diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6e6475ffd..292980865 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,114 +1,120 @@
 cmake_minimum_required(VERSION 3.16 FATAL_ERROR)
 set(PIM_VERSION "5.17.44")
 
 project(libkleo VERSION ${PIM_VERSION})
 
 set(KF5_MIN_VERSION "5.82.0")
 
 if (WIN32)
   set(KF5_WANT_VERSION "5.70.0")
 else ()
   set(KF5_WANT_VERSION ${KF5_MIN_VERSION})
 endif ()
 
 find_package(ECM ${KF5_WANT_VERSION} CONFIG REQUIRED)
 set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH})
 
 include(KDEInstallDirs)
 include(KDECMakeSettings)
 include(KDEFrameworkCompilerSettings NO_POLICY_SCOPE)
 
 include(GenerateExportHeader)
 include(ECMSetupVersion)
 include(ECMGenerateHeaders)
 include(ECMGeneratePriFile)
 
 include(FeatureSummary)
 include(ECMQtDeclareLoggingCategory)
 
 set(LIBKLEO_LIB_VERSION ${PIM_VERSION})
 set(QT_REQUIRED_VERSION "5.15.0")
 set(KDEPIMTEXTEDIT_VERSION "5.17.40")
 
 find_package(Qt5 ${QT_REQUIRED_VERSION} CONFIG REQUIRED Widgets)
 find_package(KF5I18n ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5Config ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5WidgetsAddons ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5Completion ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5CoreAddons ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5Codecs ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5ItemModels ${KF5_WANT_VERSION} CONFIG REQUIRED)
 find_package(KF5PimTextEdit ${KDEPIMTEXTEDIT_VERSION} CONFIG)
 
 set(GPGMEPP_LIB_VERSION "1.13.1")
 find_package(Gpgmepp ${GPGMEPP_LIB_VERSION} CONFIG REQUIRED)
 set_package_properties(Gpgmepp PROPERTIES DESCRIPTION "GpgME++ Library" URL "https://www.gnupg.org" TYPE REQUIRED PURPOSE "GpgME++ is required for OpenPGP support")
 find_package(QGpgme ${GPGMEPP_LIB_VERSION} CONFIG REQUIRED)
 message(STATUS "GPGME Version ${Gpgmepp_VERSION}")
+if (Gpgmepp_VERSION VERSION_GREATER_EQUAL "1.15.2")
+    set(GPGMEPP_SUPPORTS_TRUST_SIGNATURES 1)
+endif()
 
 find_package(Boost 1.34.0)
 set_package_properties(Boost PROPERTIES DESCRIPTION "Boost C++ Libraries" URL "https://www.boost.org" TYPE REQUIRED PURPOSE "Boost is required for building most KDEPIM applications")
 
 
 set_package_properties(KF5PimTextEdit PROPERTIES DESCRIPTION
                        "A textedit with PIM-specific features."
                        URL "https://commits.kde.org/kpimtextedit"
                        TYPE OPTIONAL PURPOSE "Improved audit log viewer.")
 
 ecm_setup_version(PROJECT VARIABLE_PREFIX LIBKLEO
                         VERSION_HEADER "${CMAKE_CURRENT_BINARY_DIR}/libkleo_version.h"
                         PACKAGE_VERSION_FILE "${CMAKE_CURRENT_BINARY_DIR}/KF5LibkleoConfigVersion.cmake"
                         SOVERSION 5
 )
 
 ########### Targets ###########
 add_definitions(-DQT_DISABLE_DEPRECATED_BEFORE=0)
 #add_definitions(-DQT_DISABLE_DEPRECATED_BEFORE=0x050f00)
 add_definitions(-DKF_DISABLE_DEPRECATED_BEFORE_AND_AT=0x055300)
 remove_definitions(-DQT_NO_FOREACH)
 add_definitions(-DQT_NO_EMIT)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 ########### CMake Config Files ###########
 set(CMAKECONFIG_INSTALL_DIR "${KDE_INSTALL_CMAKEPACKAGEDIR}/KF5Libkleo")
 
 configure_package_config_file(
   "${CMAKE_CURRENT_SOURCE_DIR}/KF5LibkleoConfig.cmake.in"
   "${CMAKE_CURRENT_BINARY_DIR}/KF5LibkleoConfig.cmake"
   INSTALL_DESTINATION  ${CMAKECONFIG_INSTALL_DIR}
 )
 
 install(FILES
   "${CMAKE_CURRENT_BINARY_DIR}/KF5LibkleoConfig.cmake"
   "${CMAKE_CURRENT_BINARY_DIR}/KF5LibkleoConfigVersion.cmake"
   DESTINATION "${CMAKECONFIG_INSTALL_DIR}"
   COMPONENT Devel
 )
 
 install(EXPORT KF5LibkleoTargets DESTINATION "${CMAKECONFIG_INSTALL_DIR}" FILE KF5LibkleoTargets.cmake NAMESPACE KF5::)
 
 install(FILES
    ${CMAKE_CURRENT_BINARY_DIR}/libkleo_version.h
   DESTINATION ${KDE_INSTALL_INCLUDEDIR_KF5} COMPONENT Devel
 )
 
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/config-libkleo.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/config-libkleo.h)
+include_directories(${CMAKE_CURRENT_BINARY_DIR})
+
 option(USE_UNITY_CMAKE_SUPPORT "Use UNITY cmake support (speedup compile time)" OFF)
 
 set(COMPILE_WITH_UNITY_CMAKE_SUPPORT OFF)
 if (USE_UNITY_CMAKE_SUPPORT)
     set(COMPILE_WITH_UNITY_CMAKE_SUPPORT ON)
 endif()
 
 
 add_subdirectory(src)
 if (BUILD_TESTING)
     add_subdirectory(autotests)
 endif()
 
 ecm_qt_install_logging_categories(
         EXPORT LIBKLEO
         FILE libkleo.categories
         DESTINATION ${KDE_INSTALL_LOGGINGCATEGORIESDIR}
         )
 ki18n_install(po)
 feature_summary(WHAT ALL FATAL_ON_MISSING_REQUIRED_PACKAGES)
diff --git a/config-libkleo.h.cmake b/config-libkleo.h.cmake
new file mode 100644
index 000000000..cec4fc9cd
--- /dev/null
+++ b/config-libkleo.h.cmake
@@ -0,0 +1,2 @@
+/* Defined if GpgME++ supports trust signatures */
+#cmakedefine GPGMEPP_SUPPORTS_TRUST_SIGNATURES 1
diff --git a/src/models/useridlistmodel.cpp b/src/models/useridlistmodel.cpp
index a5b0e42c1..89d9f908b 100644
--- a/src/models/useridlistmodel.cpp
+++ b/src/models/useridlistmodel.cpp
@@ -1,347 +1,360 @@
 /* -*- mode: c++; c-basic-offset:4 -*-
     models/useridlistmodel.cpp
 
     This file is part of Kleopatra, the KDE keymanager
     SPDX-FileCopyrightText: 2007 Klarälvdalens Datakonsult AB
     SPDX-FileCopyrightText: 2016 Andre Heinecke <aheinecke@gnupg.org>
+    SPDX-FileCopyrightText: 2021 g10 Code GmbH
+    SPDX-FileContributor: Ingo Klöcker <dev@ingo-kloecker.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
+#include <config-libkleo.h>
+
 #include "useridlistmodel.h"
 
 #include "keycache.h"
 #include "utils/formatting.h"
 
 #include <KLocalizedString>
 
 #include <QVariant>
 #include <QIcon>
 
 #include <gpgme++/key.h>
 
 #include <gpgme++/gpgmepp_version.h>
 #if GPGMEPP_VERSION >= 0x10E00 // 1.14.0
 # define GPGME_HAS_REMARKS
 #endif
 #if GPGMEPP_VERSION >= 0x10E01 // 1.14.1
 # define GPGME_USERID_SIGNATURES_ARE_SORTABLE
 #endif
 
 using namespace GpgME;
 using namespace Kleo;
 
 class UIDModelItem
 {
     // A uid model item can either be a UserID::Signature or a UserID.
     // you can find out which it is if the uid or the signature return
     // null values. (Not null but isNull)
     //
 public:
     explicit UIDModelItem(const UserID::Signature &sig, UIDModelItem *parentItem, bool showRemarks)
         : mParentItem{parentItem}
         , mSig{sig}
     {
         mItemData  << QString::fromUtf8(sig.signerKeyID())
                    << Formatting::prettyName(sig)
                    << Formatting::prettyEMail(sig)
                    << Formatting::creationDateString(sig)
                    << Formatting::expirationDateString(sig)
                    << Formatting::validityShort(sig)
                    << (sig.isExportable() ? QStringLiteral("✓") : QString());
 
