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Added possibility to enter custom key length. Added key length limitations, according to issue #102 and SpongyCastle specification.

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This commit is contained in:
gogowitczak
2014-04-07 16:31:38 +02:00
parent 3c8be8bf85
commit fc0c084a62
4 changed files with 149 additions and 22 deletions
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148
OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/CreateKeyDialogFragment.java
View File

@@ -23,11 +23,15 @@ import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.support.v4.app.FragmentActivity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import org.sufficientlysecure.keychain.Id;
import org.sufficientlysecure.keychain.R;
import org.sufficientlysecure.keychain.util.Choice;
@@ -45,6 +49,10 @@ public class CreateKeyDialogFragment extends DialogFragment {
private int mNewKeySize;
private Choice mNewKeyAlgorithmChoice;
private OnAlgorithmSelectedListener mAlgorithmSelectedListener;
private Spinner mAlgorithmSpinner;
private Spinner mKeySizeSpinner;
private TextView mCustomKeyTextView;
private EditText mCustomKeyEditText;
public void setOnAlgorithmSelectedListener(OnAlgorithmSelectedListener listener) {
mAlgorithmSelectedListener = listener;
@@ -77,7 +85,7 @@ public class CreateKeyDialogFragment extends DialogFragment {
boolean wouldBeMasterKey = (childCount == 0);
final Spinner algorithm = (Spinner) view.findViewById(R.id.create_key_algorithm);
mAlgorithmSpinner = (Spinner) view.findViewById(R.id.create_key_algorithm);
ArrayList<Choice> choices = new ArrayList<Choice>();
choices.add(new Choice(Id.choice.algorithm.dsa, getResources().getString(
R.string.dsa)));
@@ -92,38 +100,53 @@ public class CreateKeyDialogFragment extends DialogFragment {
ArrayAdapter<Choice> adapter = new ArrayAdapter<Choice>(context,
android.R.layout.simple_spinner_item, choices);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
algorithm.setAdapter(adapter);
mAlgorithmSpinner.setAdapter(adapter);
// make RSA the default
for (int i = 0; i < choices.size(); ++i) {
if (choices.get(i).getId() == Id.choice.algorithm.rsa) {
algorithm.setSelection(i);
mAlgorithmSpinner.setSelection(i);
break;
}
}
final Spinner keySize = (Spinner) view.findViewById(R.id.create_key_size);
mKeySizeSpinner = (Spinner) view.findViewById(R.id.create_key_size);
ArrayAdapter<CharSequence> keySizeAdapter = ArrayAdapter.createFromResource(
context, R.array.key_size_spinner_values,
android.R.layout.simple_spinner_item);
keySizeAdapter
.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
keySize.setAdapter(keySizeAdapter);
keySize.setSelection(3); // Default to 4096 for the key length
mKeySizeSpinner.setAdapter(keySizeAdapter);
mKeySizeSpinner.setSelection(3); // Default to 4096 for the key length
mCustomKeyTextView = (TextView) view.findViewById(R.id.custom_key_size_label);
mCustomKeyEditText = (EditText) view.findViewById(R.id.custom_key_size_input);
final AdapterView.OnItemSelectedListener customKeySelectedLisener = new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
final String selectedItemString = (String) parent.getSelectedItem();
final String customLengthString = getResources().getString(R.string.key_size_custom);
final boolean customSelected = customLengthString.equals(selectedItemString);
final int visibility = customSelected ? View.VISIBLE : View.GONE;
mCustomKeyEditText.setVisibility(visibility);
mCustomKeyTextView.setVisibility(visibility);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
};
dialog.setPositiveButton(android.R.string.ok,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface di, int id) {
di.dismiss();
try {
final String selectedItem = (String) keySize.getSelectedItem();
mNewKeySize = Integer.parseInt(selectedItem);
} catch (NumberFormatException e) {
mNewKeySize = 0;
}
mNewKeyAlgorithmChoice = (Choice) algorithm.getSelectedItem();
mNewKeyAlgorithmChoice = (Choice) mAlgorithmSpinner.getSelectedItem();
mNewKeySize = getProperKeyLength(mNewKeyAlgorithmChoice.getId(), getSelectedKeyLength());
mAlgorithmSelectedListener.onAlgorithmSelected(mNewKeyAlgorithmChoice, mNewKeySize);
}
});
}
);
dialog.setCancelable(true);
dialog.setNegativeButton(android.R.string.cancel,
@@ -138,11 +161,9 @@ public class CreateKeyDialogFragment extends DialogFragment {
final AdapterView.OnItemSelectedListener weakRsaListener = new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
final Choice selectedAlgorithm = (Choice) algorithm.getSelectedItem();
final int selectedKeySize = Integer.parseInt((String) keySize.getSelectedItem());
final boolean isWeakRsa = (selectedAlgorithm.getId() == Id.choice.algorithm.rsa &&
selectedKeySize <= 1024);
alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(!isWeakRsa);
if (mKeySizeSpinner == parent)
customKeySelectedLisener.onItemSelected(parent, view, position, id);
setOkButtonAvailability(alertDialog);
}
@Override
@@ -150,10 +171,93 @@ public class CreateKeyDialogFragment extends DialogFragment {
}
};
keySize.setOnItemSelectedListener(weakRsaListener);
algorithm.setOnItemSelectedListener(weakRsaListener);
mCustomKeyEditText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
setOkButtonAvailability(alertDialog);
}
});
mKeySizeSpinner.setOnItemSelectedListener(weakRsaListener);
mAlgorithmSpinner.setOnItemSelectedListener(weakRsaListener);
return alertDialog;
}
private int getSelectedKeyLength() {
final String selectedItemString = (String) mKeySizeSpinner.getSelectedItem();
final String customLengthString = getResources().getString(R.string.key_size_custom);
final boolean customSelected = customLengthString.equals(selectedItemString);
String keyLengthString = customSelected ? mCustomKeyEditText.getText().toString() : selectedItemString;
int keySize = 0;
try {
keySize = Integer.parseInt(keyLengthString);
} catch (NumberFormatException e) {
keySize = 0;
}
return keySize;
}
/**
* <h3>RSA</h3>
* <p>for RSA algorithm, key length must be greater than 1024 (according to
* <a href="https://github.com/open-keychain/open-keychain/issues/102">#102</a>). Possibility to generate keys bigger
* than 8192 bits is currently disabled, because it's almost impossible to generate them on a mobile device (check
* <a href="http://www.javamex.com/tutorials/cryptography/rsa_key_length.shtml">RSA key length plot</a> and
* <a href="http://www.keylength.com/">Cryptographic Key Length Recommendation</a>). Also, key length must be a
* multiplicity of 8.</p>
* <h3>ElGamal</h3>
* <p>For ElGamal algorithm, supported key lengths are 1536, 2048, 3072, 4096 or 8192 bits.</p>
* <h3>DSA</h3>
* <p>For DSA algorithm key length must be between 512 and 1024. Also, it must me dividable by 64.</p>
*
* @return correct key length, according to SpongyCastle specification. Returns <code>-1</code>, if key length is
* inappropriate.
*/
private int getProperKeyLength(int algorithmId, int currentKeyLength) {
final int[] elGamalSupportedLengths = {1536, 2048, 3072, 4096, 8192};
int properKeyLength = -1;
switch (algorithmId) {
case Id.choice.algorithm.rsa:
if (currentKeyLength > 1024 && currentKeyLength <= 8192) {
properKeyLength = currentKeyLength + ((8 - (currentKeyLength % 8)) % 8);
}
break;
case Id.choice.algorithm.elgamal:
int[] elGammalKeyDiff = new int[elGamalSupportedLengths.length];
for (int i = 0; i < elGamalSupportedLengths.length; i++)
elGammalKeyDiff[i] = Math.abs(elGamalSupportedLengths[i] - currentKeyLength);
int minimalValue = Integer.MAX_VALUE;
int minimalIndex = -1;
for (int i = 0; i < elGammalKeyDiff.length; i++)
if (elGammalKeyDiff[i] <= minimalValue) {
minimalValue = elGammalKeyDiff[i];
minimalIndex = i;
}
properKeyLength = elGamalSupportedLengths[minimalIndex];
break;
case Id.choice.algorithm.dsa:
if (currentKeyLength >= 512 && currentKeyLength <= 1024) {
properKeyLength = currentKeyLength + ((64 - (currentKeyLength % 64)) % 64);
}
break;
}
return properKeyLength;
}
private void setOkButtonAvailability(AlertDialog alertDialog) {
final Choice selectedAlgorithm = (Choice) mAlgorithmSpinner.getSelectedItem();
final int selectedKeySize = getSelectedKeyLength(); //Integer.parseInt((String) mKeySizeSpinner.getSelectedItem());
final int properKeyLength = getProperKeyLength(selectedAlgorithm.getId(), selectedKeySize);
alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(properKeyLength > 0);
}
}

