Can't create a KeyPair on Android

Question

I'm playing around with keys in android and am trying to generate a public/private cryptographic key-pair. Unfortunately I keep getting a 'KeyStoreException: Invalid key blob'.

I'm following the instructions here:

https://developer.android.com/training/articles/keystore.html

Particularly the section entitled 'Generating a New Private Key', which I feel my code copies almost verbatim:

try {
    KeyPairGenerator keyGen = KeyPairGenerator.getInstance(KeyProperties.KEY_ALGORITHM_EC, "AndroidKeyStore");
    keyGen.initialize(
        new KeyGenParameterSpec.Builder(
            keyName,
            KeyProperties.PURPOSE_SIGN | KeyProperties.PURPOSE_VERIFY)
           .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512).build()
    );

    KeyPair pair = keyGen.generateKeyPair();

} catch (NoSuchProviderException e) {
    e.printStackTrace();
} catch (InvalidAlgorithmParameterException e) {
    e.printStackTrace();
}

The value of keyName comes from user input, but I have also tried it with the value "abc".

The error I'm getting is:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.calebg.claimcreator, PID: 17389
        java.lang.IllegalStateException: Could not execute method for android:onClick
            at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
            at android.view.View.performClick(View.java:6579)
            at android.view.View.performClickInternal(View.java:6556)
            at android.view.View.access$3100(View.java:777)
            at android.view.View$PerformClick.run(View.java:25660)
            at android.os.Handler.handleCallback(Handler.java:819)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:164)
            at android.app.ActivityThread.main(ActivityThread.java:6656)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)
        Caused by: java.lang.reflect.InvocationTargetException
            at java.lang.reflect.Method.invoke(Native Method)
            at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
            at android.view.View.performClick(View.java:6579) 
            at android.view.View.performClickInternal(View.java:6556) 
            at android.view.View.access$3100(View.java:777) 
            at android.view.View$PerformClick.run(View.java:25660) 
            at android.os.Handler.handleCallback(Handler.java:819) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6656) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823) 
        Caused by: java.security.ProviderException: Failed to load generated key pair from keystore
            at android.security.keystore.AndroidKeyStoreKeyPairGeneratorSpi.loadKeystoreKeyPair(AndroidKeyStoreKeyPairGeneratorSpi.java:530)
            at android.security.keystore.AndroidKeyStoreKeyPairGeneratorSpi.generateKeyPair(AndroidKeyStoreKeyPairGeneratorSpi.java:478)
            at java.security.KeyPairGenerator$Delegate.generateKeyPair(KeyPairGenerator.java:727)
            at com.example.calebg.claimcreator.CreateKeyActivity.createKey(CreateKeyActivity.java:76)
            at java.lang.reflect.Method.invoke(Native Method) 
            at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
            at android.view.View.performClick(View.java:6579) 
            at android.view.View.performClickInternal(View.java:6556) 
            at android.view.View.access$3100(View.java:777) 
            at android.view.View$PerformClick.run(View.java:25660) 
            at android.os.Handler.handleCallback(Handler.java:819) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6656) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823) 
        Caused by: java.security.UnrecoverableKeyException: Failed to obtain X.509 form of public key
            at android.security.keystore.AndroidKeyStoreProvider.loadAndroidKeyStorePublicKeyFromKeystore(AndroidKeyStoreProvider.java:239)
            at android.security.keystore.AndroidKeyStoreProvider.loadAndroidKeyStoreKeyPairFromKeystore(AndroidKeyStoreProvider.java:278)
            at android.security.keystore.AndroidKeyStoreProvider.loadAndroidKeyStoreKeyPairFromKeystore(AndroidKeyStoreProvider.java:289)
            at android.security.keystore.AndroidKeyStoreKeyPairGeneratorSpi.loadKeystoreKeyPair(AndroidKeyStoreKeyPairGeneratorSpi.java:521)
            at android.security.keystore.AndroidKeyStoreKeyPairGeneratorSpi.generateKeyPair(AndroidKeyStoreKeyPairGeneratorSpi.java:478) 
            at java.security.KeyPairGenerator$Delegate.generateKeyPair(KeyPairGenerator.java:727) 
            at com.example.calebg.claimcreator.CreateKeyActivity.createKey(CreateKeyActivity.java:76) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
            at android.view.View.performClick(View.java:6579) 
            at android.view.View.performClickInternal(View.java:6556) 
            at android.view.View.access$3100(View.java:777) 
            at android.view.View$PerformClick.run(View.java:25660) 
            at android.os.Handler.handleCallback(Handler.java:819) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6656) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823) 
        Caused by: android.security.KeyStoreException: Invalid key blob
            at android.security.KeyStore.getKeyStoreException(KeyStore.java:823)
            at android.security.keystore.AndroidKeyStoreProvider.loadAndroidKeyStorePublicKeyFromKeystore(AndroidKeyStoreProvider.java:241)
            at android.security.keystore.AndroidKeyStoreProvider.loadAndroidKeyStoreKeyPairFromKeystore(AndroidKeyStoreProvider.java:278) 
            at android.security.keystore.AndroidKeyStoreProvider.loadAndroidKeyStoreKeyPairFromKeystore(AndroidKeyStoreProvider.java:289) 
            at android.security.keystore.AndroidKeyStoreKeyPairGeneratorSpi.loadKeystoreKeyPair(AndroidKeyStoreKeyPairGeneratorSpi.java:521) 
            at android.security.keystore.AndroidKeyStoreKeyPairGeneratorSpi.generateKeyPair(AndroidKeyStoreKeyPairGeneratorSpi.java:478) 
            at java.security.KeyPairGenerator$Delegate.generateKeyPair(KeyPairGenerator.java:727) 
            at com.example.calebg.claimcreator.CreateKeyActivity.createKey(CreateKeyActivity.java:76) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
            at android.view.View.performClick(View.java:6579) 
            at android.view.View.performClickInternal(View.java:6556) 
            at android.view.View.access$3100(View.java:777) 
            at android.view.View$PerformClick.run(View.java:25660) 
            at android.os.Handler.handleCallback(Handler.java:819) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6656) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

