Android signature initVerify cause exception

Question

I created a server, which can respond to a client with random points. Server code

private static void generateKeys() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException {
    ECGenParameterSpec ecSpec = new ECGenParameterSpec(SPEC);
    KeyPairGenerator g = KeyPairGenerator.getInstance("EC");
    g.initialize(ecSpec, new SecureRandom());
    KeyPair keypair = g.generateKeyPair();
    publicKey = keypair.getPublic();
    privateKey = keypair.getPrivate();
}

private static JSONObject getPoints() throws InvalidAlgorithmParameterException, NoSuchAlgorithmException {
    if(null == publicKey && null == privateKey)
        generateKeys();
    JSONObject object = new JSONObject();
    String falseSignature = "AAAaaaAAAaaa111AAAaaaAAAaaa111111AAAaaaAAAAAAAAAAAAAAAaaaaaaa111AAAAAAAAAAAAAAAAAaaaaaAAAAAAaaa1";
    try {
        Signature ecdsaSign = Signature.getInstance(ALGO);

        String pub = Base64.getEncoder().encodeToString(publicKey.getEncoded());
        List<Point> points = generatePointsList(10);
        JSONArray array = new JSONArray();
        JSONArray finalArray = array;
        points.forEach(
                i -> {
                    try {
                        ecdsaSign.initSign(privateKey);
                        JSONObject obj = new JSONObject();
                        ecdsaSign.update(i.getString().getBytes(StandardCharsets.UTF_8));
                        byte[] signature = ecdsaSign.sign();
                        String sig = Base64.getEncoder().encodeToString(signature);
                        obj.put("signature", sig);
                        obj.put("point", i.toJson());
                        finalArray.put(obj);
                    } catch (SignatureException | InvalidKeyException e) {
                        e.printStackTrace();
                    }
                }
        );
        List<Point> falsePoints = generatePointsList(5);
        falsePoints.forEach(
                i -> {
                    JSONObject obj = new JSONObject();
                    obj.put("signature", falseSignature);
                    obj.put("point", i.toJson());
                    finalArray.put(obj);
                }
        );
        object.put("publicKey", pub);
        object.put("algorithm", ALGO);
        array = shuffleJsonArray(finalArray);
        object.put("points", array);
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
        return null;
    }
    return object;
}

Point code:

public class Point {
private int x;
private int y;

public Point(int x, int y) {
    this.x = x;
    this.y = y;
}

public JSONObject toJson(){
    JSONObject obj = new JSONObject();
    obj.put("x", x);
    obj.put("y", y);
    return obj;
}

public String getString(){
    return String.format("%s%s", x, y);
}

@Override
public String toString() {
    return "Point{" +
            "x=" + x +
            ", y=" + y +
            '}';
}

Result is a json with public key and array of points and it's signatures:

{"publicKey":"MFYwEAYHKoZIzj0CAQYFK4EEAAoDQgAEcWZ5gZI6R2GZQhQ78zDWP4O6wkkc968MzrTbnwETYWKvBdAFyJzlfXmn43ISWqtmFqsSeEmUPT1vabpkbJi9SQ==","algorithm":"SHA256withECDSA","points":[{"signature":"MEYCIQC4FytGoPJOspQDHp7yjsglGuHhv16MBctUUy1VgtVznQIhANV+7drv8aXinT7IBT7apaVlIFE9/Gz/UzPRkj+1dUp4","point":{"x":141,"y":33}},{"signature":"AAAaaaAAAaaa111AAAaaaAAAaaa111111AAAaaaAAAAAAAAAAAAAAAaaaaaaa111AAAAAAAAAAAAAAAAAaaaaaAAAAAAaaa1","point":{"x":88,"y":41}},{"signature":"MEUCIQDaCibfFoh9TVSVZVJuOkT/GTssjEFjYoIn0UdHg4wtTAIgf7Pa52udA4UVIWAPdM5m3wnkgo3/LqT8Q/qQs0USMGU=","point":{"x":119,"y":179}}}]

