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/**
* Copyright (C) 2021-2024 Saturneric <eric@bktus.com>
*
* This file is part of GpgFrontend.
*
* GpgFrontend 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 3 of the License, or
* (at your option) any later version.
*
* GpgFrontend 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 GpgFrontend. If not, see <https://www.gnu.org/licenses/>.
*
* The initial version of the source code is inherited from
* the gpg4usb project, which is under GPL-3.0-or-later.
*
* All the source code of GpgFrontend was modified and released by
* Saturneric <eric@bktus.com> starting on May 12, 2021.
*
* SPDX-License-Identifier: GPL-3.0-or-later
*
*/
#include "ImCodec.h"
#include <QCoreApplication>
#include <QJsonArray>
#include <QJsonDocument>
#include <QJsonObject>
#include "GFModuleTr.h"
#include "ImToken.h"
using namespace Qt::StringLiterals;
namespace ImCodec {
namespace {
constexpr char kPhraseBlobVersion = '\x01';
/**
* @brief The "Instant Messaging" card: how the token is framed and, above
* all, whether a shared book phrase is in use -- the default book only hides
* the format from naive scanners, so it is reported as a warning.
*/
auto BookCard(const QString& phrase, qsizetype payload, qsizetype token_len)
-> QJsonObject {
const bool configured = !phrase.isEmpty();
QJsonArray fields;
const auto add = [&fields](const QString& k, const QString& v) {
fields.append(QJsonArray{k, v});
};
add(GTrC::tr("Encoding"), u"Base58 (Bitcoin/IPFS)"_s);
add(GTrC::tr("Container Format"),
QString("v%1").arg(ImToken::FormatVersion()));
add(GTrC::tr("Message Book"),
configured ? GTrC::tr("Shared phrase (Argon2id)")
: GTrC::tr("Default, no shared phrase set"));
// Lets both sides confirm they are on the same book. Only meaningful with a
// phrase: everyone shares the default book, so its digest says nothing.
if (configured) {
add(GTrC::tr("Book Fingerprint"), ImToken::BookFingerprintOf(phrase));
} else {
add(GTrC::tr("Set a Phrase"), GTrC::tr("Settings > Instant Messaging"));
}
if (payload > 0) {
add(GTrC::tr("OpenPGP Payload"), GTrC::tr("%1 bytes").arg(payload));
}
if (token_len > 0) {
add(GTrC::tr("Token Length"), GTrC::tr("%1 characters").arg(token_len));
}
if (payload > 0 && token_len > 0) {
// Random padding plus Base58 expansion. The padding part is deliberately
// random, so this ratio does not pin down the true payload length.
const auto ratio =
static_cast<double>(token_len) / static_cast<double>(payload);
add(GTrC::tr("Wire Overhead"),
QString("+%1%").arg((ratio * 100.0) - 100.0, 0, 'f', 0));
}
return QJsonObject{{u"title"_s, GTrC::tr("Instant Messaging")},
{u"status"_s, configured ? u"ok"_s : u"warn"_s},
{u"fields"_s, fields}};
}
auto CardsJson(const QJsonObject& card) -> QString {
const QJsonObject payload{
{u"description"_s,
GTrC::tr(
"An Instant Messaging section followed by the OpenPGP result.")},
{u"cards"_s, QJsonArray{card}}};
return QString::fromUtf8(
QJsonDocument(payload).toJson(QJsonDocument::Compact));
}
} // namespace
auto DecodeInput(const QByteArray& input, const QString& phrase) -> Answer {
// The token format rejects ordinary text and armored OpenPGP on its shape
// alone, before the memory-hard derivation.
const auto result = ImToken::Decode(QString::fromUtf8(input), phrase);
if (!result.ok) return {};
Answer a;
a.outcome = Outcome::kHandled;
a.output = result.pgp_message;
a.cards = CardsJson(BookCard(phrase, 0, 0));
return a;
}
auto EncodeOutput(const QByteArray& pgp, const QString& phrase) -> Answer {
Answer a;
a.outcome = Outcome::kFailed;
// The payload limit exists so a token we emit is one we can read back.
// Checked here so the user is told what went wrong and what to do about it.
const auto limit = ImToken::MaxPayloadBytes();
if (pgp.size() > limit) {
a.error = GTrC::tr(
"This message is too long to send as an instant message.\n\n"
"The encrypted message is %1 bytes, and the "
"instant-messaging format carries at most %2. Shorten the "
"text, or send it as a normal OpenPGP message instead.")
.arg(pgp.size())
.arg(limit);
return a;
}
const auto token = ImToken::Encode(pgp, phrase);
if (token.isEmpty()) {
a.error = GTrC::tr(
"Failed to prepare the instant message: the encrypted "
"message could not be converted into a token.");
return a;
}
a.outcome = Outcome::kHandled;
a.output = token.toUtf8();
a.cards = CardsJson(BookCard(phrase, pgp.size(), token.size()));
return a;
}
auto EncodePhraseBlob(const QString& phrase) -> QByteArray {
QByteArray blob(1, kPhraseBlobVersion);
blob.append(phrase.trimmed().toUtf8());
return blob;
}
auto DecodePhraseBlob(const QByteArray& blob) -> QString {
if (blob.isEmpty() || blob.at(0) != kPhraseBlobVersion) return {};
return QString::fromUtf8(blob.mid(1)).trimmed();
}
} // namespace ImCodec
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