I'm using Android Studio 3.0.1, minSdkVersion 23, targetSdkVersion 26, and I'm testing this on a "Nexus 6 API P" virtual device.

The only other related stackoverflow question I have found (also the only google result) that looks helpful is:

android.security.KeyStoreException: Invalid key blob

However I'm not clear how to apply the answer to my situation and I'm not convinced it is a correct solution in my case (how could the keystore be locked/uninitialised when I only just initialised it? How does catching an exception and trying again solve this problem?).

Can anyone identify what I'm doing wrong?

Patrick Vigneault · Answer 1 · 2018-04-03T14:31:29.530

1

I have the same issue while trying to run my app on Android-P, I think they made some changes on the keystore See the preview, I was wondering if your physical device was running with Android P?

edited Apr 03 '18 at 14:31

answered Apr 03 '18 at 14:05

Patrick Vigneault

39
7

No it's not, but the virtual device (which isn't working) was – Caleb Apr 05 '18 at 04:19
We manage to make it working on an actual device running Android P, it seems that the issue come from the emulator. – Patrick Vigneault Apr 05 '18 at 19:11
Yes, this is the conclusion I came to as well. – Caleb Apr 08 '18 at 22:27

score 0 · Accepted Answer · answered Mar 27 '18 at 23:29

0

I tried this on a real device and it works. Don't know why, but for some reason the Android emulator is unable to create keys according to the Android documentation.

answered Mar 27 '18 at 23:29

Caleb

454
5
13

It crashes on a small number of devices. [See this post on stackoverflow](https://stackoverflow.com/questions/44469020/androidkeystore-keypairgenerator-crashes-on-small-number-of-devices) I encounter this error on OnePlus 2 devices and the Android P simulator. – Oliver Kranz Apr 18 '18 at 10:58
Even the sample app [BasicAndroidKeyStore](https://github.com/googlesamples/android-BasicAndroidKeyStore) advised in the [Keystore Android documentation](https://developer.android.com/training/articles/keystore.html) crashes. – Oliver Kranz Apr 18 '18 at 11:41

score -1 · Answer 3 · answered Mar 20 '18 at 02:22

You may try the following code, it is based on AES-128 encryption algo.

public void RandomKey(View view)
{

    int[] Keys = new int[16];
    String keyString ="";


    //reset the secret key into null
    Secret_Key="";
    SecretKey.setText(Secret_Key);

    try
    {
        KeyGenerator keyGen = KeyGenerator.getInstance("AES");
        keyGen.init(128); // 128 bit
        javax.crypto.SecretKey secretKey = keyGen.generateKey(); //generate secret key
        SKey= secretKey.getEncoded();
        // to display
        for (int i = 0; i < 16; i++)
        {

            Keys[i] = SKey[i] & 0x000000FF;//convert byte to integer
            keyString = Integer.toHexString(Keys[i]);

            if (keyString.length() < 2)
            {
                keyString="0"+keyString;
            }
            //Log.d("keys are"," "+i+keyString);
            Secret_Key = Secret_Key + " " + keyString;
        }

        SecretKey.setAllCaps(true);
        SecretKey.setText(Secret_Key);
    }

for more complete program, you can refer to this: https://github.com/aliakbarpa/AES-128_for_Android

Thanks AliAP, that gives me a SecretKey, but not a KeyPair. Also the reason I was trying to follow the android guide is that it talks about storing keystores in a place within the phone that is not easy to extract. I wonder what I need to do to ensure keys generated by Java are stored in this way? — Caleb, Mar 21 '18 at 03:41

Can't create a KeyPair on Android

3 Answers3