Demos are having trouble working with the applet

[gregorjohannson]

I've successfully managed to install the applet on a JC 3.0.4 card from Idemia (Oberthur), following GP spec 2.2.1. The attestation certificate was used from the README examples.

The proprietary dependencies were swapped as follows:

1. KeyBuidlerX.TYPE_AES_STATIC -> KeyBuilder.TYPE_AES
2. KeyAgreementX.ALG_EC_SVDP_DH_PLAIN_XY -> KeyAgreement.ALG_EC_SVDP_DH_PLAIN

http://u2fdemo.appspot.com can register the authenticator, but testing fails.
https://demo.yubico.com/u2f is not capable of registering at all.

Do you have any ideas for what I might be doing wrong?

[tsenger]

Hi, I think the first swap (KeyBuidlerX.TYPE_AES_STATIC -> KeyBuilder.TYPE_AES) is fine.
But the result in the KeyAgreement is different if you use ALG_EC_SVDP_DH_PLAIN instead of ALG_EC_SVDP_DH_PLAIN_XY.

• ALG_EC_SVDP_DH_PLAIN only returns the x coordinate of the point (32 bytes), while
• ALG_EC_SVDP_DH_PLAIN_XY returns the x and the y coordinate (65 bytes).

see also this article

It is possible to calculate the y coordinate to a given x coordinate. But unfortunately I'm not hat deep in elliptic curves.