Store database storage to files, also loading

13 files changed, 645 insertions, 89 deletions

diff --git a/src/Database.cpp b/src/Database.cpp
index 41b0d73..226aa05 100644
--- a/src/Database.cpp
+++ b/src/Database.cpp
@@ -60,9 +60,9 @@ namespace odhtdb
         return DataView(result, allocationSize);
     }
     
-    DatabaseCreateResponse::DatabaseCreateResponse(LocalUser *_nodeAdminUser, const shared_ptr<char*> &_key, const shared_ptr<Hash> &_hash) : 
+    DatabaseCreateResponse::DatabaseCreateResponse(LocalUser *_nodeAdminUser, const shared_ptr<OwnedMemory> &_key, const shared_ptr<Hash> &_hash) : 
         nodeAdminUser(_nodeAdminUser),
-        key(move(_key)),
+        key(_key),
         hash(_hash)
     {
         
@@ -73,7 +73,7 @@ namespace odhtdb
         return nodeAdminUser;
     }
         
-    const shared_ptr<char*> DatabaseCreateResponse::getNodeEncryptionKey() const
+    const shared_ptr<OwnedMemory> DatabaseCreateResponse::getNodeEncryptionKey() const
     {
         return key;
     }
@@ -83,10 +83,11 @@ namespace odhtdb
         return hash;
     }
     
-    Database::Database(const char *bootstrapNodeAddr, u16 port, boost::filesystem::path storageDir) : 
+    Database::Database(const char *bootstrapNodeAddr, u16 port, const boost::filesystem::path &storageDir) : 
         onCreateNodeCallbackFunc(nullptr),
         onAddNodeCallbackFunc(nullptr),
-        onAddUserCallbackFunc(nullptr)
+        onAddUserCallbackFunc(nullptr),
+        databaseStorage(storageDir)
     {
         // TODO: Cache this in storage. It takes pretty long time to generate new identity
         auto identity = dht::crypto::generateIdentity();
@@ -147,43 +148,43 @@ namespace odhtdb
         node.join();
     }
 
-    void Database::seed(const shared_ptr<Hash> hash, const shared_ptr<char*> encryptionKey)
+    void Database::seed(const DatabaseNode &nodeToSeed)
     {
         // TODO: Use cached files and seed those. If none exists, request new files to seed.
         // If nobody requests my cached files in a long time, request new files to seed and remove cached files
         // (only if there are plenty of other seeders for the cached files. This could also cause race issue 
         // where all nodes with a cached file delete it at same time)
         
-        Log::debug("Seeding key: %s", hash->toString().c_str());
-        DhtKey dhtKey(*hash);
+        Log::debug("Seeding key: %s", nodeToSeed.getRequestHash()->toString().c_str());
+        DhtKey dhtKey(*nodeToSeed.getRequestHash());
         
-        node.listen(dhtKey.getNewDataListenerKey(), [this, hash, encryptionKey](const shared_ptr<Value> &value)
+        node.listen(dhtKey.getNewDataListenerKey(), [this, nodeToSeed](const shared_ptr<Value> &value)
         {
             Log::debug("Seed: New data listener received data...");
             const Hash requestHash(value->data.data(), value->data.size());
-            if(requestHash == *hash)
+            if(requestHash == *nodeToSeed.getRequestHash())
                 return true;
                 //return listenCreateData(value, requestHash, encryptionKey);
             else
-                return listenAddData(value, requestHash, encryptionKey);
+                return listenAddData(value, requestHash, nodeToSeed.getRequestHash(), nodeToSeed.getNodeEncryptionKey());
         });
         
         u8 responseKey[OPENDHT_INFOHASH_LEN];
         randombytes_buf(responseKey, OPENDHT_INFOHASH_LEN);
         
         // TODO: If this response key is spammed, generate a new one.
-        node.listen(InfoHash(responseKey, OPENDHT_INFOHASH_LEN), [this, hash, encryptionKey](const shared_ptr<Value> &value)
+        node.listen(InfoHash(responseKey, OPENDHT_INFOHASH_LEN), [this, nodeToSeed](const shared_ptr<Value> &value)
         {
             const Hash requestHash(value->data.data(), value->data.size());
-            if(requestHash == *hash)
-                return listenCreateData(value, requestHash, encryptionKey);
+            if(requestHash == *nodeToSeed.getRequestHash())
+                return listenCreateData(value, requestHash, nodeToSeed.getNodeEncryptionKey());
             else
-                return listenAddData(value, requestHash, encryptionKey);
+                return listenAddData(value, requestHash, nodeToSeed.getRequestHash(), nodeToSeed.getNodeEncryptionKey());
         });
         
         // TODO: Before listening on this key, we should check how many remote peers are also providing this data.
         // This is to prevent too many peers from responding to a request to get old data.
-        node.listen(dhtKey.getRequestOldDataKey(), [this, hash](const shared_ptr<Value> &value)
+        node.listen(dhtKey.getRequestOldDataKey(), [this, nodeToSeed](const shared_ptr<Value> &value)
         {
             Log::debug("Request: Got request to send old data");
             try
@@ -193,10 +194,10 @@ namespace odhtdb
                 u8 requestResponseKey[OPENDHT_INFOHASH_LEN];
                 deserializer.extract(requestResponseKey, OPENDHT_INFOHASH_LEN);
                 
-                auto requestedData = databaseStorage.getStorage(*hash);
+                auto requestedData = databaseStorage.getStorage(*nodeToSeed.getRequestHash());
                 if(!requestedData)
                 {
-                    Log::warn("No data found for hash %s, unable to serve peer", hash->toString().c_str());
+                    Log::warn("No data found for hash %s, unable to serve peer", nodeToSeed.getRequestHash()->toString().c_str());
                     return true;
                 }
                 
@@ -229,7 +230,7 @@ namespace odhtdb
         });
         
         sibs::SafeSerializer serializer;
-        serializer.add((u64)0); // Timestamp in microseconds, fetch data newer than this
+        serializer.add((u64)0); // Timestamp in microseconds, fetch data newer than this. // TODO: Get timestamp from database storage
         serializer.add(responseKey, OPENDHT_INFOHASH_LEN);
         node.put(dhtKey.getRequestOldDataKey(), Value(serializer.getBuffer().data(), serializer.getBuffer().size()), [](bool ok)
         {
@@ -241,13 +242,13 @@ namespace odhtdb
         //node.listen(ADD_DATA_HASH, bind(&Database::listenAddData, this, _1));
     }
 
-    unique_ptr<DatabaseCreateResponse> Database::create(const std::string &ownerName, const std::string &nodeName)
+    unique_ptr<DatabaseCreateResponse> Database::create(const string &ownerName, const std::string &ownerPlainPassword, const string &nodeName)
     {
         // TODO: Should this be declared static? is there any difference in behavior/performance?
         boost::uuids::random_generator uuidGen;
         auto adminGroupId = uuidGen();
         auto adminGroup = new Group("administrator", adminGroupId.data, ADMIN_PERMISSION);
-        LocalUser *nodeAdminUser = LocalUser::create(Signature::KeyPair(), ownerName, adminGroup);
+        LocalUser *nodeAdminUser = LocalUser::create(Signature::KeyPair(), ownerName, adminGroup, ownerPlainPassword);
         
