From ef3c516598e35a4e7e7986fb7826e9dabfe6e837 Mon Sep 17 00:00:00 2001
From: Kevin Ottens <kevin.ottens@nextcloud.com>
Date: Mon, 10 Aug 2020 12:45:32 +0200
Subject: [PATCH] Add support for BASE64 encoded '|' when decrypting

Signed-off-by: Kevin Ottens <kevin.ottens@nextcloud.com>
---
 src/libsync/clientsideencryption.cpp | 44 +++++++++++++++++++++-------
 test/testclientsideencryption.cpp    | 36 +++++++++++++++++++++++
 2 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/src/libsync/clientsideencryption.cpp b/src/libsync/clientsideencryption.cpp
index 76017ec9c..2ddb5f1f2 100644
--- a/src/libsync/clientsideencryption.cpp
+++ b/src/libsync/clientsideencryption.cpp
@@ -61,6 +61,31 @@ namespace {
     const char e2e_cert[] = "_e2e-certificate";
     const char e2e_private[] = "_e2e-private";
     const char e2e_mnemonic[] = "_e2e-mnemonic";
+
+    QList<QByteArray> oldCipherFormatSplit(const QByteArray &cipher)
+    {
+        const auto separator = QByteArrayLiteral("fA=="); // BASE64 encoded '|'
+        auto result = QList<QByteArray>();
+
+        auto data = cipher;
+        auto index = data.indexOf(separator);
+        while (index >=0) {
+            result.append(data.left(index));
+            data = data.mid(index + separator.size());
+            index = data.indexOf(separator);
+        }
+
+        result.append(data);
+        return result;
+    }
+
+    QList<QByteArray> splitCipherParts(const QByteArray &data)
+    {
+        const auto isOldFormat = !data.contains('|');
+        const auto parts = isOldFormat ? oldCipherFormatSplit(data) : data.split('|');
+        qCInfo(lcCse()) << "found parts:" << parts << "old format?" << isOldFormat;
+        return parts;
+    }
 } // ns
 
 namespace {
@@ -371,9 +396,7 @@ QByteArray decryptPrivateKey(const QByteArray& key, const QByteArray& data) {
     qCInfo(lcCse()) << "decryptStringSymmetric key: " << key;
     qCInfo(lcCse()) << "decryptStringSymmetric data: " << data;
 
-    const auto parts = data.split('|');
-    qCInfo(lcCse()) << "found parts:" << parts;
-
+    const auto parts = splitCipherParts(data);
     if (parts.size() < 2) {
         qCInfo(lcCse()) << "Not enough parts found";
         return QByteArray();
@@ -450,9 +473,7 @@ QByteArray decryptPrivateKey(const QByteArray& key, const QByteArray& data) {
 
 QByteArray extractPrivateKeySalt(const QByteArray &data)
 {
-    const auto parts = data.split('|');
-    qCInfo(lcCse()) << "found parts:" << parts;
-
+    const auto parts = splitCipherParts(data);
     if (parts.size() < 3) {
         qCInfo(lcCse()) << "Not enough parts found";
         return QByteArray();
@@ -465,11 +486,14 @@ QByteArray decryptStringSymmetric(const QByteArray& key, const QByteArray& data)
     qCInfo(lcCse()) << "decryptStringSymmetric key: " << key;
     qCInfo(lcCse()) << "decryptStringSymmetric data: " << data;
 
-    int sep = data.indexOf('|');
-    qCInfo(lcCse()) << "sep at" << sep;
+    const auto parts = splitCipherParts(data);
+    if (parts.size() < 2) {
+        qCInfo(lcCse()) << "Not enough parts found";
+        return QByteArray();
+    }
 
-    QByteArray cipherTXT64 = data.left(sep);
-    QByteArray ivB64 = data.right(data.size() - sep - 1);
+    QByteArray cipherTXT64 = parts.at(0);
+    QByteArray ivB64 = parts.at(1);
 
     qCInfo(lcCse()) << "decryptStringSymmetric cipherTXT: " << cipherTXT64;
     qCInfo(lcCse()) << "decryptStringSymmetric IV: " << ivB64;
diff --git a/test/testclientsideencryption.cpp b/test/testclientsideencryption.cpp
index 91ecb0da8..2b0ea5a2c 100644
--- a/test/testclientsideencryption.cpp
+++ b/test/testclientsideencryption.cpp
@@ -14,6 +14,11 @@ class TestClientSideEncryption : public QObject
 {
     Q_OBJECT
 
+    QByteArray convertToOldStorageFormat(const QByteArray &data)
+    {
+        return data.split('|').join("fA==");
+    }
+
 private slots:
     void shouldEncryptPrivateKeys()
     {
@@ -59,6 +64,23 @@ private slots:
         QCOMPARE(salt, originalSalt);
     }
 
+    void shouldDecryptPrivateKeysInOldStorageFormat()
+    {
+        // GIVEN
+        const auto encryptionKey = QByteArrayLiteral("foo");
+        const auto originalPrivateKey = QByteArrayLiteral("bar");
+        const auto originalSalt = QByteArrayLiteral("baz");
+        const auto cipher = convertToOldStorageFormat(EncryptionHelper::encryptPrivateKey(encryptionKey, originalPrivateKey, originalSalt));
+
+        // WHEN
+        const auto privateKey = EncryptionHelper::decryptPrivateKey(encryptionKey, cipher);
+        const auto salt = EncryptionHelper::extractPrivateKeySalt(cipher);
+
+        // THEN
+        QCOMPARE(privateKey, originalPrivateKey);
+        QCOMPARE(salt, originalSalt);
+    }
+
     void shouldSymmetricEncryptStrings()
     {
         // GIVEN
@@ -96,6 +118,20 @@ private slots:
         // THEN
         QCOMPARE(data, originalData);
     }
+
+    void shouldSymmetricDecryptStringsInOldStorageFormat()
+    {
+        // GIVEN
+        const auto encryptionKey = QByteArrayLiteral("foo");
+        const auto originalData = QByteArrayLiteral("bar");
+        const auto cipher = convertToOldStorageFormat(EncryptionHelper::encryptStringSymmetric(encryptionKey, originalData));
+
+        // WHEN
+        const auto data = EncryptionHelper::decryptStringSymmetric(encryptionKey, cipher);
+
+        // THEN
+        QCOMPARE(data, originalData);
+    }
 };
 
 QTEST_APPLESS_MAIN(TestClientSideEncryption)
-- 
2.30.2