A keystroke authentication method has a relatively low cost, yet it is more powerful and easier to use than other biometric authentication methods. However, traditional keystroke authentication has many weaknesses and is easily exploited by malicious actors. Malicious attacks can include shoulder surfing attacks, eavesdropping attacks and key-logger attacks. When users try to access their computer or portable device by using a keystroke authentication method, the users must push the correct buttons with the correct rhythm in order to be authenticated. ...