         // Header
         sibs::SafeSerializer serializer;
@@ -281,10 +282,10 @@ namespace odhtdb
 
             stagedCreateObjects.emplace_back(make_unique<StagedObject>(requestData, hashRequestKey));
             
-            assert(encryptedBody.getKey().size == KEY_BYTE_SIZE);
-            char *key = new char[encryptedBody.getKey().size];
-            memcpy(key, encryptedBody.getKey().data, encryptedBody.getKey().size);
-            return make_unique<DatabaseCreateResponse>(nodeAdminUser, make_shared<char*>(key), hashRequestKey);
+            assert(encryptedBody.getKey().size == ENCRYPTION_KEY_BYTE_SIZE);
+            auto key = make_shared<OwnedMemory>(new char[encryptedBody.getKey().size], encryptedBody.getKey().size);
+            memcpy(key->data, encryptedBody.getKey().data, encryptedBody.getKey().size);
+            return make_unique<DatabaseCreateResponse>(nodeAdminUser, move(key), hashRequestKey);
         }
         catch (EncryptionException &e)
         {
@@ -301,7 +302,7 @@ namespace odhtdb
         serializer.add(timestampMicroseconds);
         serializer.add(DatabaseOperation::ADD_DATA);
         
-        DataView encryptionKey(*nodeInfo.getNodeEncryptionKey(), KEY_BYTE_SIZE);
+        DataView encryptionKey(nodeInfo.getNodeEncryptionKey()->data, ENCRYPTION_KEY_BYTE_SIZE);
         Encryption encryptedBody(dataToAdd, DataView(), encryptionKey);
         DataView requestData = combine(serializer, encryptedBody);
         string signedRequestData = userToPerformActionWith->getPrivateKey().sign(requestData);
@@ -334,7 +335,7 @@ namespace odhtdb
         return nullptr;
     }
     
-    void Database::addUserToGroup(const DatabaseNode &nodeInfo, LocalUser *userToPerformActionWith, const std::string &userToAddName, const Signature::PublicKey &userToAddPublicKey, Group *groupToAddUserTo)
+    void Database::addUser(const DatabaseNode &nodeInfo, LocalUser *userToPerformActionWith, const string &userToAddName, const Signature::PublicKey &userToAddPublicKey, Group *groupToAddUserTo)
     {
         auto groupWithAddUserRights = getGroupWithRightsToAddUserToGroup(userToPerformActionWith->getGroups(), groupToAddUserTo);
         if(!groupWithAddUserRights)
@@ -365,7 +366,7 @@ namespace odhtdb
         Hash requestDataHash(stagedAddObject.data, stagedAddObject.size);
         databaseStorage.appendStorage(*nodeInfo.getRequestHash(), requestDataHash, userToPerformActionWith, timestampMicroseconds, (u8*)stagedAddObject.data, stagedAddObject.size);
         auto userToAdd = RemoteUser::create(userToAddPublicKey, userToAddName, groupToAddUserTo);
-        databaseStorage.addUser(userToAdd, *nodeInfo.getRequestHash());
+        databaseStorage.addUser(*nodeInfo.getRequestHash(), userToAdd);
 
         DatabaseAddUserRequest addUserRequest(&*nodeInfo.getRequestHash(), &requestDataHash, timestampMicroseconds, userToPerformActionWith, userToAdd, groupToAddUserTo);
         if(onAddUserCallbackFunc)
@@ -446,7 +447,7 @@ namespace odhtdb
         return timestamp;
     }
 
-    void Database::deserializeCreateRequest(const std::shared_ptr<dht::Value> &value, const Hash &hash, const shared_ptr<char*> encryptionKey)
+    void Database::deserializeCreateRequest(const shared_ptr<dht::Value> &value, const Hash &hash, const shared_ptr<OwnedMemory> encryptionKey)
     {
         sibs::SafeDeserializer deserializer(value->data.data(), value->data.size());
         u16 packetStructureVersion = deserializer.extract<u16>();
@@ -472,7 +473,7 @@ namespace odhtdb
         uint8_t adminGroupId[16];
         deserializer.extract(adminGroupId, 16);
         
-        if(deserializer.getSize() < NONCE_BYTE_SIZE)
+        if(deserializer.getSize() < ENCRYPTION_NONCE_BYTE_SIZE)
             throw sibs::DeserializeException("Unsigned encrypted body is too small (unable to extract nonce)");
         
         auto adminGroup = new Group("administrator", adminGroupId, ADMIN_PERMISSION);
@@ -480,11 +481,11 @@ namespace odhtdb
         auto creatorUser = RemoteUser::create(userPublicKey, "ENCRYPTED USER NAME", adminGroup);
         databaseStorage.createStorage(hash, adminGroup, creationDate, value->data.data(), value->data.size());
         
-        u8 nonce[NONCE_BYTE_SIZE];
-        deserializer.extract(nonce, NONCE_BYTE_SIZE);
+        u8 nonce[ENCRYPTION_NONCE_BYTE_SIZE];
+        deserializer.extract(nonce, ENCRYPTION_NONCE_BYTE_SIZE);
         
         DataView dataToDecrypt((void*)deserializer.getBuffer(), deserializer.getSize());
-        Decryption decryptedBody(dataToDecrypt, DataView(nonce, NONCE_BYTE_SIZE), DataView(*encryptionKey, KEY_BYTE_SIZE));
+        Decryption decryptedBody(dataToDecrypt, DataView(nonce, ENCRYPTION_NONCE_BYTE_SIZE), DataView(encryptionKey->data, ENCRYPTION_KEY_BYTE_SIZE));
         sibs::SafeDeserializer bodyDeserializer((const u8*)decryptedBody.getDecryptedText().data, decryptedBody.getDecryptedText().size);
         
         u8 creatorNameLength = bodyDeserializer.extract<u8>();
@@ -513,7 +514,7 @@ namespace odhtdb
         return false;
     }
 
-    void Database::deserializeAddRequest(const std::shared_ptr<dht::Value> &value, const Hash &requestDataHash, const shared_ptr<char*> encryptionKey)
+    void Database::deserializeAddRequest(const shared_ptr<dht::Value> &value, const Hash &requestDataHash, const std::shared_ptr<Hash> &nodeHash, const shared_ptr<OwnedMemory> encryptionKey)
     {
         sibs::SafeDeserializer deserializer(value->data.data(), value->data.size());
         char creatorPublicKeyRaw[PUBLIC_KEY_NUM_BYTES];
@@ -541,7 +542,7 @@ namespace odhtdb
             throw sibs::DeserializeException("Packet is from the future");
         
