Missing documentation for EdDSA key serialization

Anthony Scarpino anthony.scarpino at oracle.com
Mon Aug 31 18:00:30 UTC 2020

On 8/31/20 8:16 AM, Anders Rundgren wrote:
> On
> https://tools.ietf.org/html/rfc8032#page-24
> you can find test vectors that are also used by rfc8037 (JOSE).
> However, there seems to be no information on how to create an EdDSA 
> public key from such a vector.
> Apparently you must be an expert on the inner workings of EdDSA in order 
> to use this API.
> I have though managed(...) but 1) it looks strange 2) it may be incorrect.
> Steps
> 1. Convert the hex-code to a byte[] array.
> 2. Reverse (!) all the bytes in the byte[] array.
> 3. publicKey = kf.generatePublic(
>                      new EdECPublicKeySpec(new NamedParameterSpec(alg),
>                                            new EdECPoint(false, new 
> BigInteger(1, theByteArray))));
> Ideally, EdECPoint should have an constructor that does whatever it 
> takes based on a byte[] array.
> It is equally fuzzy in the other direction.  A "getByteArray()" on 
> EdECPoint had been great.
> Thanx,
> Anders


It does seem like a constructor and/or helper methods would be a good 
addition.  I filed a bug to track this:




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