Android Keystore Error "could not generate key in keystore"

Question

I get an error trying to generate a key for certain devices. I'm able to reproduce the error on a Samsung Galaxy Note running 4.4.2.

java.lang.IllegalStateException: could not generate key in keystore
        at android.security.AndroidKeyPairGenerator.generateKeyPair(AndroidKeyPairGenerator.java:100)
        at java.security.KeyPairGenerator$KeyPairGeneratorImpl.generateKeyPair(KeyPairGenerator.java:275)
        at com.eric.demo.MainActivity.generateKeyPair(MainActivity.java:65)
        at com.eric.demo.MainActivity.onClickButton(MainActivity.java:43)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at android.view.View$1.onClick(View.java:3964)
        at android.view.View.performClick(View.java:4640)
        at android.view.View$PerformClick.run(View.java:19421)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5476)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
        at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
        at dalvik.system.NativeStart.main(Native Method)

I created a small app to only generate a key by copying the code line by line from the Android developer page https://developer.android.com/training/articles/keystore.html under "Generating a New Private Key."

 public void onClickButton (View view) {
    try {
        generateKeyPair(this, "test3");
    } catch (Exception e){
        Log.wtf("exception", e);
    }
}

private void generateKeyPair(Context context, String alias)
    throws Exception {
    Calendar cal = Calendar.getInstance();
    Date now = cal.getTime();
    cal.add(Calendar.YEAR, 1);
    Date end = cal.getTime();

    KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA", "AndroidKeyStore");
    kpg.initialize(new KeyPairGeneratorSpec.Builder(getApplicationContext())
            .setAlias(alias)
            .setStartDate(now)
            .setEndDate(end)
            .setSerialNumber(BigInteger.valueOf(1))
            .setSubject(new X500Principal("CN=test3"))
            .build());

    KeyPair kp = kpg.generateKeyPair();
}

The error seems to occur in kpg.generateKeyPair(), inside AndroidKeyPairGenerator.java:

if (!mKeyStore.generate(privateKeyAlias, KeyStore.UID_SELF, keyType,
        mSpec.getKeySize(), mSpec.getFlags(), args)) {
    throw new IllegalStateException("could not generate key in keystore");
}

and in KeyStore.java:

public boolean generate(String key, int uid, int keyType, int keySize, int flags,
        byte[][] args) {
    try {
        return mBinder.generate(key, uid, keyType, keySize, flags, args) == NO_ERROR;
    } catch (RemoteException e) {
        Log.w(TAG, "Cannot connect to keystore", e);
        return false;
    }
}

The mBinder.generate() call seems to return 2 which means the keystore is locked?

// ResponseCodes
public static final int NO_ERROR = 1;
public static final int LOCKED = 2;
public static final int UNINITIALIZED = 3;
public static final int SYSTEM_ERROR = 4;
public static final int PROTOCOL_ERROR = 5;
public static final int PERMISSION_DENIED = 6;
public static final int KEY_NOT_FOUND = 7;
public static final int VALUE_CORRUPTED = 8;
public static final int UNDEFINED_ACTION = 9;
public static final int WRONG_PASSWORD = 10;

The error might be somewhat related to this issue with the keystore https://code.google.com/p/android/issues/detail?id=177459&q=could%20not%20generate%20key%20in%20keystore&colspec=ID%20Type%20Status%20Owner%20Summary%20Stars

A few things I've tried individually and combinations of the following:
1. Setting encryption required. The result is another error: "Android keystore must be in initialized and unlocked state if encryption is required"
2. Setting a lock screen (pattern, PIN, NONE, password, swipe). Same behavior
3. Programmatically attempting to unlock or reset the credential storage with startActivity(new Intent("com.android.credentials.UNLOCK")); or startActivity(new Intent("com.android.credentials.RESET")); Attempting to unlock shows a "enter password for credential storage" message, in which no reasonable password works, and even clearing the credentials doesn't help.

Answer 1

public class EncryptionApi18AndAbove{
    private Context context;
    private KeyStore keyStore;
    private static String alias = "alias";

    public EncryptionApi18AndAbove(Context context) {
        this.context = context;
        try {
            keyStore = KeyStore.getInstance("AndroidKeyStore");
            keyStore.load(null);
        } catch (Exception e) {
           // bla bla
        }
    }

    private String createNewKeys(String alias, Context context) {
        try {
            if (!keyStore.containsAlias(alias)) {
                Calendar start = Calendar.getInstance();
                Calendar end = Calendar.getInstance();
                end.add(Calendar.YEAR, 1);
                KeyPairGeneratorSpec spec = new KeyPairGeneratorSpec.Builder(context)
                        .setAlias(alias)
                        .setSubject(new X500Principal("CN=Sample Name, O=Android Authority"))
                        .setSerialNumber(BigInteger.ONE)
                        .setStartDate(start.getTime())
                        .setEndDate(end.getTime())
                        .build();
                KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "AndroidKeyStore");
                generator.initialize(spec);
                generator.initialize(spec);
                generator.generateKeyPair();
            }
        } catch (Exception e) {
            //bla bla
        }
        return alias;
    }

    @Override
    public String encrypt(String text) {
        if (text == null || text.length() == 0) {
            return text;
        }
        try {
            KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry) keyStore.getEntry(createNewKeys(alias, context), null);
            PublicKey publicKey = privateKeyEntry.getCertificate().getPublicKey();
            Cipher inCipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            inCipher.init(Cipher.ENCRYPT_MODE, publicKey);

            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            CipherOutputStream cipherOutputStream = new CipherOutputStream(
                    outputStream, inCipher);
            cipherOutputStream.write(text.getBytes("UTF-8"));
            cipherOutputStream.close();

            return Base64.encodeToString(outputStream.toByteArray(), Base64.DEFAULT);
        } catch (Exception e) {
            //bla bla
        }
        return text;
    }

    @Override
    public String decrypt(String text) {
        if (text == null || text.length() == 0) {
            return text;
        }
        try {
            KeyStore.PrivateKeyEntry privateKeyEntry = (KeyStore.PrivateKeyEntry) keyStore.getEntry(createNewKeys(alias, context), null);
            PrivateKey privateKey = privateKeyEntry.getPrivateKey();

            Cipher output = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            output.init(Cipher.DECRYPT_MODE, privateKey);

            CipherInputStream cipherInputStream = new CipherInputStream(
                    new ByteArrayInputStream(Base64.decode(text, Base64.DEFAULT)), output);
            ArrayList<Byte> values = new ArrayList<>();
            int nextByte;
            while ((nextByte = cipherInputStream.read()) != -1) {
                values.add((byte) nextByte);
            }
            byte[] bytes = new byte[values.size()];
            for (int i = 0; i < bytes.length; i++) {
                bytes[i] = values.get(i).byteValue();
            }
            return new String(bytes, 0, bytes.length, "UTF-8");

        } catch (Exception e) {
            // bla bla
        }
        return text;
    }
}

You can use this class . This is works min SDK 18 and above. You can create Android Keystore key , decrypt and encrypt simple text.

Answer 2

While I don't know the full answer, I can help continue your search. The binder implementation on the other side of mBinder is the native keystore. If I recall fully, it's behavior is to either 1) support key operations at a software level, or 2) delegate to a OEM-provided keymaster library that (presumably) interfaces to the OEM's hardware-backed keystore. More info on this here, here, and here.

Note: I'll forgo SO's normal policy of pulling the external link content into the answer, since I'm linking you out to three articles that are all >1 page and it seems a bit ridiculous to post a 6-page answer ;-)