         DatabaseOperation operation = deserializerUnsigned.extract<DatabaseOperation>();
-        
+#if 0
         const Hash *node = databaseStorage.getNodeByUserPublicKey(creatorPublicKey);
         if(!node)
         {
@@ -551,21 +552,21 @@ namespace odhtdb
             databaseStorage.addToQuarantine(requestDataHash, creatorPublicKey, creationDate, value->data.data(), value->data.size());
             throw RequestQuarantineException();
         }
-        
-        auto creatorUser = databaseStorage.getUserByPublicKey(creatorPublicKey);
+#endif
+        auto creatorUser = databaseStorage.getUserByPublicKey(*nodeHash, creatorPublicKey);
         // TODO: Verify there isn't already data with same timestamp for this node. Same for quarantine.
         // TODO: We might receive 'add' data packet before 'create'. If that happens, we should put it in quarantine and process it later.
-        databaseStorage.appendStorage(*node, requestDataHash, creatorUser, creationDate, value->data.data(), value->data.size());
+        databaseStorage.appendStorage(*nodeHash, requestDataHash, creatorUser, creationDate, value->data.data(), value->data.size());
         
         if(operation == DatabaseOperation::ADD_DATA)
         {
-            if(deserializerUnsigned.getSize() < NONCE_BYTE_SIZE)
+            if(deserializerUnsigned.getSize() < ENCRYPTION_NONCE_BYTE_SIZE)
                 throw sibs::DeserializeException("Unsigned encrypted body is too small (unable to extract nonce)");
             
-            u8 nonce[NONCE_BYTE_SIZE];
-            deserializerUnsigned.extract(nonce, NONCE_BYTE_SIZE);
+            u8 nonce[ENCRYPTION_NONCE_BYTE_SIZE];
+            deserializerUnsigned.extract(nonce, ENCRYPTION_NONCE_BYTE_SIZE);
             DataView dataToDecrypt((void*)deserializerUnsigned.getBuffer(), deserializerUnsigned.getSize());
-            Decryption decryptedBody(dataToDecrypt, DataView(nonce, NONCE_BYTE_SIZE), DataView(*encryptionKey, KEY_BYTE_SIZE));
+            Decryption decryptedBody(dataToDecrypt, DataView(nonce, ENCRYPTION_NONCE_BYTE_SIZE), DataView(encryptionKey->data, ENCRYPTION_KEY_BYTE_SIZE));
             
             if(!isUserAllowedToAddData(creatorUser))
             {
@@ -582,7 +583,7 @@ namespace odhtdb
             }
             
             Log::debug("Got add object, timestamp: %zu, data: %.*s", creationDate, decryptedBody.getDecryptedText().size, decryptedBody.getDecryptedText().data);
-            const DatabaseAddNodeRequest addNodeRequest(node, &requestDataHash, creationDate, creatorUser, decryptedBody.getDecryptedText());
+            const DatabaseAddNodeRequest addNodeRequest(&*nodeHash, &requestDataHash, creationDate, creatorUser, decryptedBody.getDecryptedText());
             if(onAddNodeCallbackFunc)
                 onAddNodeCallbackFunc(addNodeRequest);
         }
@@ -600,11 +601,13 @@ namespace odhtdb
             uint8_t groupId[16];
             deserializerUnsigned.extract(groupId, 16);
             
-            auto group = databaseStorage.getGroupById(groupId);
+            auto group = databaseStorage.getGroupById(*nodeHash, groupId);
             if(group)
             {
                 auto user = RemoteUser::create(userToAddPublicKey, name, group);
-                databaseStorage.addUser(user, *node);
+                // TODO: What if we receive packets in wrong order? (maliciously or non-maliciously). You would be able to register a user to a group with given name
+                // and further registration would be dropped (even if that is the correct one)
+                if(!databaseStorage.addUser(*nodeHash, user)) return;
                 
                 auto creatorUserGroupWithRights = getGroupWithRightsToAddUserToGroup(creatorUser->getGroups(), group);
                 if(!creatorUserGroupWithRights)
@@ -622,7 +625,7 @@ namespace odhtdb
                 }
                 
                 Log::debug("Got add user object, timestamp: %zu, user added: %.*s", creationDate, nameLength, name.c_str());
-                DatabaseAddUserRequest addUserRequest(node, &requestDataHash, creationDate, creatorUser, user, group);
+                DatabaseAddUserRequest addUserRequest(&*nodeHash, &requestDataHash, creationDate, creatorUser, user, group);
                 if(onAddUserCallbackFunc)
                     onAddUserCallbackFunc(addUserRequest);
             }
@@ -639,7 +642,7 @@ namespace odhtdb
         }  
     }
 
-    bool Database::listenCreateData(std::shared_ptr<dht::Value> value, const Hash &hash, const shared_ptr<char*> encryptionKey)
+    bool Database::listenCreateData(shared_ptr<dht::Value> value, const Hash &hash, const shared_ptr<OwnedMemory> encryptionKey)
     {
         Log::debug("Got create data");
         try
@@ -655,12 +658,12 @@ namespace odhtdb
         return true;
     }
 
-    bool Database::listenAddData(std::shared_ptr<dht::Value> value, const Hash &requestDataHash, const shared_ptr<char*> encryptionKey)
+    bool Database::listenAddData(shared_ptr<dht::Value> value, const Hash &requestDataHash, const std::shared_ptr<Hash> nodeHash, const shared_ptr<OwnedMemory> encryptionKey)
     {
         Log::debug("Got add data");
         try
         {
-            deserializeAddRequest(value, requestDataHash, encryptionKey);
+            deserializeAddRequest(value, requestDataHash, nodeHash, encryptionKey);
             //Log::debug("Got add object, timestamp: %zu", addObject.timestamp);
         }
         catch (RequestQuarantineException &e)
@@ -674,17 +677,17 @@ namespace odhtdb
         return true;
     }
 
-    void Database::setOnCreateNodeCallback(std::function<void(const DatabaseCreateNodeRequest&)> callbackFunc)
+    void Database::setOnCreateNodeCallback(function<void(const DatabaseCreateNodeRequest&)> callbackFunc)
     {
         onCreateNodeCallbackFunc = callbackFunc;
     }
 
-    void Database::setOnAddNodeCallback(std::function<void(const DatabaseAddNodeRequest&)> callbackFunc)
+    void Database::setOnAddNodeCallback(function<void(const DatabaseAddNodeRequest&)> callbackFunc)
     {
         onAddNodeCallbackFunc = callbackFunc;
     }
 
-    void Database::setOnAddUserCallback(std::function<void(const DatabaseAddUserRequest&)> callbackFunc)
+    void Database::setOnAddUserCallback(function<void(const DatabaseAddUserRequest&)> callbackFunc)
     {
         onAddUserCallbackFunc = callbackFunc;
     }
diff --git a/src/DatabaseStorage.cpp b/src/DatabaseStorage.cpp
index 212ca0f..bd98b8b 100644
--- a/src/DatabaseStorage.cpp
+++ b/src/DatabaseStorage.cpp
@@ -1,13 +1,28 @@
 #include "../include/odhtdb/DatabaseStorage.hpp"
-#include "../include/odhtdb/User.hpp"
+#include "../include/odhtdb/RemoteUser.hpp"
+#include "../include/odhtdb/LocalUser.hpp"
+#include "../include/odhtdb/LocalUserEncrypted.hpp"
 #include "../include/odhtdb/Group.hpp"
+#include "../include/odhtdb/FileUtils.hpp"
+#include "../include/odhtdb/bin2hex.hpp"
+#include "../include/odhtdb/PasswordHash.hpp"
+#include "../include/odhtdb/Log.hpp"
 #include <cstring>
 #include <chrono>
+#include <boost/filesystem/convenience.hpp>
+#include <sibs/SafeSerializer.hpp>
+#include <sodium/randombytes.h>
 
 using namespace std;
 
 namespace odhtdb
 {
+    enum StorageType : u8
+    {
+        STORAGE_TYPE_CREATE,
+        STORAGE_TYPE_APPEND
+    };
+    
     const u64 QUARANTINE_STORAGE_TIME_MICROSECONDS = 60 * 1.0e6;
     
