QByteArray string = "Nokia";
QCryptographicHash hasher(QCryptographicHash::Sha1);
hasher.addData(string);

QByteArray string1=hasher.result();

#include <QtGui/QApplication>
#include <QWidget>
#include <QHBoxLayout>
#include <QCryptographicHash>
#include <QString>
#include <QByteArray>
#include <QLineEdit>
#include <QLabel>
#include <QGridLayout>
#include <QPushButton>
#include <QHBoxLayout>
 
int main(int argc, char **argv){
	QApplication app(argc, argv);
 
	QWidget mainWindow;
	QGridLayout* layout=new QGridLayout();
 
	//widget initialization
	QLineEdit *hashTextEdit=new QLineEdit(),
		*originalTextEdit = new QLineEdit();
	originalTextEdit->setReadOnly(true);
	originalTextEdit->setText(QObject::tr("Nokia"));
	hashTextEdit->setReadOnly(true);
	QLabel *hashLabel=new QLabel(QObject::tr("MD4 &Hash:")),
		*originalTextLabel = new QLabel(QObject::tr("Original &Text:"));
	hashLabel->setBuddy(hashTextEdit);
	originalTextLabel->setBuddy(originalTextEdit);
 
	//widget placement
	layout->addWidget(originalTextLabel, 0, 0);
	layout->addWidget(originalTextEdit, 0, 1);
	layout->addWidget(hashLabel, 1, 0);
	layout->addWidget(hashTextEdit, 1, 1);
 
	//bottom layout initialization ("close" button)
	QHBoxLayout* bottomLayout = new QHBoxLayout();
	bottomLayout->addStretch();
	QPushButton* closeButton = new QPushButton(QObject::tr("C&lose"));
	bottomLayout->addWidget(closeButton);
	bottomLayout->addStretch();
	bottomLayout->setMargin(0);
 
	layout->addLayout(bottomLayout, 2, 0, 1, 2);
 
	QObject::connect(closeButton, SIGNAL(clicked()), &mainWindow, SLOT(close()));
 
	mainWindow.setLayout(layout);
 
	//actual hash calculation TODO: make proper widget with signal/slots for hash calculation
	QCryptographicHash hash(QCryptographicHash::Md4);
	hash.addData(originalTextEdit->text().toUtf8());
	hashTextEdit->setText(QString(hash.result().toHex()));
 
	mainWindow.showMaximized();
 
	return app.exec();
}