Patent Publication Number: US-8973107-B2

Title: Method and apparatus for securing keystrokes from being intercepted between the keyboard and a browser

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/048,816, filed Oct. 8, 2013, currently pending, which is a continuation of U.S. patent application Ser. No. 11/656,236, filed Jan. 22, 2007, now U.S. Pat. No. 8,566,608, which claims the benefit of U.S. Provisional Patent Application No. 60/765,141, filed on Feb. 2, 2006. The disclosures of all of the above applications are hereby incorporated by reference in their entireties into the present disclosure. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to computer security and, more particularly, to a method and apparatus of encrypting keystrokes, entered on a computer keyboard, before they are processed by a browser so that resident keyloggers cannot capture them. 
     2. Description of the Related Art 
     What is a Keylogger? 
     A Keylogger is a software program that runs in the background, recording all the keystrokes. Once keystrokes are logged, they are hidden in the machine for later retrieval, or shipped raw to the attacker. The attacker then peruses them carefully in the hopes of either finding passwords, or possibly other useful information such as credit card numbers, social security numbers or any other information used to commit identity theft. 
     A keyloggers can enter a user&#39;s computer in the following ways—(1) They can be embedded in images and music files which the user downloads when they click on pictures or mp3 files. (2) They can be downloaded inadvertently when a user browses a malicious web site. (3) They can be embedded in a virus, spyware or Trojan horse. (4) They can be bundled as a part of software that a user downloads for free. 
     How Keyloggers Work 
     When a user presses a key on the keyboard, the keyboard device driver receives scan codes from the keyboard, which are sent to the keyboard layout where they are translated into messages and posted to the appropriate window in the application. Assigned to each key on a keyboard is a unique value called a scan code, a device-dependent identifier for the key on the keyboard. A keyboard generates two scan codes when the user types a key—one when the user presses the key and another when the user releases the key. 
     The keyboard device driver interprets a scan code and translates it to a virtual-key code, a device-independent value defined by the system that identifies the purpose of a key. After translating a scan code, the keyboard driver creates a message that includes the scan code, the virtual-key code, and other information about the keystroke, and then places the message in the system message queue. The system removes the message from the system message queue and posts it to the message queue of the appropriate thread of the application. Eventually, the thread&#39;s message loop removes the message and passes it to the appropriate window procedure of the application for processing. 
     A keylogger can intercept the keystroke at any point in the chain. It can intercept it in any of following ways—(1) the keyboard driver level—by replacing the keyboard driver with a rogue driver, (2) by adding filters between the keyboard driver and the system message queue. The filter receives keystrokes from the keyboard driver before it is sent to the message queue. and (3) the system message queue level—by hooking into the Windows message queue. A hook is a callback function provided by the keylogger to the system. When a keystroke message arrives in the message queue, the callback function associated with the keylogger is called and it is passed the keystroke information. The keylogger then stores the keystroke data in a file which is later sent to the hacker via an email, an IRC channel or some other means. 
     Current State-of-the Art in Anti-Keylogging 
     Currently, there are two ways to stopping keyloggers—(1) detecting them and (2) preventing them from hooking the keystroke messages. 
     Keyloggers can be detected by analyzing their signatures. Signatures comprise the characteristics of the keylogger such as file size, file name, a checksum, or registry entries. The drawback of this method is that the signatures need to be constantly updated and is not effective against unknown keyloggers. 
     Keyloggers can be prevented from hooking the keystroke messages by placing a hook before the keylogger&#39;s hook and preventing the keystroke messages from going to the keylogger. The drawback of this method is that there is no way to guarantee that a hook can be placed before the keylogger&#39;s hook. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention foils a keylogger by a novel way—creating a custom keyboard driver and passing the keystrokes directly to the browser in an encrypted format. The browser (which is used to access the Internet) has a component (a Browser Helper Object) that decrypts the keystroke before it is sent to the website. Thus, the present invention enables the user to go to any website and enter sensitive information (passwords, credit card numbers, etc.) without the keystrokes being intercepted by Keyloggers. 