     DatabaseStorageObject::DatabaseStorageObject(DataView &_data, u64 _timestamp, const Signature::PublicKey &_creatorPublicKey) : 
@@ -23,6 +38,263 @@ namespace odhtdb
         storedTimestamp = chrono::duration_cast<chrono::microseconds>(time).count();
     }
     
+    DatabaseStorage::DatabaseStorage(const boost::filesystem::path &storagePath) : 
+        groupsFilePath(storagePath / "groups"),
+        usersFilePath(storagePath / "users"),
+        dataFilePath(storagePath / "data"),
+        metadataFilePath(storagePath / "metadata")
+    {
+        boost::filesystem::create_directories(storagePath);
+        
+        bool metadataLoaded = false;
+        try
+        {
+            loadMetadataFromFile();
+            metadataLoaded = true;
+            loadGroupsFromFile();
+            loadUsersFromFile();
+            loadDataFromFile();
+            //loadQuarantineFromFile();
+        }
+        catch(FileException &e)
+        {
+            Log::warn("Failed to load data from file: %s, reason: %s. Ignoring...", dataFilePath.string().c_str(), e.what());
+            if(!metadataLoaded)
+            {
+                sibs::SafeSerializer metadataSerializer;
+                metadataSerializer.add((u16)0); // Storage version
+                randombytes_buf(passwordSalt, PASSWORD_SALT_LEN);
+                metadataSerializer.add(passwordSalt, PASSWORD_SALT_LEN);
+                fileAppend(metadataFilePath, { metadataSerializer.getBuffer().data(), metadataSerializer.getBuffer().size() });
+            }
+        }
+    }
+    
+    void DatabaseStorage::loadGroupsFromFile()
+    {
+        if(!boost::filesystem::exists(groupsFilePath)) return;
+        
+        OwnedMemory groupsFileContent = fileGetContent(groupsFilePath);
+        sibs::SafeDeserializer deserializer((u8*)groupsFileContent.data, groupsFileContent.size);
+        
+        while(!deserializer.empty())
+        {
+            Hash nodeHash;
+            deserializer.extract((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+            
+            DataViewMap<Group*> *groupByIdMap = nullptr;
+            auto groupByIdMapIt = nodeGroupByIdMap.find(nodeHash);
+            if(groupByIdMapIt == nodeGroupByIdMap.end())
+            {
+                groupByIdMap = new DataViewMap<Group*>();
+                nodeGroupByIdMap[nodeHash] = groupByIdMap;
+            }
+            else
+                groupByIdMap = groupByIdMapIt->second;
+            
+            u8 groupNameSize = deserializer.extract<u8>();
+            string groupName;
+            groupName.resize(groupNameSize);
+            deserializer.extract((u8*)&groupName[0], groupNameSize);
+            
+            u8 groupId[GROUP_ID_LENGTH];
+            deserializer.extract(groupId, GROUP_ID_LENGTH);
+            
+            u8 permissionLevel = deserializer.extract<u8>();
+            u32 permissionFlags = deserializer.extract<u32>();
+            
+            Group *group = new Group(groupName, groupId, { permissionLevel, permissionFlags });
+            (*groupByIdMap)[group->getId()] = group;
+            
+            string groupIdStr = bin2hex((const char*)groupId, GROUP_ID_LENGTH);
+            Log::debug("DatabaseStorage: Loaded group from file: %s", groupIdStr.c_str());
+        }
+    }
+    
+    void DatabaseStorage::loadUsersFromFile()
+    {
+        if(!boost::filesystem::exists(usersFilePath)) return;
+        
+        OwnedMemory usersFileContent = fileGetContent(usersFilePath);
+        sibs::SafeDeserializer deserializer((u8*)usersFileContent.data, usersFileContent.size);
+        
+        while(!deserializer.empty())
+        {
+            Hash nodeHash;
+            deserializer.extract((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+            
+            Signature::MapPublicKey<UserData*> *publicKeyUserDataMap = nullptr;
+            auto publicKeyUserDataMapIt = nodePublicKeyUserDataMap.find(nodeHash);
+            if(publicKeyUserDataMapIt == nodePublicKeyUserDataMap.end())
+            {
+                publicKeyUserDataMap = new Signature::MapPublicKey<UserData*>();
+                nodePublicKeyUserDataMap[nodeHash] = publicKeyUserDataMap;
+            }
+            else
+                publicKeyUserDataMap = publicKeyUserDataMapIt->second;
+            
+            DataViewMap<Group*> *groupByIdMap = nullptr;
+            auto groupByIdMapIt = nodeGroupByIdMap.find(nodeHash);
+            if(groupByIdMapIt == nodeGroupByIdMap.end())
+            {
+                groupByIdMap = new DataViewMap<Group*>();
+                nodeGroupByIdMap[nodeHash] = groupByIdMap;
+            }
+            else
+                groupByIdMap = groupByIdMapIt->second;
+            
+            User::Type userType = deserializer.extract<User::Type>();
+            
+            u8 usernameSize = deserializer.extract<u8>();
+            string username;
+            username.resize(usernameSize);
+            deserializer.extract((u8*)&username[0], usernameSize);
+            
+            u8 userPublicKeyRaw[PUBLIC_KEY_NUM_BYTES];
+            deserializer.extract(userPublicKeyRaw, PUBLIC_KEY_NUM_BYTES);
+            Signature::PublicKey userPublicKey((const char*)userPublicKeyRaw, PUBLIC_KEY_NUM_BYTES);
+            
+            UserData *userData = new UserData();
+            if(userType == User::Type::LOCAL)
+            {
+                EncryptedPrivateKey encryptedPrivateKey;
+                deserializer.extract(encryptedPrivateKey.nonce, ENCRYPTION_NONCE_BYTE_SIZE);
+                deserializer.extract(encryptedPrivateKey.encryptedPrivateKey, 16 + PRIVATE_KEY_NUM_BYTES);
+                userData->user = LocalUserEncrypted::create(userPublicKey, encryptedPrivateKey, username, nullptr);
+            }
+            else
+            {
+                userData->user = RemoteUser::create(userPublicKey, username, nullptr);
+            }
+            
+            u8 numGroups = deserializer.extract<u8>();
+            for(int i = 0; i < numGroups; ++i)
+            {
+                u8 groupId[GROUP_ID_LENGTH];
+                deserializer.extract(groupId, GROUP_ID_LENGTH);
+                
+                auto groupIt = groupByIdMap->find(DataView(groupId, GROUP_ID_LENGTH));
+                if(groupIt == groupByIdMap->end())
+                {
+                    string errMsg = "User group with id ";
+                    errMsg += bin2hex((const char*)groupId, GROUP_ID_LENGTH);
+                    errMsg += " does not exist";
+                    throw DatabaseStorageCorrupt(errMsg);
+                }
+                userData->user->addToGroup(groupIt->second);
+            }
+            
+            (*publicKeyUserDataMap)[userData->user->getPublicKey()] = userData;
+        }
+    }
+    
+    void DatabaseStorage::loadStorageCreate(sibs::SafeDeserializer &deserializer)
+    {
+        u64 timestamp = deserializer.extract<u64>();
+        
+        u8 groupId[GROUP_ID_LENGTH];
+        deserializer.extract(groupId, GROUP_ID_LENGTH);
+        
+        u32 dataSize = deserializer.extract<u32>();
+        u8 *data = new u8[dataSize];
+        deserializer.extract(data, dataSize);
+        
+        Hash nodeHash;
+        deserializer.extract((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+        
+        auto groupByIdMapIt = nodeGroupByIdMap.find(nodeHash);
+        if(groupByIdMapIt == nodeGroupByIdMap.end())
+        {
+            string errMsg = "No groups exists in node ";
+            errMsg += nodeHash.toString();
+            throw DatabaseStorageCorrupt(errMsg);
+        }
+        
+        auto groupIt = groupByIdMapIt->second->find(DataView(groupId, GROUP_ID_LENGTH));
+        if(groupIt == groupByIdMapIt->second->end())
+        {
+            string errMsg = "User group with id ";
+            errMsg += bin2hex((const char*)groupId, GROUP_ID_LENGTH);
+            errMsg += " does not exist in node ";
+            errMsg += nodeHash.toString();
+            throw DatabaseStorageCorrupt(errMsg);
+        }
+        
+        DatabaseStorageObjectList *databaseStorageObjectList = new DatabaseStorageObjectList();
+        databaseStorageObjectList->createdTimestamp = timestamp;
+        databaseStorageObjectList->groups.push_back(groupIt->second);
+        databaseStorageObjectList->data = DataView(data, dataSize);
+        storageMap[nodeHash] = databaseStorageObjectList;
+    }
+    
+    void DatabaseStorage::loadStorageAppend(sibs::SafeDeserializer &deserializer)
+    {
+        u64 timestamp = deserializer.extract<u64>();
+        
+        u8 creatorPublicKeyRaw[PUBLIC_KEY_NUM_BYTES];
+        deserializer.extract(creatorPublicKeyRaw, PUBLIC_KEY_NUM_BYTES);
+        Signature::PublicKey creatorPublicKey((const char*)creatorPublicKeyRaw, PUBLIC_KEY_NUM_BYTES);
+        
+        u32 dataSize = deserializer.extract<u32>();
+        u8 *data = new u8[dataSize];
+        deserializer.extract(data, dataSize);
+        
+        Hash nodeHash;
+        deserializer.extract((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+        
+        Hash dataHash;
+        deserializer.extract((u8*)dataHash.getData(), HASH_BYTE_SIZE);
+        storedDataHash.insert(dataHash);
+        
+        auto storageIt = storageMap.find(nodeHash);
+        if(storageIt == storageMap.end())
+        {
+            string errMsg = "Database storage with hash ";
+            errMsg += nodeHash.toString();
+            errMsg += " not found";
+            throw DatabaseStorageCorrupt(errMsg);
+        }
+        
+        DataView storageData { data, dataSize };
+        DatabaseStorageObject *databaseStorageObject = new DatabaseStorageObject(storageData, timestamp, creatorPublicKey);
+        storageIt->second->objects.push_back(databaseStorageObject);
+    }
+    
+    void DatabaseStorage::loadDataFromFile()
+    {
+        if(!boost::filesystem::exists(dataFilePath)) return;
+        
+        OwnedMemory dataFileContent = fileGetContent(dataFilePath);
+        sibs::SafeDeserializer deserializer((u8*)dataFileContent.data, dataFileContent.size);
+        
+        while(!deserializer.empty())
+        {
+            StorageType storageType = deserializer.extract<StorageType>();
+            switch(storageType)
+            {
+                case STORAGE_TYPE_CREATE:
+                    loadStorageCreate(deserializer);
+                    break;
+                case STORAGE_TYPE_APPEND:
+                    loadStorageAppend(deserializer);
+                    break;
+            }
+        }
+    }
+    
+    void DatabaseStorage::loadMetadataFromFile()
+    {
+        OwnedMemory metadataFileContent = fileGetContent(metadataFilePath);
+        sibs::SafeDeserializer deserializer((u8*)metadataFileContent.data, metadataFileContent.size);
+        
+        u16 storageVersion = deserializer.extract<u16>();
+        
+        u8 passwordSalt[PASSWORD_SALT_LEN];
+        deserializer.extract(passwordSalt, PASSWORD_SALT_LEN);
+        
+        assert(deserializer.empty());
+    }
+    
     void DatabaseStorage::createStorage(const Hash &hash, Group *creatorGroup, u64 timestamp, const u8 *data, usize dataSize)
     {
         if(storageMap.find(hash) != storageMap.end())
@@ -33,18 +305,30 @@ namespace odhtdb
             throw DatabaseStorageAlreadyExists(errMsg);
         }
         
