diff --git a/src/Qt-RSA/qrsaencryption.cpp b/src/Qt-RSA/qrsaencryption.cpp
index d2e43cb..cf55d8f 100644
--- a/src/Qt-RSA/qrsaencryption.cpp
+++ b/src/Qt-RSA/qrsaencryption.cpp
@@ -292,8 +292,8 @@ QByteArray decodeArray(const QByteArray &rawData, const QByteArray &privKey) {
 QRSAEncryption::QRSAEncryption() {
 }
 
-unsigned int QRSAEncryption::getBytesSize(QRSAEncryption::Rsa rsa) {
-    return rsa / 8;
+unsigned int QRSAEncryption::getKeyBytesSize(QRSAEncryption::Rsa rsa) {
+    return rsa / 4;
 }
 
 // --- static methods ---
@@ -423,3 +423,7 @@ bool QRSAEncryption::testKeyPair(const QByteArray &pubKey, const QByteArray &pri
 
     return result;
 }
+
+bool QRSAEncryption::isValidRsaKey(const QByteArray &key) {
+    return key.size() && key.size() % RSA_64 == 0;
+}
diff --git a/src/Qt-RSA/qrsaencryption.h b/src/Qt-RSA/qrsaencryption.h
index 0beef87..b78ac70 100644
--- a/src/Qt-RSA/qrsaencryption.h
+++ b/src/Qt-RSA/qrsaencryption.h
@@ -34,7 +34,7 @@ public:
 
     QRSAEncryption();
 
-    unsigned int getBytesSize(QRSAEncryption::Rsa rsa);
+
 
 // static methods
     static bool generatePairKeyS(QByteArray &pubKey, QByteArray &privKey,
@@ -43,6 +43,8 @@ public:
     static QByteArray decodeS(const QByteArray &rawData, const QByteArray &privKey);
     static QByteArray signMessageS(QByteArray rawData, const QByteArray &privKey);
     static bool checkSignMessageS(const QByteArray &rawData, const QByteArray &pubKey);
+    static bool isValidRsaKey(const QByteArray& key);
+    static unsigned int getKeyBytesSize(QRSAEncryption::Rsa rsa);
 
 // non-static methods
     bool generatePairKey(QByteArray &pubKey, QByteArray &privKey,
@@ -52,6 +54,7 @@ public:
     QByteArray signMessage(QByteArray rawData, const QByteArray &privKey);
     bool checkSignMessage(const QByteArray &rawData, const QByteArray &pubKey);
 
+
 private:
     bool testKeyPair(const QByteArray &pubKey, const QByteArray &privKey);
 };