feat: Add ES256 support to JWK

[bshaffer]

See #339

Adds support for parsing EC256 JWKs

You can test this branch by running the following command:

composer require firebase/php-jwt:dev-add-ec-jwk-support

Then in your code, use as you normally would:

$jwk = ["keys": [["kty" => "EC","use" => "sig","crv" => "P-256", "kid" => "jwk1", "x": => "abc..", "y" => "xyz..", "alg" => "ES256"]]];
$keys = JWK::parseKeySet($jwk);
$decoded = JWT::decode($ecJwt, $keys);

[glen-84]

Could this be backported to 6.0.x?

[bshaffer]

@glen-84 What is your use-case? You'd like to see this supported in a version <= PHP 7.1?

[dunglas]

I tested this branch while implement Solid Client PHP and it worked as expected.

See also jumbojett/OpenID-Connect-PHP#287.

[glen-84]

@bshaffer,

@glen-84 What is your use-case? You'd like to see this supported in a version <= PHP 7.1?

Ya, we're currently stuck on PHP 7.0 for a while.

Edit: We're on 7.4 now, FWIW.

[ivaxer]

@bshaffer Could you tell me please why this PR is not merged? Can I help?