+        addGroup(hash, creatorGroup);
+        for(auto user : creatorGroup->getUsers())
+        {
+            addUser(hash, (User*)user);
+        }
+        
         DatabaseStorageObjectList *databaseStorageObjectList = new DatabaseStorageObjectList();
         databaseStorageObjectList->createdTimestamp = timestamp;
         databaseStorageObjectList->groups.push_back(creatorGroup);
         databaseStorageObjectList->data = DataView(new u8[dataSize], dataSize);
         memcpy(databaseStorageObjectList->data.data, data, dataSize);
         storageMap[hash] = databaseStorageObjectList;
-        groupByIdMap[creatorGroup->getId()] = creatorGroup;
         
-        for(auto user : creatorGroup->getUsers())
-        {
-            addUser((User*)user, hash);
-        }
+        sibs::SafeSerializer serializer;
+        serializer.add(STORAGE_TYPE_CREATE);
+        serializer.add(timestamp);
+        serializer.add((u8*)creatorGroup->getId().data, GROUP_ID_LENGTH);
+        
+        serializer.add((u32)dataSize);
+        serializer.add(data, dataSize);
+        
+        serializer.add((u8*)hash.getData(), HASH_BYTE_SIZE);
+        
+        fileAppend(dataFilePath, { serializer.getBuffer().data(), serializer.getBuffer().size() });
     }
     
     void DatabaseStorage::appendStorage(const Hash &nodeHash, const Hash &dataHash, const User *creatorUser, u64 timestamp, const u8 *data, usize dataSize)
@@ -70,6 +354,19 @@ namespace odhtdb
         memcpy(storageData.data, data, dataSize);
         DatabaseStorageObject *databaseStorageObject = new DatabaseStorageObject(storageData, timestamp, creatorUser->getPublicKey());
         it->second->objects.push_back(databaseStorageObject);
+        
+        sibs::SafeSerializer serializer;
+        serializer.add(STORAGE_TYPE_APPEND);
+        serializer.add(timestamp);
+        serializer.add((u8*)creatorUser->getPublicKey().getData(), PUBLIC_KEY_NUM_BYTES);
+        
+        serializer.add((u32)dataSize);
+        serializer.add(data, dataSize);
+        
+        serializer.add((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+        serializer.add((u8*)dataHash.getData(), HASH_BYTE_SIZE);
+        
+        fileAppend(dataFilePath, { serializer.getBuffer().data(), serializer.getBuffer().size() });
     }
     
     void DatabaseStorage::addToQuarantine(const Hash &dataHash, const Signature::PublicKey &creatorPublicKey, u64 timestamp, const u8 *data, usize dataSize)
@@ -88,10 +385,103 @@ namespace odhtdb
         quarantineStorageMap[creatorPublicKey].emplace_back(databaseQuarantineStorageObject);
     }
     