         QString lastNotation;
         if (showRemarks && parentItem) {
             for (const auto &notation: sig.notations()) {
                 if (notation.name() && !strcmp(notation.name(), "rem@gnupg.org")) {
                     lastNotation = QString::fromUtf8(notation.value());
                 }
             }
         }
         mItemData << lastNotation;
+
+#ifdef GPGMEPP_SUPPORTS_TRUST_SIGNATURES
+        mItemData << Formatting::trustSignatureDomain(sig);
+#endif
     }
 
     explicit UIDModelItem(const UserID &uid, UIDModelItem *parentItem)
         : mParentItem{parentItem}
         , mUid{uid}
     {
         mItemData << Formatting::prettyUserID(uid);
     }
 
     // The root item
     UIDModelItem()
     {
         mItemData << i18n("ID")
                   << i18n("Name")
                   << i18n("E-Mail")
                   << i18n("Valid From")
                   << i18n("Valid Until")
                   << i18n("Status")
                   << i18n("Exportable")
                   << i18n("Tags");
+#ifdef GPGMEPP_SUPPORTS_TRUST_SIGNATURES
+        mItemData << i18n("Trust Signature For");
+#endif
     }
 
     ~UIDModelItem()
     {
         qDeleteAll(mChildItems);
     }
 
     void appendChild(UIDModelItem *child)
     {
         mChildItems << child;
     }
 
     UIDModelItem *child(int row) const
     {
         return mChildItems.value(row);
     }
 
     const UIDModelItem *constChild(int row) const
     {
         return mChildItems.value(row);
     }
 
     int childCount() const
     {
         return mChildItems.count();
     }
 
     int columnCount() const
     {
         if (childCount()) {
             // We take the value from the first child
             // as we are likely a UID and our children
             // are UID Signatures.
             return constChild(0)->columnCount();
         }
         return mItemData.count();
     }
 
     QVariant data(int column) const
     {
         return mItemData.value(column);
     }
 
     QVariant toolTip(int column) const
     {
         if (!mSig.isNull()) {
             if (column == static_cast<int>(UserIDListModel::Column::Status)) {
                 return i18n("class %1", mSig.certClass());
+            } else if (column == static_cast<int>(UserIDListModel::Column::TrustSignatureDomain)) {
+                return Formatting::trustSignature(mSig);
             }
         }
         return mItemData.value(column);
     }
 
     QVariant icon(int column) const
     {
         if (!mSig.isNull() && column == static_cast<int>(UserIDListModel::Column::Status)) {
             return Formatting::validityIcon(mSig);
         }
         return {};
     }
 
     int row() const
     {
         if (mParentItem) {
             return mParentItem->mChildItems.indexOf(const_cast<UIDModelItem*>(this));
         }
         return 0;
     }
 
     UIDModelItem *parentItem() const
     {
         return mParentItem;
     }
 
     UserID::Signature signature() const
     {
         return mSig;
     }
 
     UserID uid() const
     {
         return mUid;
     }
 
 private:
     QList<UIDModelItem*> mChildItems;
     QList<QVariant> mItemData;
     UIDModelItem *mParentItem = nullptr;
     UserID::Signature mSig;
     UserID mUid;
 };
 
 UserIDListModel::UserIDListModel(QObject *p)
     : QAbstractItemModel{p}
 {
 }
 
 UserIDListModel::~UserIDListModel() = default;
 
 Key UserIDListModel::key() const
 {
     return mKey;
 }
 
 void UserIDListModel::setKey(const Key &key)
 {
     beginResetModel();
     mKey = key;
 
     mRootItem.reset(new UIDModelItem);
     for (int i = 0, ids = key.numUserIDs(); i < ids; ++i) {
         UserID uid = key.userID(i);
         auto uidItem = new UIDModelItem(uid, mRootItem.get());
         mRootItem->appendChild(uidItem);
         std::vector<UserID::Signature> sigs = uid.signatures();
 #ifdef GPGME_USERID_SIGNATURES_ARE_SORTABLE
         std::sort(sigs.begin(), sigs.end());
 #endif
         for (const auto &sig : sigs) {
             auto sigItem = new UIDModelItem(sig, uidItem, mRemarksEnabled);
             uidItem->appendChild(sigItem);
         }
     }
 
     endResetModel();
 }
 
 int UserIDListModel::columnCount(const QModelIndex &parent) const
 {
     if (parent.isValid()) {
         return static_cast<UIDModelItem*>(parent.internalPointer())->columnCount();
     }
 
     if (!mRootItem) {
         return 0;
     }
 
     return mRootItem->columnCount();
 }
 
 int UserIDListModel::rowCount(const QModelIndex &parent) const
 {
     if (parent.column() > 0 || !mRootItem) {
         return 0;
     }
 
     const UIDModelItem *const parentItem = !parent.isValid() ? mRootItem.get() : static_cast<UIDModelItem*>(parent.internalPointer());
     return parentItem->childCount();
 }
 
 QModelIndex UserIDListModel::index(int row, int column, const QModelIndex &parent) const
 {
     if (!hasIndex(row, column, parent)) {
         return {};
     }
 
     const UIDModelItem *const parentItem = !parent.isValid() ? mRootItem.get() : static_cast<UIDModelItem*>(parent.internalPointer());
     UIDModelItem *const childItem = parentItem->child(row);
     if (childItem) {
         return createIndex(row, column, childItem);
     } else {
         return QModelIndex();
     }
 }
 
 QModelIndex UserIDListModel::parent(const QModelIndex &index) const
 {
     if (!index.isValid()) {
         return {};
     }
     auto childItem = static_cast<UIDModelItem*>(index.internalPointer());
     UIDModelItem *parentItem = childItem->parentItem();
 
     if (parentItem == mRootItem.get()) {
         return QModelIndex();
     }
 
     return createIndex(parentItem->row(), 0, parentItem);
 }
 
 QVariant UserIDListModel::headerData(int section, Qt::Orientation o, int role) const
 {
     if (o == Qt::Horizontal && mRootItem) {
         if (role == Qt::DisplayRole || role == Qt::EditRole || role == Qt::ToolTipRole) {
             return mRootItem->data(section);
         }
     }
     return QVariant();
 }
 
 QVariant UserIDListModel::data(const QModelIndex &index, int role) const
 {
     if (!index.isValid()) {
         return QVariant();
     }
 
     if (role != Qt::DisplayRole && role != Qt::EditRole && role != Qt::ToolTipRole &&
         role != Qt::DecorationRole) {
         return QVariant();
     }
 
     auto item = static_cast<UIDModelItem*>(index.internalPointer());
 
     if (role == Qt::ToolTipRole) {
         return item->toolTip(index.column());
     }
 
     if (role == Qt::DecorationRole) {
         return item->icon(index.column());
     }
 
     return item->data(index.column());
 }
 
 UserID UserIDListModel::userID(const QModelIndex& index) const
 {
     if (!index.isValid()) {
         return UserID();
     }
     UIDModelItem *item = static_cast<UIDModelItem*>(index.internalPointer());
     return item->uid();
 }
 
 QVector<UserID> UserIDListModel::userIDs(const QModelIndexList &indexs) const
 {
     QVector<GpgME::UserID> ret;
     for (const QModelIndex &idx : indexs) {
         if (!idx.isValid()) {
             continue;
         }
         auto item = static_cast<UIDModelItem*>(idx.internalPointer());
         if (!item->uid().isNull()) {
             ret << item->uid();
         }
     }
     return ret;
 }
 
 UserID::Signature UserIDListModel::signature(const QModelIndex& index) const
 {
     if (!index.isValid()) {
         return UserID::Signature();
     }
     UIDModelItem *item = static_cast<UIDModelItem*>(index.internalPointer());
     return item->signature();
 }
 
 QVector<UserID::Signature> UserIDListModel::signatures(const QModelIndexList &indexs) const
 {
     QVector<GpgME::UserID::Signature> ret;
     for (const QModelIndex &idx : indexs) {
         if (!idx.isValid()) {
             continue;
         }
         auto item = static_cast<UIDModelItem*>(idx.internalPointer());
         if (!item->signature().isNull()) {
             ret << item->signature();
         }
     }
     return ret;
 }
 
 void UserIDListModel::enableRemarks(bool value)
 {
     mRemarksEnabled = value;
 }
diff --git a/src/models/useridlistmodel.h b/src/models/useridlistmodel.h
index 0a01c9aac..ca4fc5d29 100644
--- a/src/models/useridlistmodel.h
+++ b/src/models/useridlistmodel.h
@@ -1,72 +1,75 @@
 /* -*- mode: c++; c-basic-offset:4 -*-
     models/useridlistmodel.h
 
     This file is part of Kleopatra, the KDE keymanager
     SPDX-FileCopyrightText: 2007 Klarälvdalens Datakonsult AB
     SPDX-FileCopyrightText: 2016 Andre Heinecke <aheinecke@gnupg.org>
+    SPDX-FileCopyrightText: 2021 g10 Code GmbH
+    SPDX-FileContributor: Ingo Klöcker <dev@ingo-kloecker.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #pragma once
 
 #include <kleo_export.h>
 
 #include <QAbstractItemModel>
 
 #include <gpgme++/key.h> // since Signature is nested in UserID...
 
