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fix delete file securely method and use for delete original file

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This commit is contained in:
Vincent Breitmoser
2015-11-15 05:41:14 +01:00
parent bb79b44e7f
commit c4599798f9
3 changed files with 58 additions and 70 deletions
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45
OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpHelper.java
View File

@@ -18,23 +18,15 @@
package org.sufficientlysecure.keychain.pgp;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager.NameNotFoundException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import android.support.annotation.NonNull;
import android.text.TextUtils;
import org.sufficientlysecure.keychain.Constants;
import org.sufficientlysecure.keychain.R;
import org.sufficientlysecure.keychain.util.Log;
import org.sufficientlysecure.keychain.util.Preferences;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.security.SecureRandom;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PgpHelper {
@@ -50,35 +42,6 @@ public class PgpHelper {
".*?(-----BEGIN PGP PUBLIC KEY BLOCK-----.*?-----END PGP PUBLIC KEY BLOCK-----).*",
Pattern.DOTALL);
/**
* Deletes file securely by overwriting it with random data before deleting it.
* <p/>
* TODO: Does this really help on flash storage?
*
* @throws IOException
*/
public static void deleteFileSecurely(Context context, Progressable progressable, File file)
throws IOException {
long length = file.length();
SecureRandom random = new SecureRandom();
RandomAccessFile raf = new RandomAccessFile(file, "rws");
raf.seek(0);
raf.getFilePointer();
byte[] data = new byte[1 << 16];
int pos = 0;
String msg = context.getString(R.string.progress_deleting_securely, file.getName());
while (pos < length) {
if (progressable != null) {
progressable.setProgress(msg, (int) (100 * pos / length), 100);
}
random.nextBytes(data);
raf.write(data);
pos += data.length;
}
raf.close();
file.delete();
}
/**
* Fixing broken PGP MESSAGE Strings coming from GMail/AOSP Mail
*/

27
OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/DecryptListFragment.java
View File

@@ -800,33 +800,18 @@ public class DecryptListFragment
// we can only ever delete a file once, if we got this far either it's gone or it will never work
mCanDelete = false;
if ("file".equals(uri.getScheme())) {
File file = new File(uri.getPath());
if (file.delete()) {
try {
int deleted = FileHelper.deleteFileSecurely(activity, uri);
if (deleted > 0) {
Notify.create(activity, R.string.file_delete_ok, Style.OK).show();
} else {
Notify.create(activity, R.string.file_delete_none, Style.WARN).show();
}
return;
} catch (Exception e) {
Log.e(Constants.TAG, "exception deleting file", e);
Notify.create(activity, R.string.file_delete_exception, Style.ERROR).show();
}
if ("content".equals(uri.getScheme())) {
try {
int deleted = activity.getContentResolver().delete(uri, null, null);
if (deleted > 0) {
Notify.create(activity, R.string.file_delete_ok, Style.OK).show();
} else {
Notify.create(activity, R.string.file_delete_none, Style.WARN).show();
}
} catch (Exception e) {
Log.e(Constants.TAG, "exception deleting file", e);
Notify.create(activity, R.string.file_delete_exception, Style.ERROR).show();
}
return;
}
Notify.create(activity, R.string.file_delete_exception, Style.ERROR).show();
}
public class DecryptFilesAdapter extends RecyclerView.Adapter<ViewHolder> {

56
OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/FileHelper.java
View File

@@ -25,7 +25,9 @@ import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.security.SecureRandom;
import java.text.DecimalFormat;
import android.annotation.TargetApi;
@@ -33,7 +35,6 @@ import android.content.ActivityNotFoundException;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.Point;
@@ -41,20 +42,13 @@ import android.net.Uri;
import android.os.Build;
import android.os.Build.VERSION_CODES;
import android.os.Environment;
import android.os.ParcelFileDescriptor;
import android.provider.DocumentsContract;
import android.provider.OpenableColumns;
import android.support.v4.app.Fragment;
import android.system.ErrnoException;
import android.system.Os;
import android.system.StructStat;
import android.widget.Toast;
import org.sufficientlysecure.keychain.Constants;
import org.sufficientlysecure.keychain.R;
import static android.system.OsConstants.S_IROTH;
/** This class offers a number of helper functions for saving documents.
*
* There are three entry points here: openDocument, saveDocument and
@@ -167,6 +161,14 @@ public class FileHelper {
}
public static long getFileSize(Context context, Uri uri, long def) {
if ("file".equals(uri.getScheme())) {
long size = new File(uri.getPath()).length();
if (size == 0) {
size = def;
}
return size;
}
long size = def;
try {
Cursor cursor = context.getContentResolver().query(uri, new String[]{OpenableColumns.SIZE}, null, null, null);
@@ -261,6 +263,44 @@ public class FileHelper {
}
}
/**
* Deletes data at a URI securely by overwriting it with random data
* before deleting it. This method is fail-fast - if we can't securely
* delete the file, we don't delete it at all.
*/
public static int deleteFileSecurely(Context context, Uri uri)
throws IOException {
ContentResolver resolver = context.getContentResolver();
long lengthLeft = FileHelper.getFileSize(context, uri);
if (lengthLeft == -1) {
throw new IOException("Error opening file!");
}
SecureRandom random = new SecureRandom();
byte[] randomData = new byte[1024];
OutputStream out = resolver.openOutputStream(uri, "w");
if (out == null) {
throw new IOException("Error opening file!");
}
out = new BufferedOutputStream(out);
while (lengthLeft > 0) {
random.nextBytes(randomData);
out.write(randomData, 0, lengthLeft > randomData.length ? randomData.length : (int) lengthLeft);
lengthLeft -= randomData.length;
}
out.close();
if ("file".equals(uri.getScheme())) {
return new File(uri.getPath()).delete() ? 1 : 0;
} else {
return resolver.delete(uri, null, null);
}
}
/** Checks if external storage is mounted if file is located on external storage. */
public static boolean isStorageMounted(String file) {
if (file.startsWith(Environment.getExternalStorageDirectory().getAbsolutePath())) {