-    void DatabaseStorage::addUser(User *user, const Hash &hash)
+    bool DatabaseStorage::addGroup(const Hash &nodeHash, Group *group)
+    {
+        DataViewMap<Group*> *groupByIdMap = nullptr;
+        auto groupByIdMapIt = nodeGroupByIdMap.find(nodeHash);
+        if(groupByIdMapIt == nodeGroupByIdMap.end())
+        {
+            groupByIdMap = new DataViewMap<Group*>();
+            nodeGroupByIdMap[nodeHash] = groupByIdMap;
+        }
+        else
+            groupByIdMap = groupByIdMapIt->second;
+        
+        if(groupByIdMap->find(group->getId()) != groupByIdMap->end())
+            return false;
+        
+        (*groupByIdMap)[group->getId()] = group;
+        
+        sibs::SafeSerializer serializer;
+        
+        serializer.add((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+        
+        serializer.add((u8)group->getName().size());
+        serializer.add((u8*)group->getName().data(), group->getName().size());
+        
+        serializer.add((u8*)group->getId().data, GROUP_ID_LENGTH);
+        
+        serializer.add(group->getPermission().getPermissionLevel());
+        serializer.add(group->getPermission().getPermissionFlags());
+        
+        fileAppend(groupsFilePath, DataView(serializer.getBuffer().data(), serializer.getBuffer().size()));
+        
+        return true;
+    }
+    
+    bool DatabaseStorage::addUser(const Hash &nodeHash, User *user)
     {
-        userPublicKeyNodeMap[user->getPublicKey()] = new Hash(hash);
-        publicKeyUserMap[user->getPublicKey()] = user;
+        Signature::MapPublicKey<UserData*> *publicKeyUserDataMap = nullptr;
+        auto publicKeyUserDataMapIt = nodePublicKeyUserDataMap.find(nodeHash);
+        if(publicKeyUserDataMapIt == nodePublicKeyUserDataMap.end())
+        {
+            publicKeyUserDataMap = new Signature::MapPublicKey<UserData*>();
+            nodePublicKeyUserDataMap[nodeHash] = publicKeyUserDataMap;
+        }
+        else
+            publicKeyUserDataMap = publicKeyUserDataMapIt->second;
+        
+        if(publicKeyUserDataMap->find(user->getPublicKey()) != publicKeyUserDataMap->end())
+            return false;
+        
+        UserData *userData = new UserData();
+        userData->user = user;
+        if(user->getType() == User::Type::LOCAL)
+        {
+            LocalUser *localUser = static_cast<LocalUser*>(user);
+            //DataView plainPassword((void*)localUser->getPlainPassword().data(), localUser->getPlainPassword().size());
+            OwnedMemory hashedPassword = hashPassword(DataView((void*)localUser->getPlainPassword().data(), localUser->getPlainPassword().size()), DataView(passwordSalt, PASSWORD_SALT_LEN));
+            memcpy(userData->hashedPassword, hashedPassword.data, hashedPassword.size);
+        }
+        else
+        {
+            memset(userData->hashedPassword, 0, HASHED_PASSWORD_LEN);
+        }
+        (*publicKeyUserDataMap)[user->getPublicKey()] = userData;
+        
+        // TODO: Instead of directly saving user to file, maybe user should be added to buffer and then save to file after we have several users (performance improvement)
+        
+        sibs::SafeSerializer serializer;
+        
+        serializer.add((u8*)nodeHash.getData(), HASH_BYTE_SIZE);
+        
+        serializer.add(user->getType());
+        
+        serializer.add((u8)user->getName().size());
+        serializer.add((u8*)user->getName().data(), user->getName().size());
+        
+        serializer.add((u8*)user->getPublicKey().getData(), PUBLIC_KEY_NUM_BYTES);
+        if(user->getType() == User::Type::LOCAL)
+        {
+            LocalUser *localUser = static_cast<LocalUser*>(user);
+            static_assert(HASHED_PASSWORD_LEN == ENCRYPTION_KEY_BYTE_SIZE, "Encryption key size has changed but hashed password size hasn't");
+            Encryption encryptedPrivateKey(DataView((void*)localUser->getPrivateKey().getData(), localUser->getPrivateKey().getSize()), 
+                                                DataView(),
+                                                DataView(userData->hashedPassword, HASHED_PASSWORD_LEN));
+            serializer.add((u8*)encryptedPrivateKey.getNonce().data, ENCRYPTION_NONCE_BYTE_SIZE);
+            assert(16 + PRIVATE_KEY_NUM_BYTES == encryptedPrivateKey.getCipherText().size);
+            serializer.add((u8*)encryptedPrivateKey.getCipherText().data, encryptedPrivateKey.getCipherText().size);
+        }
+        
+        serializer.add((u8)user->getGroups().size());
+        for(Group *group : user->getGroups())
+        {
+            serializer.add((u8*)group->getId().data, GROUP_ID_LENGTH);
+        }
+        
+        fileAppend(usersFilePath, DataView(serializer.getBuffer().data(), serializer.getBuffer().size()));
+        
+        return true;
     }
     
     const DatabaseStorageObjectList* DatabaseStorage::getStorage(const Hash &hash) const
@@ -102,33 +492,41 @@ namespace odhtdb
         return nullptr;
     }
     
-    const Hash* DatabaseStorage::getNodeByUserPublicKey(const Signature::PublicKey &userPublicKey) const
+    Group* DatabaseStorage::getGroupById(const Hash &nodeHash, uint8_t groupId[GROUP_ID_LENGTH])
     {
-        auto it = userPublicKeyNodeMap.find(userPublicKey);
-        if(it != userPublicKeyNodeMap.end())
-            return it->second;
+        auto groupByIdMapIt = nodeGroupByIdMap.find(nodeHash);
+        if(groupByIdMapIt != nodeGroupByIdMap.end())
+        {
+            auto it = groupByIdMapIt->second->find(DataView(groupId, GROUP_ID_LENGTH));
+            if(it != groupByIdMapIt->second->end())
+                return it->second;
+        }
         return nullptr;
     }
     
-    // Returns nullptr if no user with public key exists
-    const User* DatabaseStorage::getUserByPublicKey(const Signature::PublicKey &userPublicKey) const
+    User* DatabaseStorage::getUserByPublicKey(const Hash &nodeHash, Signature::PublicKey &userPublicKey)
     {
-        auto it = publicKeyUserMap.find(userPublicKey);
-        if(it != publicKeyUserMap.end())
-            return it->second;
+        auto publicKeyUserDataMapIt = nodePublicKeyUserDataMap.find(nodeHash);
+        if(publicKeyUserDataMapIt != nodePublicKeyUserDataMap.end())
+        {
+            auto it = publicKeyUserDataMapIt->second->find(userPublicKey);
+            if(it != publicKeyUserDataMapIt->second->end())
+                return it->second->user;
+        }
         return nullptr;
     }
     
