Amazon Cognito の署名検証のコードを書いたので一旦メモとして残す。
import java.math.BigInteger import java.net.URI import java.security.interfaces.RSAPublicKey import java.security.spec.RSAPublicKeySpec import java.security.{KeyFactory, PublicKey} import java.util.Base64 import com.auth0.jwt.JWT import com.auth0.jwt.algorithms.Algorithm import spray.json._ private case class Key(alg: String, e: String, kid: String, kty: String, n: String, use: String) private case class JwksJson(keys: Array[Key]) private object JwksJsonProtocol extends DefaultJsonProtocol { implicit val keyJsonFormat = jsonFormat6(Key) implicit val inputJsonFormat = jsonFormat(JwksJson, "keys") } trait OpenIDConnectGetKey { val openIdConnectUrl: String private lazy val jwksJsonUrl = new URI(openIdConnectUrl.concat("/.well-known/jwks.json")) private var keys: Map[String, PublicKey] = Map.empty def openIDConnectGetKeys: Map[String, PublicKey] = { import JwksJsonProtocol._ val input = jwksJsonUrl.toURL.openStream() try { val bytes = Stream.continually(input.read).takeWhile(_ != -1).map(_.toByte).toArray val jwksJson = JsonParser(bytes).convertTo[JwksJson] keys ++= jwksJson.keys.map { key => val kty = key.kty val modulus = new BigInteger(1, Base64.getUrlDecoder.decode(key.n)) val publicExponent = new BigInteger(1, Base64.getUrlDecoder.decode(key.e)) val keySpec = new RSAPublicKeySpec(modulus, publicExponent) key.kid -> KeyFactory.getInstance(kty).generatePublic(keySpec) }.toMap keys } finally { input.close() } } def verify(idToken: String): JsValue = { val jwt = JWT.decode(idToken) val maybePublicKey = keys.get(jwt.getKeyId) match { case None => openIDConnectGetKeys.get(jwt.getKeyId) case s => s } maybePublicKey map { publicKey => val algorithm = Algorithm.RSA256(publicKey.asInstanceOf[RSAPublicKey], null) val verification = JWT.require(algorithm) verification.build().verify(jwt) } getOrElse(throw new RuntimeException(s"Not exists ${jwt.getKeyId}")) JsonParser(Base64.getUrlDecoder().decode(jwt.getPayload)) } }
Java で書いてみた
import com.auth0.jwt.JWT; import com.auth0.jwt.algorithms.Algorithm; import com.auth0.jwt.interfaces.DecodedJWT; import com.auth0.jwt.interfaces.Verification; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.ObjectMapper; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.math.BigInteger; import java.net.URI; import java.net.URISyntaxException; import java.security.KeyFactory; import java.security.NoSuchAlgorithmException; import java.security.interfaces.RSAPublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.KeySpec; import java.security.spec.RSAPublicKeySpec; import java.util.Base64; import java.util.HashMap; import java.util.Map; public interface OpenIDConnectGetKeys { Map<String, KeyItem> getKeys(); void saveKeys(Map<String, KeyItem> keys); String getOpenIdConnectUrl(); default URI getJwksJsonUrl() throws URISyntaxException { return new URI(getOpenIdConnectUrl().concat("/.well-known/jwks.json")); } default BigInteger decodeBase64UrlUInt(String value) { byte[] uintBinary = Base64.getUrlDecoder().decode(value); return new BigInteger(1, uintBinary); } default Map<String, KeyItem> openIDConnectGetKeys() throws URISyntaxException, IOException { try (InputStream input = getJwksJsonUrl().toURL().openStream()) { Map<String, KeyItem> map = new HashMap(); ByteArrayOutputStream buffer = new ByteArrayOutputStream(); while (true) { int ch = input.read(); if (ch == -1) { break; } buffer.write(ch); } ObjectMapper mapper = new ObjectMapper(); Keys keys = mapper.readValue(buffer.toByteArray(), Keys.class); for (KeyItem key: keys.keys) { map.put(key.kid, key); } return map; } } default HashMap<String, Object> verify(String idToken) throws TokenVerifyException { try { DecodedJWT jwt = JWT.decode(idToken); Map<String, KeyItem> keys = getKeys(); if (!keys.containsKey(jwt.getKeyId())) { keys = openIDConnectGetKeys(); saveKeys(keys); } KeyItem key = keys.get(jwt.getKeyId()); if (key != null) { BigInteger modulus = decodeBase64UrlUInt(key.n); BigInteger publicExponent = decodeBase64UrlUInt(key.e); KeySpec spec = new RSAPublicKeySpec(modulus, publicExponent); RSAPublicKey publicKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(spec); Algorithm algorithm = Algorithm.RSA256(publicKey, null); Verification verification = JWT.require(algorithm); verification.build().verify(jwt); ObjectMapper mapper = new ObjectMapper(); TypeReference<HashMap<String, Object>> typeRef = new TypeReference<HashMap<String, Object>>() {}; return mapper.readValue(Base64.getUrlDecoder().decode(jwt.getPayload()), typeRef); } else { throw new TokenVerifyException(String.format("Not exists %s", jwt.getKeyId())); } } catch (IOException e) { throw new TokenVerifyException(e); } catch (NoSuchAlgorithmException e) { throw new TokenVerifyException(e); } catch (URISyntaxException e) { throw new TokenVerifyException(e); } catch (InvalidKeySpecException e) { throw new TokenVerifyException(e); } } }