 #include <memory>
 
 class UIDModelItem;
 
 namespace Kleo
 {
 
 class KLEO_EXPORT UserIDListModel : public QAbstractItemModel
 {
     Q_OBJECT
 public:
     enum class Column {
         Id,
         Name,
         Email,
         ValidFrom,
         ValidUntil,
         Status,
         Exportable,
         Tags,
+        TrustSignatureDomain,
     };
 
     explicit UserIDListModel(QObject *parent = nullptr);
     ~UserIDListModel() override;
 
     GpgME::Key key() const;
 
 public:
     GpgME::UserID userID(const QModelIndex &index) const;
     QVector<GpgME::UserID> userIDs(const QModelIndexList &indexs) const;
     GpgME::UserID::Signature signature(const QModelIndex &index) const;
     QVector<GpgME::UserID::Signature> signatures(const QModelIndexList &indexs) const;
     void enableRemarks(bool value);
 
 public Q_SLOTS:
     void setKey(const GpgME::Key &key);
 
 public:
     int columnCount(const QModelIndex &pindex = QModelIndex()) const override;
     int rowCount(const QModelIndex &pindex = QModelIndex()) const override;
     QVariant headerData(int section, Qt::Orientation o, int role = Qt::DisplayRole) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
 
     QModelIndex index(int row, int col, const QModelIndex &parent = QModelIndex()) const override;
     QModelIndex parent(const QModelIndex &index) const override;
 
 private:
     GpgME::Key mKey;
     bool mRemarksEnabled = false;
     std::unique_ptr<UIDModelItem> mRootItem;
 };
 
 }
 
diff --git a/src/utils/formatting.cpp b/src/utils/formatting.cpp
index 8a6b9b0c2..8b18b586a 100644
--- a/src/utils/formatting.cpp
+++ b/src/utils/formatting.cpp
@@ -1,1205 +1,1252 @@
 /* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil; -*-
-
     utils/formatting.cpp
 
     This file is part of Kleopatra, the KDE keymanager
     SPDX-FileCopyrightText: 2007 Klarälvdalens Datakonsult AB
+    SPDX-FileCopyrightText: 2021 g10 Code GmbH
+    SPDX-FileContributor: Ingo Klöcker <dev@ingo-kloecker.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
+#include <config-libkleo.h>
+
 #include "formatting.h"
 #include "kleo/dn.h"
 #include "kleo/keyfiltermanager.h"
 #include "kleo/keygroup.h"
 
 #include "utils/cryptoconfig.h"
 
 #include <gpgme++/key.h>
 #include <gpgme++/importresult.h>
 
 #include <QGpgME/CryptoConfig>
 #include <QGpgME/Protocol>
 
 #include <KLocalizedString>
 #include <KEmailAddress>
 
 #include <QString>
 #include <QStringList>
 #include <QDateTime>
 #include <QTextDocument> // for Qt::escape
 #include <QLocale>
 #include <QIcon>
 #include <QRegularExpression>
 
 #include "models/keycache.h"
 
 using namespace GpgME;
 using namespace Kleo;
 
 //
 // Name
 //
 
 QString Formatting::prettyName(int proto, const char *id, const char *name_, const char *comment_)
 {
 
     if (proto == OpenPGP) {
         const QString name = QString::fromUtf8(name_);
         if (name.isEmpty()) {
             return QString();
         }
         const QString comment = QString::fromUtf8(comment_);
         if (comment.isEmpty()) {
             return name;
         }
         return QStringLiteral("%1 (%2)").arg(name, comment);
     }
 
     if (proto == CMS) {
         const DN subject(id);
         const QString cn = subject[QStringLiteral("CN")].trimmed();
         if (cn.isEmpty()) {
             return subject.prettyDN();
         }
         return cn;
     }
 
     return QString();
 }
 
 QString Formatting::prettyNameAndEMail(int proto, const char *id, const char *name_, const char *email_, const char *comment_)
 {
     return prettyNameAndEMail(proto, QString::fromUtf8(id), QString::fromUtf8(name_), prettyEMail(email_, id), QString::fromUtf8(comment_));
 }
 
 QString Formatting::prettyNameAndEMail(int proto, const QString &id, const QString &name, const QString &email, const QString &comment)
 {
 
     if (proto == OpenPGP) {
         if (name.isEmpty()) {
             if (email.isEmpty()) {
                 return QString();
             } else if (comment.isEmpty()) {
                 return QStringLiteral("<%1>").arg(email);
             } else {
                 return QStringLiteral("(%2) <%1>").arg(email, comment);
             }
         }
         if (email.isEmpty()) {
             if (comment.isEmpty()) {
                 return name;
             } else {
                 return QStringLiteral("%1 (%2)").arg(name, comment);
             }
         }
         if (comment.isEmpty()) {
             return QStringLiteral("%1 <%2>").arg(name, email);
         } else {
             return QStringLiteral("%1 (%3) <%2>").arg(name, email, comment);
         }
     }
 
     if (proto == CMS) {
         const DN subject(id);
         const QString cn = subject[QStringLiteral("CN")].trimmed();
         if (cn.isEmpty()) {
             return subject.prettyDN();
         }
         return cn;
     }
     return QString();
 }
 
 QString Formatting::prettyUserID(const UserID &uid)
 {
     if (uid.parent().protocol() == OpenPGP) {
         return prettyNameAndEMail(uid);
     }
     const QByteArray id = QByteArray(uid.id()).trimmed();
     if (id.startsWith('<')) {
         return prettyEMail(uid.email(), uid.id());
     }
     if (id.startsWith('('))
         // ### parse uri/dns:
     {
         return QString::fromUtf8(uid.id());
     } else {
         return DN(uid.id()).prettyDN();
     }
 }
 
 QString Formatting::prettyKeyID(const char *id)
 {
     if (!id) {
         return QString();
     }
     return QLatin1String("0x") + QString::fromLatin1(id).toUpper();
 }
 
 QString Formatting::prettyNameAndEMail(const UserID &uid)
 {
     return prettyNameAndEMail(uid.parent().protocol(), uid.id(), uid.name(), uid.email(), uid.comment());
 }
 
 QString Formatting::prettyNameAndEMail(const Key &key)
 {
     return prettyNameAndEMail(key.userID(0));
 }
 
 QString Formatting::prettyName(const Key &key)
 {
     return prettyName(key.userID(0));
 }
 
 QString Formatting::prettyName(const UserID &uid)
 {
     return prettyName(uid.parent().protocol(), uid.id(), uid.name(), uid.comment());
 }
 
 QString Formatting::prettyName(const UserID::Signature &sig)
 {
     return prettyName(OpenPGP, sig.signerUserID(), sig.signerName(), sig.signerComment());
 }
 
 //
 // EMail
 //
 
 QString Formatting::prettyEMail(const Key &key)
 {
     for (unsigned int i = 0, end = key.numUserIDs(); i < end; ++i) {
         const QString email = prettyEMail(key.userID(i));
         if (!email.isEmpty()) {
             return email;
         }
     }
     return QString();
 }
 
 QString Formatting::prettyEMail(const UserID &uid)
 {
     return prettyEMail(uid.email(), uid.id());
 }
 
 QString Formatting::prettyEMail(const UserID::Signature &sig)
 {
     return prettyEMail(sig.signerEmail(), sig.signerUserID());
 }
 
 QString Formatting::prettyEMail(const char *email_, const char *id)
 {
     QString email, name, comment;
     if (email_ && KEmailAddress::splitAddress(QString::fromUtf8(email_),
                                               name, email, comment) == KEmailAddress::AddressOk) {
         return email;
     } else {
         return DN(id)[QStringLiteral("EMAIL")].trimmed();
     }
 }
 