-    Group* DatabaseStorage::getGroupById(uint8_t groupId[16])
+    const Signature::MapPublicKey<DatabaseStorage::UserData*>* DatabaseStorage::getUsersData(const Hash &nodeHash) const
     {
-        auto it = groupByIdMap.find(DataView(groupId, 16));
-        if(it != groupByIdMap.end())
-            return it->second;
+        auto publicKeyUserDataMapIt = nodePublicKeyUserDataMap.find(nodeHash);
+        if(publicKeyUserDataMapIt != nodePublicKeyUserDataMap.end())
+            return publicKeyUserDataMapIt->second;
         return nullptr;
     }
     
     void DatabaseStorage::update()
     {
+        // TODO: Modify this to iterate backwards. Because list is sorted in order of timestamp, we can remove data in range
         auto time = chrono::high_resolution_clock::now().time_since_epoch();
         auto timeMicroseconds = chrono::duration_cast<chrono::microseconds>(time).count();
         for(auto mapIt = quarantineStorageMap.begin(); mapIt != quarantineStorageMap.end(); )
diff --git a/src/Encryption.cpp b/src/Encryption.cpp
index 7f8700b..e67c719 100644
--- a/src/Encryption.cpp
+++ b/src/Encryption.cpp
@@ -12,14 +12,14 @@ namespace odhtdb
         
         if(_key.data)
         {
-            if(_key.size != KEY_BYTE_SIZE)
+            if(_key.size != ENCRYPTION_KEY_BYTE_SIZE)
                 throw EncryptionException("Encryption key is wrong size");
             memcpy(key, _key.data, _key.size);
         }
         else
             crypto_aead_xchacha20poly1305_ietf_keygen(key);
         
-        randombytes_buf(nonce, NONCE_BYTE_SIZE);
+        randombytes_buf(nonce, ENCRYPTION_NONCE_BYTE_SIZE);
         if(crypto_aead_xchacha20poly1305_ietf_encrypt(cipherText, &cipherTextLength, (const unsigned char*)data.data, data.size, (const unsigned char*)additionalData.data, additionalData.size, nullptr, nonce, key) < 0)
             throw EncryptionException("Failed to encrypt data");
     }
@@ -31,12 +31,12 @@ namespace odhtdb
     
     DataView Encryption::getKey() const
     {
-        return DataView((void*)key, KEY_BYTE_SIZE);
+        return DataView((void*)key, ENCRYPTION_KEY_BYTE_SIZE);
     }
     
     DataView Encryption::getNonce() const
     {
-        return DataView((void*)nonce, NONCE_BYTE_SIZE);
+        return DataView((void*)nonce, ENCRYPTION_NONCE_BYTE_SIZE);
     }
     
     DataView Encryption::getCipherText() const
@@ -49,10 +49,10 @@ namespace odhtdb
         decryptedText = new unsigned char[data.size];
         decryptedTextLength = data.size;
         
-        if(nonce.size < NONCE_BYTE_SIZE)
+        if(nonce.size < ENCRYPTION_NONCE_BYTE_SIZE)
             throw DecryptionException("Nonce is not big enough");
         
-        if(key.size < KEY_BYTE_SIZE)
+        if(key.size < ENCRYPTION_KEY_BYTE_SIZE)
             throw DecryptionException("Key is not big enough");
         
         if(crypto_aead_xchacha20poly1305_ietf_decrypt(decryptedText, &decryptedTextLength, nullptr, (const unsigned char*)data.data, data.size, nullptr, 0, (const unsigned char*)nonce.data, (const unsigned char*)key.data) < 0)
diff --git a/src/FileUtils.cpp b/src/FileUtils.cpp
new file mode 100644
index 0000000..3a78a63
--- /dev/null
+++ b/src/FileUtils.cpp
@@ -0,0 +1,57 @@
+#include "../include/odhtdb/FileUtils.hpp"
+#include "../include/odhtdb/env.hpp"
+
+using namespace std;
+
+namespace odhtdb
+{
+    OwnedMemory fileGetContent(const boost::filesystem::path &filepath)
+    {
+#if OS_FAMILY == OS_FAMILY_POSIX
+        FILE *file = fopen(filepath.string().c_str(), "rb");
+#else
+        FILE *file = _wfopen(filepath.wstring().c_str(), L"rb");
+#endif
+        if(!file)
+        {
+            int error = errno;
+            string errMsg = "Failed to open file: ";
+            errMsg += filepath.string();
+            errMsg += "; reason: ";
+            errMsg += strerror(error);
+            throw FileException(errMsg);
+        }
+
+        fseek(file, 0, SEEK_END);
+        size_t fileSize = ftell(file);
+        fseek(file, 0, SEEK_SET);
+
+        char *result = new char[fileSize];
+        fread(result, 1, fileSize, file);
+        fclose(file);
+        return { result, fileSize };
+    }
+    
+    void fileAppend(const boost::filesystem::path &filepath, const DataView &data)
+    {
+#if OS_FAMILY == OS_FAMILY_POSIX
+        FILE *file = fopen(filepath.string().c_str(), "ab+");
+#else
+        FILE *file = _wfopen(filepath.wstring().c_str(), L"ab+");
+#endif
+        if(!file)
+        {
+            int error = errno;
+            string errMsg = "Failed to append to file: ";
+            errMsg += filepath.string();
+            errMsg += "; reason: ";
+            errMsg += strerror(error);
+            throw FileException(errMsg);
+        }
+        
+        flockfile(file);
+        setbuf(file, NULL);
+        fwrite(data.data, 1, data.size, file);
+        fclose(file);
+    }
+}
diff --git a/src/Group.cpp b/src/Group.cpp
index caf3e05..a99fdf6 100644
--- a/src/Group.cpp
+++ b/src/Group.cpp
@@ -6,13 +6,13 @@ using namespace std;
 
 namespace odhtdb
 {
-    Group::Group(const string &_name, uint8_t _id[16], const Permission &_permission) : 
+    Group::Group(const string &_name, uint8_t _id[GROUP_ID_LENGTH], const Permission &_permission) : 
         name(_name),
         permission(_permission)
     {
         if(name.size() > 255)
             throw GroupNameTooLongException(name);
-        memcpy(id, _id, 16);
+        memcpy(id, _id, GROUP_ID_LENGTH);
     }
 
