SSH Agent: Add support for generating SSH keys

Supported key types are RSA, ECDSA and Ed25519.

Includes tests to compare writing out keys produce the exact same private key if read from OpenSSH format and tests against ssh-agent to ensure all no generated key is rejected.

src/sshagent/OpenSSHKeyGenDialog.h

@@ -0,0 +1,48 @@
+/*
+ *  Copyright (C) 2021 Team KeePassXC <team@keepassxc.org>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 2 or (at your option)
+ *  version 3 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef KEEPASSXC_OPENSSHKEYGENDIALOG_H
+#define KEEPASSXC_OPENSSHKEYGENDIALOG_H
+
+#include <QDialog>
+class OpenSSHKey;
+
+namespace Ui
+{
+    class OpenSSHKeyGenDialog;
+}
+
+class OpenSSHKeyGenDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit OpenSSHKeyGenDialog(QWidget* parent = nullptr);
+    ~OpenSSHKeyGenDialog() override;
+
+    void accept() override;
+    void setKey(OpenSSHKey* key);
+
+private slots:
+    void typeChanged();
+
+private:
+    QScopedPointer<Ui::OpenSSHKeyGenDialog> m_ui;
+    OpenSSHKey* m_key;
+};
+
+#endif // KEEPASSXC_OPENSSHKEYGENDIALOG_H