diff --git a/src/core/Tools.cpp b/src/core/Tools.cpp
index 6811d078..33f2fee2 100644
--- a/src/core/Tools.cpp
+++ b/src/core/Tools.cpp
@@ -53,6 +53,22 @@ bool hasChild(const QObject* parent, const QObject* child)
     return false;
 }
 
+bool readFromDevice(QIODevice* device, QByteArray& data, int size)
+{
+    QByteArray buffer;
+    buffer.resize(size);
+
+    qint64 readResult = device->read(buffer.data(), size);
+    if (readResult == -1) {
+        return false;
+    }
+    else {
+        buffer.resize(readResult);
+        data = buffer;
+        return true;
+    }
+}
+
 bool readAllFromDevice(QIODevice* device, QByteArray& data)
 {
     QByteArray result;
diff --git a/src/core/Tools.h b/src/core/Tools.h
index 65c0f5e2..e5188d17 100644
--- a/src/core/Tools.h
+++ b/src/core/Tools.h
@@ -28,6 +28,7 @@ namespace Tools {
 
 QString humanReadableFileSize(qint64 bytes);
 bool hasChild(const QObject* parent, const QObject* child);
+bool readFromDevice(QIODevice* device, QByteArray& data, int size = 16384);
 bool readAllFromDevice(QIODevice* device, QByteArray& data);
 QDateTime currentDateTimeUtc();
 QString imageReaderFilter();
diff --git a/src/crypto/CryptoHash.cpp b/src/crypto/CryptoHash.cpp
index 31c0c934..c9459598 100644
--- a/src/crypto/CryptoHash.cpp
+++ b/src/crypto/CryptoHash.cpp
@@ -66,6 +66,10 @@ void CryptoHash::addData(const QByteArray& data)
 {
     Q_D(CryptoHash);
 
+    if (data.isEmpty()) {
+        return;
+    }
+
     gcry_md_write(d->ctx, data.constData(), data.size());
 }
 
diff --git a/src/keys/FileKey.cpp b/src/keys/FileKey.cpp
index 9063251d..b22c5b0f 100644
--- a/src/keys/FileKey.cpp
+++ b/src/keys/FileKey.cpp
@@ -222,8 +222,14 @@ bool FileKey::loadBinary(QIODevice* device)
         return false;
     }
 
-    m_key = device->readAll();
-    return true;
+    QByteArray data;
+    if (!Tools::readAllFromDevice(device, data) || data.size() != 32) {
+        return false;
+    }
+    else {
+        m_key = data;
+        return true;
+    }
 }
 
 bool FileKey::loadHex(QIODevice* device)
@@ -232,7 +238,10 @@ bool FileKey::loadHex(QIODevice* device)
         return false;
     }
 
-    QByteArray data = device->readAll();
+    QByteArray data;
+    if (!Tools::readAllFromDevice(device, data) || data.size() != 64) {
+        return false;
+    }
 
     if (!Tools::isHex(data)) {
         return false;
@@ -253,11 +262,12 @@ bool FileKey::loadHashed(QIODevice* device)
     CryptoHash cryptoHash(CryptoHash::Sha256);
 
     QByteArray buffer;
-
-    while (!device->atEnd()) {
-        buffer = device->read(1024);
+    do {
+        if (!Tools::readFromDevice(device, buffer)) {
+            return false;
+        }
         cryptoHash.addData(buffer);
-    }
+    } while (!buffer.isEmpty());
 
     m_key = cryptoHash.result();