Récupérer le certificat public au format PEM à partir d'un JWKS

GetKey.java

///usr/bin/env jbang "$0" "$@" ; exit $?
//DEPS info.picocli:picocli:4.5.0
//DEPS org.bitbucket.b_c:jose4j:0.7.6

import picocli.CommandLine;
import picocli.CommandLine.Command;
import picocli.CommandLine.Parameters;

import java.util.List;
import java.util.concurrent.Callable;

import org.jose4j.jwk.HttpsJwks;
import org.jose4j.jwk.JsonWebKey;
import org.jose4j.keys.RsaKeyUtil;

@Command(name = "GetKey", mixinStandardHelpOptions = true, version = "GetKey 0.1",
        description = "GetKey made with jbang")
class GetKey implements Callable<Integer> {

    @Parameters(index = "0", description = "URL vers JSON Web Key Sets (JWKS)")
    private String url;

    public static void main(String... args) {
        int exitCode = new CommandLine(new GetKey()).execute(args);
        System.exit(exitCode);
    }

    @Override
    public Integer call() throws Exception { 
        HttpsJwks jwks = new HttpsJwks(url);
		List<JsonWebKey> liste = jwks.getJsonWebKeys();
		for (JsonWebKey jsonWebKey : liste) {
			String cert = RsaKeyUtil.pemEncode(jsonWebKey.getPublicKey());
			System.out.println(cert);
		}
        return 0;
    }
}