 //
 // Tooltip
 //
 
 namespace
 {
 
 static QString protect_whitespace(QString s)
 {
     static const QLatin1Char SP(' '), NBSP('\xA0');
     return s.replace(SP, NBSP);
 }
 
 template <typename T_arg>
 QString format_row(const QString &field, const T_arg &arg)
 {
     return QStringLiteral("<tr><th>%1:</th><td>%2</td></tr>").arg(protect_whitespace(field), arg);
 }
 QString format_row(const QString &field, const QString &arg)
 {
     return QStringLiteral("<tr><th>%1:</th><td>%2</td></tr>").arg(protect_whitespace(field), arg.toHtmlEscaped());
 }
 QString format_row(const QString &field, const char *arg)
 {
     return format_row(field, QString::fromUtf8(arg));
 }
 
 QString format_keytype(const Key &key)
 {
     const Subkey subkey = key.subkey(0);
     if (key.hasSecret()) {
         return i18n("%1-bit %2 (secret key available)", subkey.length(), QLatin1String(subkey.publicKeyAlgorithmAsString()));
     } else {
         return i18n("%1-bit %2", subkey.length(), QLatin1String(subkey.publicKeyAlgorithmAsString()));
     }
 }
 
 QString format_subkeytype(const Subkey &subkey)
 {
     const auto algo = subkey.publicKeyAlgorithm();
 
     if (algo == Subkey::AlgoECC ||
         algo == Subkey::AlgoECDSA ||
         algo == Subkey::AlgoECDH ||
         algo == Subkey::AlgoEDDSA) {
         return QString::fromStdString(subkey.algoName());
     }
     return i18n("%1-bit %2", subkey.length(), QLatin1String(subkey.publicKeyAlgorithmAsString()));
 }
 
 QString format_keyusage(const Key &key)
 {
     QStringList capabilities;
     if (key.canReallySign()) {
         if (key.isQualified()) {
             capabilities.push_back(i18n("Signing (Qualified)"));
         } else {
             capabilities.push_back(i18n("Signing"));
         }
     }
     if (key.canEncrypt()) {
         capabilities.push_back(i18n("Encryption"));
     }
     if (key.canCertify()) {
         capabilities.push_back(i18n("Certifying User-IDs"));
     }
     if (key.canAuthenticate()) {
         capabilities.push_back(i18n("SSH Authentication"));
     }
     return capabilities.join(QLatin1String(", "));
 }
 
 QString format_subkeyusage(const Subkey &subkey)
 {
     QStringList capabilities;
     if (subkey.canSign()) {
         if (subkey.isQualified()) {
             capabilities.push_back(i18n("Signing (Qualified)"));
         } else {
             capabilities.push_back(i18n("Signing"));
         }
     }
     if (subkey.canEncrypt()) {
         capabilities.push_back(i18n("Encryption"));
     }
     if (subkey.canCertify()) {
         capabilities.push_back(i18n("Certifying User-IDs"));
     }
     if (subkey.canAuthenticate()) {
         capabilities.push_back(i18n("SSH Authentication"));
     }
     return capabilities.join(QLatin1String(", "));
 }
 
 static QString time_t2string(time_t t)
 {
     QDateTime dt;
     dt.setTime_t(t);
     return QLocale().toString(dt, QLocale::ShortFormat);
 }
 
 static QString make_red(const QString &txt)
 {
     return QLatin1String("<font color=\"red\">") + txt.toHtmlEscaped() + QLatin1String("</font>");
 }
 
 }
 
 QString Formatting::toolTip(const Key &key, int flags)
 {
     if (flags == 0 || (key.protocol() != CMS && key.protocol() != OpenPGP)) {
         return QString();
     }
 
     const Subkey subkey = key.subkey(0);
 
     QString result;
     if (flags & Validity) {
         if (key.protocol() == OpenPGP || (key.keyListMode() & Validate)) {
             if (key.isRevoked()) {
                 result = make_red(i18n("Revoked"));
             } else if (key.isExpired()) {
                 result = make_red(i18n("Expired"));
             } else if (key.isDisabled()) {
                 result = i18n("Disabled");
             } else if (key.keyListMode() & GpgME::Validate) {
                 unsigned int fullyTrusted = 0;
                 for (const auto &uid: key.userIDs()) {
                     if (uid.validity() >= UserID::Validity::Full) {
                         fullyTrusted++;
                     }
                 }
                 if (fullyTrusted == key.numUserIDs()) {
                     result = i18n("All User-IDs are certified.");
                     const auto compliance = complianceStringForKey(key);
                     if (!compliance.isEmpty()) {
                         result += QStringLiteral("<br>") + compliance;
                     }
                 } else {
                     result = i18np("One User-ID is not certified.", "%1 User-IDs are not certified.", key.numUserIDs() - fullyTrusted);
                 }
             } else {
                 result = i18n("The validity cannot be checked at the moment.");
             }
         } else {
             result = i18n("The validity cannot be checked at the moment.");
         }
     }
     if (flags == Validity) {
         return result;
     }
 
     result += QLatin1String("<table border=\"0\">");
     if (key.protocol() == CMS) {
         if (flags & SerialNumber) {
             result += format_row(i18n("Serial number"), key.issuerSerial());
         }
         if (flags & Issuer) {
             result += format_row(i18n("Issuer"), key.issuerName());
         }
     }
     if (flags & UserIDs) {
         const std::vector<UserID> uids = key.userIDs();
         if (!uids.empty())
             result += format_row(key.protocol() == CMS
                                  ? i18n("Subject")
                                  : i18n("User-ID"), prettyUserID(uids.front()));
         if (uids.size() > 1)
             for (auto it = uids.begin() + 1, end = uids.end(); it != end; ++it)
                 if (!it->isRevoked() && !it->isInvalid()) {
                     result += format_row(i18n("a.k.a."), prettyUserID(*it));
                 }
     }
     if (flags & ExpiryDates) {
         result += format_row(i18n("Created"), time_t2string(subkey.creationTime()));
 
         if (key.isExpired()) {
             result += format_row(i18n("Expired"), time_t2string(subkey.expirationTime()));
         } else if (!subkey.neverExpires()) {
             result += format_row(i18n("Expires"), time_t2string(subkey.expirationTime()));
         }
     }
     if (flags & CertificateType) {
         result += format_row(i18n("Type"), format_keytype(key));
     }
     if (flags & CertificateUsage) {
         result += format_row(i18n("Usage"), format_keyusage(key));
     }
     if (flags & KeyID) {
         result += format_row(i18n("Key-ID"), QString::fromLatin1(key.shortKeyID()));
     }
     if (flags & Fingerprint) {
         result += format_row(i18n("Fingerprint"), key.primaryFingerprint());
     }
     if (flags & OwnerTrust) {
         if (key.protocol() == OpenPGP) {
             result += format_row(i18n("Certification trust"), ownerTrustShort(key));
         } else if (key.isRoot()) {
             result += format_row(i18n("Trusted issuer?"),
                                  key.userID(0).validity() == UserID::Ultimate ? i18n("Yes") :
                                  /* else */                                     i18n("No"));
         }
     }
 
     if (flags & StorageLocation) {
         if (const char *card = subkey.cardSerialNumber()) {
             result += format_row(i18n("Stored"), i18nc("stored...", "on SmartCard with serial no. %1", QString::fromUtf8(card)));
         } else {
             result += format_row(i18n("Stored"), i18nc("stored...", "on this computer"));
         }
     }
     if (flags & Subkeys) {
         for (const auto &sub: key.subkeys()) {
             result += QLatin1String("<hr/>");
             result += format_row(i18n("Subkey"), sub.fingerprint());
             if (sub.isRevoked()) {
                 result += format_row(i18n("Status"), i18n("Revoked"));
             } else if (sub.isExpired()) {
                 result += format_row(i18n("Status"), i18n("Expired"));
             }
             if (flags & ExpiryDates) {
                 result += format_row(i18n("Created"), time_t2string(sub.creationTime()));
 
                 if (key.isExpired()) {
                     result += format_row(i18n("Expired"), time_t2string(sub.expirationTime()));
                 } else if (!subkey.neverExpires()) {
                     result += format_row(i18n("Expires"), time_t2string(sub.expirationTime()));
                 }
             }
 
             if (flags & CertificateType) {
                 result += format_row(i18n("Type"), format_subkeytype(sub));
             }
             if (flags & CertificateUsage) {
                 result += format_row(i18n("Usage"), format_subkeyusage(sub));
             }
             if (flags & StorageLocation) {
                 if (const char *card = sub.cardSerialNumber()) {
                     result += format_row(i18n("Stored"), i18nc("stored...", "on SmartCard with serial no. %1", QString::fromUtf8(card)));
                 } else {
                     result += format_row(i18n("Stored"), i18nc("stored...", "on this computer"));
                 }
             }
         }
     }
     result += QLatin1String("</table>");
 
     return result;
 }
 
 namespace
 {
 template <typename Container>
 QString getValidityStatement(const Container &keys)
 {
     const bool allKeysAreOpenPGP = std::all_of(keys.cbegin(), keys.cend(), [] (const Key &key) { return key.protocol() == OpenPGP; });
     const bool allKeysAreValidated = std::all_of(keys.cbegin(), keys.cend(), [] (const Key &key) { return key.keyListMode() & Validate; });
     if (allKeysAreOpenPGP || allKeysAreValidated) {
         const bool someKeysAreBad = std::any_of(keys.cbegin(), keys.cend(), std::mem_fn(&Key::isBad));
         if (someKeysAreBad) {
             return i18n("Some keys are revoked, expired, disabled, or invalid.");
         } else {
             const bool allKeysAreFullyValid = std::all_of(keys.cbegin(), keys.cend(), &Formatting::uidsHaveFullValidity);
             if (allKeysAreFullyValid) {
                 return i18n("All keys are certified.");
             } else {
                 return i18n("Some keys are not certified.");
             }
         }
     }
     return i18n("The validity of the keys cannot be checked at the moment.");
 }
 }
 