Android client code on kotlin:

public fun getPoints(){
    coroutineScope.launch {
        val getPointsInfoDeferred = executeAsync { getPoints()}
        try {
            _status.value = ServerApiStatus.LOADING
            val points = getPointsInfoDeferred.await()
            algo = points.algorithm
            publicKey = getPubKey(points.publicKey)
            _pointsProp.value = points.points.map { ParselableInfo(points.publicKey,
                checkPoints(it),
                it) }
            _status.value = ServerApiStatus.COMPLETED
        }catch (e: Exception){
            _status.value = ServerApiStatus.ERROR
            Log.i("OVERVIEW MODEL", "some exception: ${e.message}")
            _pointsProp.value = listOf()
        }
    }
}

private fun getPubKey(pubkey:String): PublicKey {
    val publicKeySpec: EncodedKeySpec = X509EncodedKeySpec(Base64.decode(pubkey, Base64.DEFAULT))
    val keyFactory: KeyFactory = KeyFactory.getInstance("EC")
    return keyFactory.generatePublic(publicKeySpec)
}

private fun getPointString(x: Int, y: Int): String{
    return "$x$y"
}

private fun checkPoints(pointWithSign: PointWithSignature): Boolean{
    val sign: Signature = Signature.getInstance(algo)
    val point = pointWithSign.point
    return try {
        val a = String(publicKey.encoded)
        sign.initVerify(publicKey)
        sign.update(getPointString(point.x, point.y).toByteArray(StandardCharsets.UTF_8))
        return sign.verify(pointWithSign.signature.toByteArray(StandardCharsets.UTF_8))

    } catch (e: java.lang.Exception) {
        false
    }
}

So "sign.initVerify(publicKey)" line cause Exception - parsing public key error, even the Public key object was created in function 'getPubKey'. I dont know where am i wrong.

StackTrace:

java.security.InvalidKeyException: com.android.org.conscrypt.OpenSSLX509CertificateFactory$ParsingException: Error parsing public key
at com.android.org.conscrypt.OpenSSLKey.fromPublicKey(OpenSSLKey.java:251)
at com.android.org.conscrypt.OpenSSLSignature.engineInitVerify(OpenSSLSignature.java:215)
at java.security.Signature$Delegate.init(Signature.java:1354)
at java.security.Signature$Delegate.chooseProvider(Signature.java:1310)
at java.security.Signature$Delegate.engineInitVerify(Signature.java:1374)
at java.security.Signature.initVerify(Signature.java:601)
at com.example.disserclient.overview.OverviewModel.checkPoints(OverviewModel.kt:91)
at com.example.disserclient.overview.OverviewModel.access$checkPoints(OverviewModel.kt:22)
at com.example.disserclient.overview.OverviewModel$getPoints$1.invokeSuspend(OverviewModel.kt:57)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:241)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7076)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)
Caused by: com.android.org.conscrypt.OpenSSLX509CertificateFactory$ParsingException: Error parsing public key
at com.android.org.conscrypt.NativeCrypto.EVP_parse_public_key(Native Method)
at com.android.org.conscrypt.OpenSSLKey.fromPublicKey(OpenSSLKey.java:249)

Answer 1

So i found the solution. As @Maarten - reinstate Monica suggested, i tried to use Bouncy castle provider. And it works! On server side before keypair creation I added this line:

Security.insertProviderAt(new BouncyCastleProvider(), 1);

On client side I did some changes:

val keyFactory: KeyFactory = KeyFactory.getInstance("EC", castleProvider)

and

val sign: Signature = Signature.getInstance(points.algorithm, castleProvider)

castleProvider is BouncyCastleProvider from

'org.bouncycastle', name: 'bcprov-jdk15on', version: '1.64'

Also i forgot about Base64 encoding on server side, so I changed sign verifying:

sign.verify(Base64.decode(pointWithSign.signature, Base64.DEFAULT))