     Group::~Group()
@@ -32,7 +32,7 @@ namespace odhtdb
     
     DataView Group::getId() const
     {
-        return { (void*)id, 16 };
+        return { (void*)id, GROUP_ID_LENGTH };
     }
     
     const Permission& Group::getPermission() const
diff --git a/src/LocalUser.cpp b/src/LocalUser.cpp
new file mode 100644
index 0000000..660d09a
--- /dev/null
+++ b/src/LocalUser.cpp
@@ -0,0 +1,12 @@
+#include "../include/odhtdb/LocalUser.hpp"
+
+namespace odhtdb
+{
+    LocalUser::LocalUser(const Signature::KeyPair &_keyPair, const std::string &name, Group *group, const std::string &_plainPassword) : 
+        User(User::Type::LOCAL, name, group), 
+        keyPair(_keyPair),
+        plainPassword(_plainPassword)
+    {
+
+    }
+}
diff --git a/src/LocalUserEncrypted.cpp b/src/LocalUserEncrypted.cpp
new file mode 100644
index 0000000..1c22488
--- /dev/null
+++ b/src/LocalUserEncrypted.cpp
@@ -0,0 +1,27 @@
+#include "../include/odhtdb/LocalUserEncrypted.hpp"
+#include "../include/odhtdb/PasswordHash.hpp"
+#include <cstring>
+
+namespace odhtdb
+{
+    EncryptedPrivateKey::EncryptedPrivateKey()
+    {
+        memset(nonce, 0, ENCRYPTION_NONCE_BYTE_SIZE);
+        memset(encryptedPrivateKey, 0, 16 + PRIVATE_KEY_NUM_BYTES);
+    }
+    
+    EncryptedPrivateKey::EncryptedPrivateKey(const EncryptedPrivateKey &other)
+    {
+        memcpy(nonce, other.nonce, ENCRYPTION_NONCE_BYTE_SIZE);
+        memcpy(encryptedPrivateKey, other.encryptedPrivateKey, 16 + PRIVATE_KEY_NUM_BYTES);
+    }
+    
+    Signature::PrivateKey EncryptedPrivateKey::decrypt(const DataView &plainPassword, const DataView &salt) const
+    {
+        OwnedMemory hashedPassword = hashPassword(plainPassword, salt);
+        Decryption decryptedPrivateKey(DataView((void*)encryptedPrivateKey, 16 + PRIVATE_KEY_NUM_BYTES), 
+                                       DataView((void*)nonce, ENCRYPTION_NONCE_BYTE_SIZE), 
+                                       DataView(hashedPassword.data, hashedPassword.size));
+        return { (const char*)decryptedPrivateKey.getDecryptedText().data, decryptedPrivateKey.getDecryptedText().size };
+    }
+}
diff --git a/src/Log.cpp b/src/Log.cpp
index 9c06a62..0bdc0a6 100644
--- a/src/Log.cpp
+++ b/src/Log.cpp
@@ -2,15 +2,14 @@
 #include <cstdarg>
 #include <mutex>
 
-static std::mutex mutexDebug;
-
 namespace odhtdb
 {
     // TODO: Add color (if output is tty)?
+    static std::mutex mutexLog;
     
     void Log::debug(const char *fmt, ...)
     {
-        std::lock_guard<std::mutex> lock(mutexDebug);
+        std::lock_guard<std::mutex> lock(mutexLog);
         va_list args;
         va_start(args, fmt);
         fputs("Debug: ", stdout);
@@ -21,7 +20,7 @@ namespace odhtdb
     
     void Log::warn(const char *fmt, ...)
     {
-        std::lock_guard<std::mutex> lock(mutexDebug);
+        std::lock_guard<std::mutex> lock(mutexLog);
         va_list args;
         va_start(args, fmt);
         fputs("Warning: ", stdout);
@@ -32,7 +31,7 @@ namespace odhtdb
     
     void Log::error(const char *fmt, ...)
     {
-        std::lock_guard<std::mutex> lock(mutexDebug);
+        std::lock_guard<std::mutex> lock(mutexLog);
         va_list args;
         va_start(args, fmt);
         fputs("Error: ", stderr);
diff --git a/src/OwnedMemory.cpp b/src/OwnedMemory.cpp
new file mode 100644
index 0000000..1d53faf
--- /dev/null
+++ b/src/OwnedMemory.cpp
@@ -0,0 +1,21 @@
+#include "../include/odhtdb/OwnedMemory.hpp"
+#include <cstdlib>
+
+namespace odhtdb
+{
+    OwnedMemory::OwnedMemory(OwnedMemory &&other)
+    {
+        data = other.data;
+        size = other.size;
+        
+        other.data = nullptr;
+        other.size = 0;
+    }
+    
+    OwnedMemory::~OwnedMemory()
+    {
+        free(data);
+        data = nullptr;
+        size = 0;
+    }
+}
diff --git a/src/PasswordHash.cpp b/src/PasswordHash.cpp
new file mode 100644
index 0000000..f6d3713
--- /dev/null
+++ b/src/PasswordHash.cpp
@@ -0,0 +1,23 @@
+#include "../include/odhtdb/PasswordHash.hpp"
+#include <argon2.h>
+
+namespace odhtdb
+{
+    OwnedMemory hashPassword(const DataView &plainPassword, const DataView &salt)
+    {
+        OwnedMemory result;
+        
+        const uint32_t tCost = 2;
+        const uint32_t mCost = 1 << 16;
+        const uint32_t parallelism = 1;
+        const uint32_t HASHLEN = 32;
+        
+        result.data = new uint8_t[HASHLEN];
+        result.size = HASHLEN;
+        
+        if(argon2i_hash_raw(tCost, mCost, parallelism, plainPassword.data, plainPassword.size, salt.data, salt.size, result.data, HASHLEN) != ARGON2_OK)
+            throw std::runtime_error("Failed to hash password");
+        
+        return result;
+    }
+}
diff --git a/src/Permission.cpp b/src/Permission.cpp
index 57c1f11..dc1e9b6 100644
--- a/src/Permission.cpp
+++ b/src/Permission.cpp
@@ -2,6 +2,13 @@
 
 namespace odhtdb
 {
+    Permission::Permission(u8 _permissionLevel, u32 _permissionFlags) : 
+        permissionLevel(_permissionLevel),
+        permissionFlags(_permissionFlags)
+    {
+        
+    }
+    
     Permission::Permission(u8 _permissionLevel, std::initializer_list<PermissionType> permissions) : 
         permissionLevel(_permissionLevel)
     {
diff --git a/src/Signature.cpp b/src/Signature.cpp
index b6fb12a..3fd52ee 100644
--- a/src/Signature.cpp
+++ b/src/Signature.cpp
@@ -64,6 +64,8 @@ namespace odhtdb
             return bin2hex(data, PUBLIC_KEY_NUM_BYTES);
         }
         
+        PrivateKey PrivateKey::ZERO("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", PRIVATE_KEY_NUM_BYTES);
+        
         PrivateKey::PrivateKey(const char *_data, size_t size)
         {
             if(size != PRIVATE_KEY_NUM_BYTES)
@@ -113,5 +115,12 @@ namespace odhtdb
             if(crypto_sign_ed25519_keypair((unsigned char*)publicKey.data, (unsigned char*)privateKey.data) < 0)
                 throw SignatureGenerationException("Failed to generate signature keypair");
         }
+        
+        KeyPair::KeyPair(const PublicKey &_publicKey, const PrivateKey &_privateKey) : 
+            publicKey(_publicKey),
+            privateKey(_privateKey)
+        {
+            
+        }
     }
 }
diff --git a/src/User.cpp b/src/User.cpp
index 7b90872..1fb4a11 100644
--- a/src/User.cpp
+++ b/src/User.cpp
@@ -3,7 +3,7 @@
 
 namespace odhtdb
 {
-    User::User(const std::string &_name, Group *group) : name(_name)
+    User::User(Type _type, const std::string &_name, Group *group) : type(_type), name(_name)
     {
         if(name.size() > 255)
             throw UserNameTooLongException(name);