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If I run this code on Android P, I receive the follow exception:

private static KeyStore.PrivateKeyEntry getPrivateKeyEntry(String alias) 
 try 
 KeyStore ks = KeyStore
 .getInstance(SecurityConstants.KEYSTORE_PROVIDER_ANDROID_KEYSTORE);
 ks.load(null);
 KeyStore.Entry entry = ks.getEntry(alias, null);

 if (entry == null) 
 Log.w(TAG, "No key found under alias: " + alias);
 Log.w(TAG, "Exiting signData()...");
 return null;
 

 if (!(entry instanceof KeyStore.PrivateKeyEntry)) 
 Log.w(TAG, "Not an instance of a PrivateKeyEntry");
 Log.w(TAG, "Exiting signData()...");
 return null;
 
 return (KeyStore.PrivateKeyEntry) entry;
 catch (Exception e) 
 Log.e(TAG, e.getMessage(), e);
 return null;
 
 

Exception:

KeyStore exception
android.os.ServiceSpecificException: (code 7)
at android.os.Parcel.createException(Parcel.java:1956)
at android.os.Parcel.readException(Parcel.java:1910)
at android.os.Parcel.readException(Parcel.java:1860)
at android.security.IKeystoreService$Stub$Proxy.get(IKeystoreService.java:786)
at android.security.KeyStore.get(KeyStore.java:195)
at android.security.keystore.AndroidKeyStoreSpi.engineGetCertificateChain(AndroidKeyStoreSpi.java:118)
at java.security.KeyStoreSpi.engineGetEntry(KeyStoreSpi.java:484)
at java.security.KeyStore.getEntry(KeyStore.java:1560)
at com.phenodev.testenc.KeyStoreHelper.getPrivateKeyEntry(KeyStoreHelper.java:151)
at com.phenodev.testenc.KeyStoreHelper.encrypt(KeyStoreHelper.java:173)
at com.phenodev.testenc.KeyStoreEncryptor.encrypt(KeyStoreEncryptor.java:19)

Please help to fix it.

Finally I found a solution. It looks like since Android P (KeyStore.PrivateKeyEntry) keyStore.getEntry("alias", null) is not a proper way to get private key.

I was able to get rid of this warning by accessing private/public key this way

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);

PrivateKey privateKey = (PrivateKey) keyStore.getKey("alias", null);
PublicKey publicKey = keyStore.getCertificate("alias").getPublicKey();

In my case, the warning was still there even getting the keys as the accepted solution, but only when the key did not yet exist.

The warning comes from the getCertificate call, so, to avoid it:

KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
keyStore.load(null);

PrivateKey privateKey = (PrivateKey) keyStore.getKey("alias", null);
PublicKey publicKey = privateKey != null ? keyStore.getCertificate("alias").getPublicKey() : null;