 QString Formatting::toolTip(const KeyGroup &group, int flags)
 {
     static const unsigned int maxNumKeysForTooltip = 20;
 
     if (group.isNull()) {
         return QString();
     }
 
     const KeyGroup::Keys &keys = group.keys();
     if (keys.size() == 0) {
         return i18nc("@info:tooltip", "This group does not contain any keys.");
     }
 
     const QString validity = (flags & Validity) ? getValidityStatement(keys) : QString();
     if (flags == Validity) {
         return validity;
     }
 
     // list either up to maxNumKeysForTooltip keys or (maxNumKeysForTooltip-1) keys followed by "and n more keys"
     const unsigned int numKeysForTooltip = keys.size() > maxNumKeysForTooltip ? maxNumKeysForTooltip - 1 : keys.size();
 
     QStringList result;
     result.reserve(3 + 2 + numKeysForTooltip + 2);
     if (!validity.isEmpty()) {
         result.push_back(QStringLiteral("<p>"));
         result.push_back(validity.toHtmlEscaped());
         result.push_back(QStringLiteral("</p>"));
     }
 
     result.push_back(QStringLiteral("<p>"));
     result.push_back(i18n("Keys:"));
     {
         auto it = keys.cbegin();
         for (unsigned int i = 0; i < numKeysForTooltip; ++i, ++it) {
             result.push_back(QLatin1String("<br>") + Formatting::summaryLine(*it).toHtmlEscaped());
         }
     }
     if (keys.size() > numKeysForTooltip) {
         result.push_back(QLatin1String("<br>") + i18ncp("this follows a list of keys", "and 1 more key", "and %1 more keys", keys.size() - numKeysForTooltip));
     }
     result.push_back(QStringLiteral("</p>"));
 
     return result.join(QLatin1Char('\n'));
 }
 
 //
 // Creation and Expiration
 //
 
 namespace
 {
 static QDate time_t2date(time_t t)
 {
     if (!t) {
         return {};
     }
     QDateTime dt;
     dt.setTime_t(t);
     return dt.date();
 }
 static QString date2string(const QDate &date)
 {
     return QLocale().toString(date, QLocale::ShortFormat);
 }
 
 template <typename T>
 QString expiration_date_string(const T &tee)
 {
     return tee.neverExpires() ? QString() : date2string(time_t2date(tee.expirationTime()));
 }
 template <typename T>
 QDate creation_date(const T &tee)
 {
     return time_t2date(tee.creationTime());
 }
 template <typename T>
 QDate expiration_date(const T &tee)
 {
     return time_t2date(tee.expirationTime());
 }
 }
 
 QString Formatting::dateString(time_t t)
 {
     return date2string(time_t2date(t));
 }
 
 QString Formatting::expirationDateString(const Key &key)
 {
     return expiration_date_string(key.subkey(0));
 }
 
 QString Formatting::expirationDateString(const Subkey &subkey)
 {
     return expiration_date_string(subkey);
 }
 
 QString Formatting::expirationDateString(const UserID::Signature &sig)
 {
     return expiration_date_string(sig);
 }
 
 QDate Formatting::expirationDate(const Key &key)
 {
     return expiration_date(key.subkey(0));
 }
 
 QDate Formatting::expirationDate(const Subkey &subkey)
 {
     return expiration_date(subkey);
 }
 
 QDate Formatting::expirationDate(const UserID::Signature &sig)
 {
     return expiration_date(sig);
 }
 
 QString Formatting::creationDateString(const Key &key)
 {
     return date2string(creation_date(key.subkey(0)));
 }
 
 QString Formatting::creationDateString(const Subkey &subkey)
 {
     return date2string(creation_date(subkey));
 }
 
 QString Formatting::creationDateString(const UserID::Signature &sig)
 {
     return date2string(creation_date(sig));
 }
 
 QDate Formatting::creationDate(const Key &key)
 {
     return creation_date(key.subkey(0));
 }
 
 QDate Formatting::creationDate(const Subkey &subkey)
 {
     return creation_date(subkey);
 }
 
 QDate Formatting::creationDate(const UserID::Signature &sig)
 {
     return creation_date(sig);
 }
 
 //
 // Types
 //
 
 QString Formatting::displayName(Protocol p)
 {
     if (p == CMS) {
         return i18nc("X.509/CMS encryption standard", "S/MIME");
     }
     if (p == OpenPGP) {
         return i18n("OpenPGP");
     }
     return i18nc("Unknown encryption protocol", "Unknown");
 }
 
 QString Formatting::type(const Key &key)
 {
     return displayName(key.protocol());
 }
 
 QString Formatting::type(const Subkey &subkey)
 {
     return QString::fromUtf8(subkey.publicKeyAlgorithmAsString());
 }
 
 QString Formatting::type(const KeyGroup &group)
 {
     Q_UNUSED(group)
     return i18nc("a group of keys/certificates", "Group");
 }
 
 //
 // Status / Validity
 //
 
 QString Formatting::ownerTrustShort(const Key &key)
 {
     return ownerTrustShort(key.ownerTrust());
 }
 
 QString Formatting::ownerTrustShort(Key::OwnerTrust trust)
 {
     switch (trust) {
     case Key::Unknown:   return i18nc("unknown trust level", "unknown");
     case Key::Never:     return i18n("untrusted");
     case Key::Marginal:  return i18nc("marginal trust", "marginal");
     case Key::Full:      return i18nc("full trust", "full");
     case Key::Ultimate:  return i18nc("ultimate trust", "ultimate");
     case Key::Undefined: return i18nc("undefined trust", "undefined");
     default:
         Q_ASSERT(!"unexpected owner trust value");
         break;
     }
     return QString();
 }
 
 QString Formatting::validityShort(const Subkey &subkey)
 {
     if (subkey.isRevoked()) {
         return i18n("revoked");
     }
     if (subkey.isExpired()) {
         return i18n("expired");
     }
     if (subkey.isDisabled()) {
         return i18n("disabled");
     }
     if (subkey.isInvalid()) {
         return i18n("invalid");
     }
     return i18nc("as in good/valid signature", "good");
 }
 
 QString Formatting::validityShort(const UserID &uid)
 {
     if (uid.isRevoked()) {
         return i18n("revoked");
     }
     if (uid.isInvalid()) {
         return i18n("invalid");
     }
     switch (uid.validity()) {
     case UserID::Unknown:   return i18nc("unknown trust level", "unknown");
     case UserID::Undefined: return i18nc("undefined trust", "undefined");
     case UserID::Never:     return i18n("untrusted");
     case UserID::Marginal:  return i18nc("marginal trust", "marginal");
     case UserID::Full:      return i18nc("full trust", "full");
     case UserID::Ultimate:  return i18nc("ultimate trust", "ultimate");
     }
     return QString();
 }
 
