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@@ -2,25 +2,35 @@
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* Copyright (c) 2014, 2017 Sebastian Stenzel
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* All rights reserved.
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* This program and the accompanying materials are made available under the terms of the accompanying LICENSE file.
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- *
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+ *
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* Contributors:
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* Sebastian Stenzel - initial API and implementation
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******************************************************************************/
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package org.cryptomator.ui.controls;
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-import java.util.Arrays;
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-
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+import com.google.common.base.Strings;
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import javafx.scene.control.PasswordField;
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import javafx.scene.input.DragEvent;
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import javafx.scene.input.Dragboard;
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import javafx.scene.input.TransferMode;
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+import java.nio.CharBuffer;
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+import java.util.Arrays;
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+
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/**
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- * Compromise in security. While the text can be swiped, any access to the {@link #getText()} method will create a copy of the String in the heap.
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+ * Patched PasswordField that doesn't create String copies of the password in memory. Instead the password is stored in a char[] that can be swiped.
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+ *
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+ * @implNote Since {@link #setText(String)} is final, we can not override its behaviour. For that reason you should not use the {@link #textProperty()} for anything else than display purposes.
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*/
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public class SecPasswordField extends PasswordField {
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private static final char SWIPE_CHAR = ' ';
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+ private static final int INITIAL_BUFFER_SIZE = 50;
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+ private static final int GROW_BUFFER_SIZE = 50;
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+ private static final String PLACEHOLDER = "*";
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+
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+ private char[] content = new char[INITIAL_BUFFER_SIZE];
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+ private int length = 0;
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public SecPasswordField() {
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this.onDragOverProperty().set(this::handleDragOver);
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@@ -43,26 +53,54 @@ public class SecPasswordField extends PasswordField {
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event.consume();
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}
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+ @Override
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+ public void replaceText(int start, int end, String text) {
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+ int removed = end - start;
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+ int added = text.length();
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+ this.length += added - removed;
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+ growContentIfNeeded();
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+ text.getChars(0, text.length(), content, start);
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+
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+ String placeholderString = Strings.repeat(PLACEHOLDER, text.length());
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+ super.replaceText(start, end, placeholderString);
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+ }
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+
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+ private void growContentIfNeeded() {
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+ if (this.length > content.length) {
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+ char[] newContent = new char[content.length + GROW_BUFFER_SIZE];
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+ System.arraycopy(content, 0, newContent, 0, content.length);
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+ swipe();
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+ this.content = newContent;
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+ }
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+ }
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+
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+ /**
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+ * Creates a CharSequence by wrapping the password characters.
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+ *
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+ * @return A character sequence backed by the SecPasswordField's buffer (not a copy).
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+ * @implNote The CharSequence will not copy the backing char[].
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+ * Therefore any mutation to the SecPasswordField's content will mutate or eventually swipe the returned CharSequence.
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+ * @see #swipe()
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+ */
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+ @Override
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+ public CharSequence getCharacters() {
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+ return CharBuffer.wrap(content, 0, length);
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+ }
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+
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+ public void setPassword(char[] password) {
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+ swipe();
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+ content = Arrays.copyOf(password, password.length);
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+ length = password.length;
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+
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+ String placeholderString = Strings.repeat(PLACEHOLDER, password.length);
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+ setText(placeholderString);
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+ }
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+
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/**
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- * {@link #getContent()} uses a StringBuilder, which in turn is backed by a char[].
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- * The delete operation of AbstractStringBuilder closes the gap, that forms by deleting chars, by moving up the following chars.
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- * <br/>
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- * Imagine the following example with <code>pass</code> being the password, <code>x</code> being the swipe char and <code>'</code> being the offset of the char array:
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- * <ol>
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- * <li>Append filling chars to the end of the password: <code>passxxxx'</code></li>
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- * <li>Delete first 4 chars. Internal implementation will then copy subsequent chars to the position, where the deletion occured: <code>xxxx'xxxx</code></li>
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- * <li>Delete first 4 chars again, as we appended 4 chars in step 1: <code>'xxxxxx</code></li>
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- * </ol>
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+ * Destroys the stored password by overriding each character with a different character.
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*/
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public void swipe() {
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- final int pwLength = this.getContent().length();
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- final char[] fillingChars = new char[pwLength];
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- Arrays.fill(fillingChars, SWIPE_CHAR);
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- this.getContent().insert(pwLength, new String(fillingChars), false);
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- this.getContent().delete(0, pwLength, true);
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- this.getContent().delete(0, pwLength, true);
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- // previous text has now been overwritten. but we still need to update the text to trigger some property bindings:
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- this.clear();
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+ Arrays.fill(content, SWIPE_CHAR);
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}
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}
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Sebastian Stenzel