateKeyPair();
>>>
>>> A self-signed X25519 certificate would require that a X25519 key is useful as a signature key.
>>>
>>> Note: I'm not proposing such a feature, I'm just trying to understand :)
>>>
>>> Regards,
>>> Anders
>>>> Thanks,
>>>> Max
>>>>> On Aug 28, 2020, at 7:03 AM, Anders Rundgren <anders.rundgren.net at gmail.com> wrote:
>>>>>
>>>>> Hi Crypto Experts,
>>>>>
>>>>> Please pardon my ignorance regarding curve25519, but I ran into problems [*] trying to recreate the sample certificate:
>>>>> https://urldefense.com/v3/__https://tools.ietf.org/html/rfc8410*section-10.2__;Iw!!GqivPVa7Brio!OMTnVBdbrt8MuV8YwHsti8iuWLk2QE3C6FGAQeBoMJj9pIBQiRO6cbcSLzY8F_90TQ$
>>>>> It seems that the certificate is signed with a key intended for ECDH.
>>>>> Question: is Java's "Signature" object supposed to accept X25519 keys?
>>>>>
>>>>> Personally I don't see any use of a self-signed encryption certificate so maybe this is just a bad example...kind of edge case.
>>>>>
>>>>> Regards,
>>>>> Anders Rundgren
>>>>>
>>>>> *] java.security.InvalidKeyException: cannot identify EdDSA private key
>>>
>>
> 



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