 QString Formatting::validityShort(const UserID::Signature &sig)
 {
     switch (sig.status()) {
     case UserID::Signature::NoError:
         if (!sig.isInvalid()) {
             /* See RFC 4880 Section 5.2.1 */
             switch (sig.certClass()) {
             case 0x10: /* Generic */
             case 0x11: /* Persona */
             case 0x12: /* Casual */
             case 0x13: /* Positive */
                 return i18n("valid");
             case 0x30:
                 return i18n("revoked");
             default:
                 return i18n("class %1", sig.certClass());
             }
         }
         Q_FALLTHROUGH();
         // fall through:
     case UserID::Signature::GeneralError:
         return i18n("invalid");
     case UserID::Signature::SigExpired:   return i18n("expired");
     case UserID::Signature::KeyExpired:   return i18n("certificate expired");
     case UserID::Signature::BadSignature: return i18nc("fake/invalid signature", "bad");
     case UserID::Signature::NoPublicKey: {
             /* GnuPG returns the same error for no public key as for expired
              * or revoked certificates. */
             const auto key = KeyCache::instance()->findByKeyIDOrFingerprint (sig.signerKeyID());
             if (key.isNull()) {
                 return i18n("no public key");
             } else if (key.isExpired()) {
                 return i18n("key expired");
             } else if (key.isRevoked()) {
                 return i18n("key revoked");
             } else if (key.isDisabled()) {
                 return i18n("key disabled");
             }
             /* can't happen */
             return QStringLiteral("unknown");
         }
     }
     return QString();
 }
 
 QIcon Formatting::validityIcon(const UserID::Signature &sig)
 {
     switch (sig.status()) {
     case UserID::Signature::NoError:
         if (!sig.isInvalid()) {
             /* See RFC 4880 Section 5.2.1 */
             switch (sig.certClass()) {
             case 0x10: /* Generic */
             case 0x11: /* Persona */
             case 0x12: /* Casual */
             case 0x13: /* Positive */
                 return QIcon::fromTheme(QStringLiteral("emblem-success"));
             case 0x30:
                 return QIcon::fromTheme(QStringLiteral("emblem-error"));
             default:
                 return QIcon();
             }
         }
         Q_FALLTHROUGH();
         // fall through:
     case UserID::Signature::BadSignature:
     case UserID::Signature::GeneralError:
         return QIcon::fromTheme(QStringLiteral("emblem-error"));
     case UserID::Signature::SigExpired:
     case UserID::Signature::KeyExpired:
         return QIcon::fromTheme(QStringLiteral("emblem-information"));
     case UserID::Signature::NoPublicKey:
         return QIcon::fromTheme(QStringLiteral("emblem-question"));
     }
     return QIcon();
 }
 
 QString Formatting::formatKeyLink(const Key &key)
 {
     if (key.isNull()) {
         return QString();
     }
     return QStringLiteral("<a href=\"key:%1\">%2</a>").arg(QLatin1String(key.primaryFingerprint()), Formatting::prettyName(key));
 }
 
 QString Formatting::formatForComboBox(const GpgME::Key &key)
 {
     const QString name = prettyName(key);
     QString mail = prettyEMail(key);
     if (!mail.isEmpty()) {
         mail = QLatin1Char('<') + mail + QLatin1Char('>');
     }
     return i18nc("name, email, key id", "%1 %2 (%3)", name, mail, QLatin1String(key.shortKeyID())).simplified();
 }
 
 namespace
 {
 
 static QString keyToString(const Key &key)
 {
 
     Q_ASSERT(!key.isNull());
 
     const QString email = Formatting::prettyEMail(key);
     const QString name = Formatting::prettyName(key);
 
     if (name.isEmpty()) {
         return email;
     } else if (email.isEmpty()) {
         return name;
     } else {
         return QStringLiteral("%1 <%2>").arg(name, email);
     }
 }
 
 }
 
 const char *Formatting::summaryToString(const Signature::Summary summary)
 {
     if (summary & Signature::Red) {
         return "RED";
     }
     if (summary & Signature::Green) {
         return "GREEN";
     }
     return "YELLOW";
 }
 
 QString Formatting::signatureToString(const Signature &sig, const Key &key)
 {
     if (sig.isNull()) {
         return QString();
     }
 
     const bool red   = (sig.summary() & Signature::Red);
     const bool valid = (sig.summary() & Signature::Valid);
 
     if (red)
         if (key.isNull())
             if (const char *fpr = sig.fingerprint()) {
                 return i18n("Bad signature by unknown certificate %1: %2", QString::fromLatin1(fpr), QString::fromLocal8Bit(sig.status().asString()));
             } else {
                 return i18n("Bad signature by an unknown certificate: %1", QString::fromLocal8Bit(sig.status().asString()));
             }
         else {
             return i18n("Bad signature by %1: %2", keyToString(key), QString::fromLocal8Bit(sig.status().asString()));
         }
 
     else if (valid)
         if (key.isNull())
             if (const char *fpr = sig.fingerprint()) {
                 return i18n("Good signature by unknown certificate %1.", QString::fromLatin1(fpr));
             } else {
                 return i18n("Good signature by an unknown certificate.");
             }
         else {
             return i18n("Good signature by %1.", keyToString(key));
         }
 
     else if (key.isNull())
         if (const char *fpr = sig.fingerprint()) {
             return i18n("Invalid signature by unknown certificate %1: %2", QString::fromLatin1(fpr), QString::fromLocal8Bit(sig.status().asString()));
         } else {
             return i18n("Invalid signature by an unknown certificate: %1", QString::fromLocal8Bit(sig.status().asString()));
         }
     else {
         return i18n("Invalid signature by %1: %2", keyToString(key), QString::fromLocal8Bit(sig.status().asString()));
     }
 }
 
 //
 // ImportResult
 //
 
 QString Formatting::importMetaData(const Import &import, const QStringList &ids)
 {
     const QString result = importMetaData(import);
     if (result.isEmpty()) {
         return QString();
     } else
         return result + QLatin1Char('\n') +
                i18n("This certificate was imported from the following sources:") + QLatin1Char('\n') +
                ids.join(QLatin1Char('\n'));
 }
 
 QString Formatting::importMetaData(const Import &import)
 {
 
     if (import.isNull()) {
         return QString();
     }
 
     if (import.error().isCanceled()) {
         return i18n("The import of this certificate was canceled.");
     }
     if (import.error())
         return i18n("An error occurred importing this certificate: %1",
                     QString::fromLocal8Bit(import.error().asString()));
 
     const unsigned int status = import.status();
     if (status & Import::NewKey)
         return (status & Import::ContainedSecretKey)
                ? i18n("This certificate was new to your keystore. The secret key is available.")
                : i18n("This certificate is new to your keystore.");
 
     QStringList results;
     if (status & Import::NewUserIDs) {
         results.push_back(i18n("New user-ids were added to this certificate by the import."));
     }
     if (status & Import::NewSignatures) {
         results.push_back(i18n("New signatures were added to this certificate by the import."));
     }
     if (status & Import::NewSubkeys) {
         results.push_back(i18n("New subkeys were added to this certificate by the import."));
     }
 
     return results.empty()
            ? i18n("The import contained no new data for this certificate. It is unchanged.")
            : results.join(QLatin1Char('\n'));
 }
 
 //
 // Overview in CertificateDetailsDialog
 //
 
 QString Formatting::formatOverview(const Key &key)
 {
     return toolTip(key, AllOptions);
 }
 
 QString Formatting::usageString(const Subkey &sub)
 {
     QStringList usageStrings;
     if (sub.canCertify()) {
         usageStrings << i18n("Certify");
     }
     if (sub.canSign()) {
         usageStrings << i18n("Sign");
     }
     if (sub.canEncrypt()) {
         usageStrings << i18n("Encrypt");
     }
     if (sub.canAuthenticate()) {
         usageStrings << i18n("Authenticate");
     }
     return usageStrings.join(QLatin1String(", "));
 }
 
 QString Formatting::summaryLine(const Key &key)
 {
     return keyToString(key) + QLatin1Char(' ') +
            i18nc("(validity, protocol, creation date)",
                  "(%1, %2, created: %3)",
 		 Formatting::complianceStringShort(key),
 		 displayName(key.protocol()),
                  Formatting::creationDateString(key));
 }
 
 QString Formatting::summaryLine(const KeyGroup &group)
 {
     switch (group.source()) {
         case KeyGroup::ApplicationConfig:
         case KeyGroup::GnuPGConfig:
             return i18ncp("name of group of keys (n key(s), validity)",
                           "%2 (1 key, %3)", "%2 (%1 keys, %3)",
                           group.keys().size(), group.name(), Formatting::complianceStringShort(group));
         case KeyGroup::Tags:
             return i18ncp("name of group of keys (n key(s), validity, tag)",
                           "%2 (1 key, %3, tag)", "%2 (%1 keys, %3, tag)",
                           group.keys().size(), group.name(), Formatting::complianceStringShort(group));
         default:
             return i18ncp("name of group of keys (n key(s), validity, group ...)",
                           "%2 (1 key, %3, unknown origin)", "%2 (%1 keys, %3, unknown origin)",
                           group.keys().size(), group.name(), Formatting::complianceStringShort(group));
     }
 }
 
 namespace
 {
 QIcon iconForValidity(UserID::Validity validity)
 {
     switch (validity) {
         case UserID::Ultimate:
         case UserID::Full:
         case UserID::Marginal:
             return QIcon::fromTheme(QStringLiteral("emblem-success"));
         case UserID::Never:
             return QIcon::fromTheme(QStringLiteral("emblem-error"));
         case UserID::Undefined:
         case UserID::Unknown:
         default:
             return QIcon::fromTheme(QStringLiteral("emblem-information"));
     }
 }
 }
 
