crypto(webcrypto): ECDH Named curve mismatch

[panva]

• Version: v15.0.1
• Platform: Darwin C02CX0K5MD6V 19.6.0 Darwin Kernel Version 19.6.0: Mon Aug 31 22:12:52 PDT 2020; root:xnu-6153.141.2~1/RELEASE_X86_64 x86_64
• Subsystem: crypto.webcrypto

What steps will reproduce the bug?

This rejects

subtle.importKey(
    "jwk",
    {
        kty: "EC",
        crv: "P-256",
        x: "kgR_PqO07L8sZOBbw6rvv7O_f7clqDeiE3WnMkb5EoI",
        y: "djI-XqCqSyO9GFk_QT_stROMCAROIvU8KOORBgQUemE",
        d: "5aPFSt0UFVXYGu-ZKyC9FQIUOAMmnjzdIwkxCMe3Iok",
        alg: 'ECDH-ES',
    },
    {
        name: "ECDH",
        namedCurve: "P-256"
    },
    false,
    ["deriveKey", "deriveBits"]
)

This works, difference is the presence of the JWK "alg" (Algorithm) Parameter

subtle.importKey(
    "jwk",
    {
        kty: "EC",
        crv: "P-256",
        x: "kgR_PqO07L8sZOBbw6rvv7O_f7clqDeiE3WnMkb5EoI",
        y: "djI-XqCqSyO9GFk_QT_stROMCAROIvU8KOORBgQUemE",
        d: "5aPFSt0UFVXYGu-ZKyC9FQIUOAMmnjzdIwkxCMe3Iok",
    },
    {
        name: "ECDH",
        namedCurve: "P-256"
    },
    false,
    ["deriveKey", "deriveBits"]
)

What is the expected behavior?

The key import promise should resolve. (I think, at least it does in Chromium's Web Crypto API implementation.

// cc @jasnell

[mmomtchev]

I am not an expert on this, but I think P-256 curve should be used only with ES256 algorithm
Maybe Chromium ignores crv when you set the algorithm to ECDH-ES
I don't think that P-256 with ECDH-ES is a valid combination, I don't see it in the RFC
https://tools.ietf.org/html/rfc7518

[panva]

@mmomtchev this ticket is not about JOSE per se. But even if it was then of course the three original EC curves are usable for ECDH-ES. secp256k1 isn't per it's jose registration, but that curve isn't supported by webcrypto at all

[panva]

Looking at the spec (webcrypto one) ecdh jwk key import does not work with jwk.alg at all. It seems this is indeed a bug in node's implementation.

[jasnell]

Sounds like it. Do you want to take a look at a fix @panva?

[panva]

@jasnell i'll take a stab at it.