Apple ID Sign In: GetClaims

AppleAuth.java

import io.jsonwebtoken.Claims;
import io.jsonwebtoken.JwsHeader;
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;

import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPublicKeySpec;
import java.util.Base64;

private Claims getClaims(String keyIdentifier, String idToken) throws InvalidKeySpecException, NoSuchAlgorithmException{
  var publicKey = createPublicKeyApple(keyIdentifier);
  try {
    return Jwts.parser().setSigningKey(publicKey).parseClaimsJws(idToken).getBody();
  } catch(Exception e) {
    LOG.info("Exception JWT Signature" + e.getMessage());
    throw new AppleKeysException("Not a right public key");
  }
}