 // Icon for certificate selection indication
 QIcon Formatting::iconForUid(const UserID &uid)
 {
     return iconForValidity(uid.validity());
 }
 
 QString Formatting::validity(const UserID &uid)
 {
     switch (uid.validity()) {
         case UserID::Ultimate:
             return i18n("The certificate is marked as your own.");
         case UserID::Full:
             return i18n("The certificate belongs to this recipient.");
         case UserID::Marginal:
             return i18n("The trust model indicates marginally that the certificate belongs to this recipient.");
         case UserID::Never:
             return i18n("This certificate should not be used.");
         case UserID::Undefined:
         case UserID::Unknown:
         default:
             return i18n("There is no indication that this certificate belongs to this recipient.");
     }
 }
 
 QString Formatting::validity(const KeyGroup &group)
 {
     if (group.isNull()) {
         return QString();
     }
 
     const KeyGroup::Keys &keys = group.keys();
     if (keys.size() == 0) {
         return i18n("This group does not contain any keys.");
     }
 
     return getValidityStatement(keys);
 }
 
 namespace
 {
 UserID::Validity minimalValidityOfNotRevokedUserIDs(const Key &key)
 {
     std::vector<UserID> userIDs = key.userIDs();
     const auto endOfNotRevokedUserIDs = std::remove_if(userIDs.begin(), userIDs.end(), std::mem_fn(&UserID::isRevoked));
     const int minValidity = std::accumulate(userIDs.begin(), endOfNotRevokedUserIDs, UserID::Ultimate + 1,
                                             [] (int validity, const UserID &userID) {
                                                 return std::min(validity, static_cast<int>(userID.validity()));
                                             });
     return minValidity <= UserID::Ultimate ? static_cast<UserID::Validity>(minValidity) : UserID::Unknown;
 }
 
 template <typename Container>
 UserID::Validity minimalValidity(const Container& keys)
 {
     const int minValidity = std::accumulate(keys.cbegin(), keys.cend(), UserID::Ultimate + 1,
                                             [] (int validity, const Key &key) {
                                                 return std::min<int>(validity, minimalValidityOfNotRevokedUserIDs(key));
                                             });
     return minValidity <= UserID::Ultimate ? static_cast<UserID::Validity>(minValidity) : UserID::Unknown;
 }
 }
 
 QIcon Formatting::validityIcon(const KeyGroup &group)
 {
     return iconForValidity(minimalValidity(group.keys()));
 }
 
 bool Formatting::uidsHaveFullValidity(const Key &key)
 {
     return minimalValidityOfNotRevokedUserIDs(key) >= UserID::Full;
 }
 
 QString Formatting::complianceMode()
 {
     const auto complianceValue = getCryptoConfigStringValue("gpg", "compliance");
     return complianceValue == QLatin1String("gnupg") ? QString() : complianceValue;
 }
 
 bool Formatting::isKeyDeVs(const GpgME::Key &key)
 {
     for (const auto &sub: key.subkeys()) {
         if (sub.isExpired() || sub.isRevoked()) {
             // Ignore old subkeys
             continue;
         }
         if (!sub.isDeVs()) {
             return false;
         }
     }
     return true;
 }
 
 QString Formatting::complianceStringForKey(const GpgME::Key &key)
 {
     // There will likely be more in the future for other institutions
     // for now we only have DE-VS
     if (complianceMode() == QLatin1String("de-vs")) {
         if (uidsHaveFullValidity(key) && isKeyDeVs(key)) {
             return i18nc("%1 is a placeholder for the name of a compliance mode. E.g. NATO RESTRICTED compliant or VS-NfD compliant",
                          "May be used for %1 communication.", deVsString());
         } else {
             return i18nc("VS-NfD-conforming is a German standard for restricted documents. For which special restrictions about algorithms apply. The string describes if a key is compliant to that..",
                          "May <b>not</b> be used for %1 communication.", deVsString());
         }
     }
     return QString();
 }
 
 QString Formatting::complianceStringShort(const GpgME::Key &key)
 {
     const bool keyValidityChecked = (key.keyListMode() & GpgME::Validate);
     if (keyValidityChecked && Formatting::uidsHaveFullValidity(key)) {
         if (complianceMode() == QLatin1String("de-vs")
             && Formatting::isKeyDeVs(key)) {
             return QStringLiteral("★ ") + deVsString(true);
         }
         return i18nc("As in all user IDs are valid.", "certified");
     }
     if (key.isExpired()) {
         return i18n("expired");
     }
     if (key.isRevoked()) {
         return i18n("revoked");
     }
     if (key.isDisabled()) {
         return i18n("disabled");
     }
     if (key.isInvalid()) {
         return i18n("invalid");
     }
     if (keyValidityChecked) {
         return i18nc("As in not all user IDs are valid.", "not certified");
     }
 
     return i18nc("The validity of the user IDs has not been/could not be checked", "not checked");
 }
 
 QString Formatting::complianceStringShort(const KeyGroup &group)
 {
     const KeyGroup::Keys &keys = group.keys();
 
     const bool allKeysFullyValid = std::all_of(keys.cbegin(), keys.cend(), &Formatting::uidsHaveFullValidity);
     if (allKeysFullyValid) {
         return i18nc("As in all keys are valid.", "all certified");
     }
 
     return i18nc("As in not all keys are valid.", "not all certified");
 }
 
 QString Formatting::prettyID(const char *id)
 {
     if (!id) {
         return QString();
     }
     QString ret = QString::fromLatin1(id).toUpper().replace(QRegularExpression(QStringLiteral("(....)")),
                                                             QStringLiteral("\\1 ")).trimmed();
     // For the standard 10 group fingerprint let us use a double space in the
     // middle to increase readability
     if (ret.size() == 49) {
         ret.insert(24, QLatin1Char(' '));
     }
     return ret;
 }
 
 QString Formatting::origin(int o)
 {
     switch (o) {
         case Key::OriginKS:
             return i18n("Keyserver");
         case Key::OriginDane:
             return QStringLiteral("DANE");
         case Key::OriginWKD:
             return QStringLiteral("WKD");
         case Key::OriginURL:
             return QStringLiteral("URL");
         case Key::OriginFile:
             return i18n("File import");
         case Key::OriginSelf:
             return i18n("Generated");
         case Key::OriginOther:
         case Key::OriginUnknown:
         default:
           return i18n("Unknown");
     }
 }
 
 QString Formatting::deVsString(bool compliant)
 {
     const auto filter = KeyFilterManager::instance()->keyFilterByID(compliant ?
             QStringLiteral("de-vs-filter") :
             QStringLiteral("not-de-vs-filter"));
     if (!filter) {
         return compliant ? i18n("VS-NfD compliant") : i18n("Not VS-NfD compliant");
     }
     return filter->name();
 }
+
+namespace
+{
+QString formatTrustScope(const char *trustScope)
+{
+    static const QRegularExpression escapedNonAlphaNum{QStringLiteral(R"(\\([^0-9A-Za-z]))")};
+
+    const auto scopeRegExp = QString::fromUtf8(trustScope);
+    if (scopeRegExp.startsWith(u"<[^>]+[@.]") && scopeRegExp.endsWith(u">$")) {
+        // looks like a trust scope regular expression created by gpg
+        auto domain = scopeRegExp.mid(10, scopeRegExp.size() - 10 - 2);
+        domain.replace(escapedNonAlphaNum, QStringLiteral(R"(\1)"));
+        return domain;
+    }
+    return scopeRegExp;
+}
+}
+
+QString Formatting::trustSignatureDomain(const GpgME::UserID::Signature &sig)
+{
+#ifdef GPGMEPP_SUPPORTS_TRUST_SIGNATURES
+    return formatTrustScope(sig.trustScope());
+#else
+    return {};
+#endif
+}
+
+QString Formatting::trustSignature(const GpgME::UserID::Signature &sig)
+{
+#ifdef GPGMEPP_SUPPORTS_TRUST_SIGNATURES
+    switch (sig.trustValue()) {
+    case TrustSignatureTrust::Partial:
+        return i18nc("Certifies this key as partially trusted introducer for 'domain name'.",
+                     "Certifies this key as partially trusted introducer for '%1'.", trustSignatureDomain(sig));
+    case TrustSignatureTrust::Complete:
+        return i18nc("Certifies this key as fully trusted introducer for 'domain name'.",
+                     "Certifies this key as fully trusted introducer for '%1'.", trustSignatureDomain(sig));
+    default:
+        return {};
+    }
+#else
+    return {};
+#endif
+}
diff --git a/src/utils/formatting.h b/src/utils/formatting.h
index 4407ffdb3..361cf494c 100644
--- a/src/utils/formatting.h
+++ b/src/utils/formatting.h
@@ -1,158 +1,165 @@
 /* -*- mode: c++; c-basic-offset:4 -*-
     utils/formatting.h
 
