com.google.crypto.tink.integration.android.SharedPrefKeysetWriter Maven / Gradle / Ivy
// Copyright 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////
package com.google.crypto.tink.integration.android;
import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import com.google.crypto.tink.KeysetWriter;
import com.google.crypto.tink.proto.EncryptedKeyset;
import com.google.crypto.tink.proto.Keyset;
import com.google.crypto.tink.subtle.Hex;
import java.io.IOException;
/**
* A {@link KeysetWriter} that can write keysets to private shared preferences on Android.
*
* We do not recommend new uses of this class. Instead, if you want to store a Tink keyset in
* shared preferences, serialize the keyset using TinkProtoKeysetFormat, and write it hex-encoded
* into your SharedPreferences manually.
*
*
For example, to write an encrypted keyset to the shared preferences, you can replace this:
*
*
{@code
* keysetHandle.write(
* new SharedPrefKeysetWriter(
* ApplicationProvider.getApplicationContext(), keysetName, null),
* keysetEncryptionAead);
* }
*
* with this:
*
*
{@code
* byte[] encryptedKeyset =
* TinkProtoKeysetFormat.serializeEncryptedKeyset(
* handle, keysetEncryptionAead, new byte[0]);
* SharedPreferences.Editor editor =
* PreferenceManager.getDefaultSharedPreferences(
* ApplicationProvider.getApplicationContext().getApplicationContext())
* .edit();
* boolean success = editor.putString(keysetName, Hex.encode(encryptedKeyset)).commit();
* }
*
* and to write an unencrypted keyset to the shared preferences, you can replace this:
*
*
{@code
* CleartextKeysetHandle.write(
* handle,
* new SharedPrefKeysetWriter(
* ApplicationProvider.getApplicationContext(), keysetName, null));
* }
*
* with this:
*
*
{@code
* byte[] serializedKeyset =
* TinkProtoKeysetFormat.serializeKeyset(handle, InsecureSecretKeyAccess.get());
* SharedPreferences.Editor editor =
* PreferenceManager.getDefaultSharedPreferences(
* ApplicationProvider.getApplicationContext().getApplicationContext())
* .edit();
* boolean success = editor.putString(keysetName, Hex.encode(serializedKeyset)).commit();
* }
*/
public final class SharedPrefKeysetWriter implements KeysetWriter {
private final SharedPreferences.Editor editor;
private final String keysetName;
/**
* Creates a {@link KeysetReader} that hex-encodes and writes keysets to the preference
* name {@code keysetName} in the private shared preferences file {@code prefFileName}.
*
*If {@code prefFileName} is null, uses the default shared preferences file.
*
* @throws IOException if cannot write the keyset
* @throws IllegalArgumentException if {@code keysetName} is null
*/
public SharedPrefKeysetWriter(Context context, String keysetName, String prefFileName) {
if (keysetName == null) {
throw new IllegalArgumentException("keysetName cannot be null");
}
this.keysetName = keysetName;
Context appContext = context.getApplicationContext();
if (prefFileName == null) {
editor = PreferenceManager.getDefaultSharedPreferences(appContext).edit();
} else {
editor = appContext.getSharedPreferences(prefFileName, Context.MODE_PRIVATE).edit();
}
}
@Override
public void write(Keyset keyset) throws IOException {
boolean success = editor.putString(keysetName, Hex.encode(keyset.toByteArray())).commit();
if (!success) {
throw new IOException("Failed to write to SharedPreferences");
}
}
@Override
public void write(EncryptedKeyset keyset) throws IOException {
boolean success = editor.putString(keysetName, Hex.encode(keyset.toByteArray())).commit();
if (!success) {
throw new IOException("Failed to write to SharedPreferences");
}
}
}