18
OpenKeychain/src/main/res/layout/create_key_dialog.xml
View File

@@ -56,6 +56,24 @@
android:gravity="right"
android:padding="4dp" />
</TableRow>
<TextView
android:id="@+id/custom_key_size_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:padding="4dp"
android:text="@string/key_size_custom_info"
android:visibility="gone"/>
<EditText
android:id="@+id/custom_key_size_input"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:inputType="number"
android:visibility="gone"/>
</TableLayout>
</ScrollView>

2
OpenKeychain/src/main/res/values/arrays.xml
View File

@@ -34,6 +34,8 @@
<item>@string/key_size_1024</item>
<item>@string/key_size_2048</item>
<item>@string/key_size_4096</item>
<item>@string/key_size_8192</item>
<item>@string/key_size_custom</item>
</string-array>
<string-array name="import_action_list" translatable="false">
<item>@string/menu_import_from_key_server</item>

3
OpenKeychain/src/main/res/values/strings.xml
View File

@@ -378,6 +378,9 @@
<string name="key_size_1024">1024</string>
<string name="key_size_2048">2048</string>
<string name="key_size_4096">4096</string>
<string name="key_size_8192">8192</string>
<string name="key_size_custom">Custom key size</string>
<string name="key_size_custom_info">Type custom key length (in bits):</string>
<!-- compression -->
<string name="compression_fast">fast</string>