     This file is part of Kleopatra, the KDE keymanager
     SPDX-FileCopyrightText: 2007 Klarälvdalens Datakonsult AB
+    SPDX-FileCopyrightText: 2021 g10 Code GmbH
+    SPDX-FileContributor: Ingo Klöcker <dev@ingo-kloecker.de>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #pragma once
 
 #include <gpgme++/key.h>
 
 #include <kleo_export.h>
 
 class QString;
 #include <QStringList>
 class QDate;
 class QIcon;
 
 namespace GpgME
 {
 class Import;
 }
 
 namespace Kleo
 {
 class KeyGroup;
 
 namespace Formatting
 {
 
 KLEO_EXPORT QString prettyNameAndEMail(int proto, const char *id, const char *name, const char *email, const char *comment);
 KLEO_EXPORT QString prettyNameAndEMail(int proto, const QString &id, const QString &name, const QString &email, const QString &comment);
 KLEO_EXPORT QString prettyNameAndEMail(const GpgME::Key &key);
 KLEO_EXPORT QString prettyNameAndEMail(const GpgME::UserID &key);
 
 KLEO_EXPORT QString prettyUserID(const GpgME::UserID &uid);
 KLEO_EXPORT QString prettyKeyID(const char *id);
 
 KLEO_EXPORT QString prettyName(int proto, const char *id, const char *name, const char *comment);
 KLEO_EXPORT QString prettyName(const GpgME::Key &key);
 KLEO_EXPORT QString prettyName(const GpgME::UserID &uid);
 KLEO_EXPORT QString prettyName(const GpgME::UserID::Signature &sig);
 
 KLEO_EXPORT QString prettyEMail(const char *email, const char *id);
 KLEO_EXPORT QString prettyEMail(const GpgME::Key &key);
 KLEO_EXPORT QString prettyEMail(const GpgME::UserID &uid);
 KLEO_EXPORT QString prettyEMail(const GpgME::UserID::Signature &sig);
 
 /* Formats a fingerprint or keyid into groups of four */
 KLEO_EXPORT QString prettyID(const char *id);
 
 enum ToolTipOption {
     KeyID            = 0x001,
     Validity         = 0x002,
     StorageLocation  = 0x004,
     SerialNumber     = 0x008,
     Issuer           = 0x010,
     Subject          = 0x020,
     ExpiryDates      = 0x040,
     CertificateType  = 0x080,
     CertificateUsage = 0x100,
     Fingerprint      = 0x200,
     UserIDs          = 0x400,
     OwnerTrust       = 0x800,
     Subkeys          = 0x1000,
 
     AllOptions = 0xffff
 };
 
 KLEO_EXPORT QString toolTip(const GpgME::Key &key, int opts);
 KLEO_EXPORT QString toolTip(const Kleo::KeyGroup &group, int opts);
 
 KLEO_EXPORT QString expirationDateString(const GpgME::Key &key);
 KLEO_EXPORT QString expirationDateString(const GpgME::Subkey &subkey);
 KLEO_EXPORT QString expirationDateString(const GpgME::UserID::Signature &sig);
 KLEO_EXPORT QDate expirationDate(const GpgME::Key &key);
 KLEO_EXPORT QDate expirationDate(const GpgME::Subkey &subkey);
 KLEO_EXPORT QDate expirationDate(const GpgME::UserID::Signature &sig);
 
 KLEO_EXPORT QString creationDateString(const GpgME::Key &key);
 KLEO_EXPORT QString creationDateString(const GpgME::Subkey &subkey);
 KLEO_EXPORT QString creationDateString(const GpgME::UserID::Signature &sig);
 KLEO_EXPORT QDate creationDate(const GpgME::Key &key);
 KLEO_EXPORT QDate creationDate(const GpgME::Subkey &subkey);
 KLEO_EXPORT QDate creationDate(const GpgME::UserID::Signature &sig);
 
 /* Convert a GPGME style time to a localized string */
 KLEO_EXPORT QString dateString(time_t t);
 
 KLEO_EXPORT QString displayName(GpgME::Protocol prot);
 KLEO_EXPORT QString type(const GpgME::Key &key);
 KLEO_EXPORT QString type(const GpgME::Subkey &subkey);
 KLEO_EXPORT QString type(const Kleo::KeyGroup &group);
 
 KLEO_EXPORT QString ownerTrustShort(const GpgME::Key &key);
 KLEO_EXPORT QString ownerTrustShort(GpgME::Key::OwnerTrust trust);
 
 KLEO_EXPORT QString validityShort(const GpgME::Subkey &subkey);
 KLEO_EXPORT QString validityShort(const GpgME::UserID &uid);
 KLEO_EXPORT QString validityShort(const GpgME::UserID::Signature &sig);
 KLEO_EXPORT QIcon   validityIcon(const GpgME::UserID::Signature &sig);
 /* A sentence about the validity of the UserID */
 KLEO_EXPORT QString validity(const GpgME::UserID &uid);
 KLEO_EXPORT QString validity(const Kleo::KeyGroup &group);
 KLEO_EXPORT QIcon validityIcon(const Kleo::KeyGroup &group);
 
 KLEO_EXPORT QString formatForComboBox(const GpgME::Key &key);
 
 KLEO_EXPORT QString formatKeyLink(const GpgME::Key &key);
 
 KLEO_EXPORT QString signatureToString(const GpgME::Signature &sig, const GpgME::Key &key);
 
 KLEO_EXPORT const char *summaryToString(const GpgME::Signature::Summary summary);
 
 KLEO_EXPORT QString importMetaData(const GpgME::Import &import);
 KLEO_EXPORT QString importMetaData(const GpgME::Import &import, const QStringList &sources);
 
 KLEO_EXPORT QString formatOverview(const GpgME::Key &key);
 KLEO_EXPORT QString usageString(const GpgME::Subkey &subkey);
 KLEO_EXPORT QString summaryLine(const GpgME::Key &key);
 KLEO_EXPORT QString summaryLine(const KeyGroup &group);
 
 KLEO_EXPORT QIcon iconForUid(const GpgME::UserID &uid);
 
 /* Is the key valid i.e. are all uids fully trusted?  */
 KLEO_EXPORT bool uidsHaveFullValidity(const GpgME::Key &key);
 
 /* The compliance mode of the gnupg system. Empty if compliance
  * mode is not set. */
 KLEO_EXPORT QString complianceMode();
 
 /* Is the given key in compliance with CO_DE_VS?  */
 KLEO_EXPORT bool isKeyDeVs(const GpgME::Key &key);
 /* Localized string describing the name of the VS-NfD Compliance filter. If
  * compliant is false the name of the not Compliant filter.
  *
  * This is required to make the string configurable which is
  * a common request from users because VS-NfD compliance is called
  * differently in different enviornments. E.g NATO RESTRICTED or
  * EU RESTRICTED. */
 KLEO_EXPORT QString deVsString (bool compliant = true);
 
 /* A sentence if the key confirms to the current compliance mode */
 KLEO_EXPORT QString complianceStringForKey(const GpgME::Key &key);
 
 /* A single word for use in keylists to describe the validity of the
  * given key, including any conformance statements relevant to the
  * current conformance mode.  */
 KLEO_EXPORT QString complianceStringShort(const GpgME::Key &key);
 KLEO_EXPORT QString complianceStringShort(const Kleo::KeyGroup &group);
 
 /* The origin of the key mapped to a localized string */
 KLEO_EXPORT QString origin(int o);
+
+/* Human-readable trust signature scope (for trust signature regexp created by GnuPG) */
+KLEO_EXPORT QString trustSignatureDomain(const GpgME::UserID::Signature &sig);
+/* Summary of trust signature properties */
+KLEO_EXPORT QString trustSignature(const GpgME::UserID::Signature &sig);
 }
 }