[SSH] Increase bit-size of generated RSA and DSA keys

This implementation allows to generate RSA keys with 4096 bits and DSA keys with 3072 bits. (DSA does not support 4096 bits or higher within the key algorithm)
Originally generates 1024 bits for RSA and DSA keys.

Fixes #1464

team/bundles/org.eclipse.jsch.ui/src/org/eclipse/jsch/internal/ui/preference/PreferencePage.java

@@ -89,6 +89,8 @@ public class PreferencePage extends org.eclipse.jface.preference.PreferencePage
 		implements IWorkbenchPreferencePage{
 
 	private static final String SSH2_PREFERENCE_PAGE_CONTEXT="org.eclipse.jsch.ui.ssh2_preference_page_context"; //$NON-NLS-1$
+	private static final int RSA_KEY_SIZE = 4096;
+	private static final int DSA_KEY_SIZE = 3072;
 
 	private Label ssh2HomeLabel;
 	private Label privateKeyLabel;
@@ -494,10 +496,11 @@ else if(e.widget==keyGenerateRSA){
 
 					final KeyPair[] _kpair=new KeyPair[1];
 					final int __type=type;
+					int keySize = type == KeyPair.RSA ? RSA_KEY_SIZE : DSA_KEY_SIZE;
 					final JSchException[] _e=new JSchException[1];
 					BusyIndicator.showWhile(getShell().getDisplay(), () -> {
 						try {
-							_kpair[0] = KeyPair.genKeyPair(getJSch(), __type);
+							_kpair[0] = KeyPair.genKeyPair(getJSch(), __type, keySize);
 						} catch (JSchException e1) {
 							_e[0] = e1;
 						}
@@ -508,7 +511,7 @@ else if(e.widget==keyGenerateRSA){
 					kpair=_kpair[0];
 
 					ByteArrayOutputStream out=new ByteArrayOutputStream();
-					kpairComment=_type+"-1024"; //$NON-NLS-1$
+					kpairComment = _type + "-" + keySize; //$NON-NLS-1$
 					kpair.writePublicKey(out, kpairComment);
 					out.close();
 					publicKeyText.setText(out.toString());