     In general terms, the invention described herein provides a method and apparatus for modifying the keyboard driver, encrypting the keystrokes between the keyboard driver and a browser component, and putting the decrypted keystrokes into the browser. Also, the invention has a mechanism to detect if its operation is foiled and make the user aware that the protection mechanism has been compromised. 
     OBJECT AND FEATURES OF THE INVENTION 
     In accordance with a first aspect of the invention, the invention features a methodology for taking control of the keyboard at the hardware level via a proprietary keyboard driver, encrypt the keystrokes and send them the browser, where they are decrypted. 
     In accordance with a second aspect of the invention, the invention features a methodology to detect if its operation is foiled and make the user aware that the protection mechanism has been compromised. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  depicts the methodology to process keystrokes that exists today. 
         FIG. 2  depicts the novel methodology to process keystrokes that is proposed by this invention. 
         FIG. 3  depicts the Proprietary Device Driver. 
         FIG. 4  depicts the Browser Component. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Exemplary embodiments of the invention are described herein in terms of processes. Efficient prototypes of such processes have been implemented as computer system software on general-purpose PC hardware. 
     In accordance with a first aspect of the invention, the invention features a methodology for taking control of the keyboard at the hardware level via a proprietary keyboard driver, encrypt the keystrokes and send them the browser, where they are decrypted. 
       FIG. 1  depicts the methodology to process keystrokes that exists today. When a key is pressed on the Keyboard  101 , an interrupt is generated which is sent to the Interrupt Controller  102 . The Interrupt Controller  102  goes to a specific location in the Interrupt Device Table  103  which contains the address of the Keyboard Device Driver  104  which will process the interrupt. The Keyboard Device Driver  104  retrieves the keystroke scan code, converts the scan code to virtual-key code, creates a message that includes the scan code, the virtual-key code, and other information about the keystroke, and sends it to the System Message Queue  105 . The message is retrieved by the Browser  106  which displays the keystroke. 
       FIG. 2  depicts the novel methodology to process keystrokes that is proposed by this invention. The components that implement the invention are the Proprietary Device Driver  107  and the Browser Component  108 . When the Browser  106  has focus, the Browser Component  108  sends a message to the Proprietary Device Driver  107  to modify the Interrupt Device Table  103  to point to the Proprietary Device Driver  107  for handling keyboard interrupts. 
     When a key is pressed on the Keyboard  101 , an interrupt is generated which is sent to the Interrupt Controller  102 . The Interrupt Controller  102  goes to a specific location in the Interrupt Device Table  103  which contains the address of the Proprietary Device Driver  107  which will process the interrupt. The Proprietary Device Driver  107  retrieves the keystroke scan code, converts the scan code to virtual-key code, creates a message that includes the scan code, the virtual-key code, and other information about the keystroke, encrypts the message and sends it to the Browser Component  108 . The Browser Component  108  decrypts the message and sends it to the Browser  106  which displays the keystroke. 
       FIG. 3  depicts the Proprietary Device Driver. It consists of (1) the EDT Interface  109  which communicates with the system to make changes to the Interrupt Device Table  103  ( FIG. 1 ), (2) the Keyboard Device Driver  110  which retrieves the keystroke entered by the user, and (3) the Keystroke Encrypter  111  which encrypts the keystroke scan code and the virtual-key code, and (4) the Browser Component Interface  112  which communicates with the Browser Component  108  ( FIG. 2 ). 
       FIG. 4  depicts the Browser Component. It consists of (1) the Proprietary Device Driver Interface  113  which communicates with the Proprietary Device Driver  107  ( FIG. 2 ), (2) the Keystroke Decrypter  114  which decrypts the encrypted scan code and the virtual-key code, and (3) The Browser Interface  115  which sends the decrypted keystroke message to the Browser  106  ( FIG. 1 ). 
     In accordance with a second aspect of the invention, the invention features a methodology to detect if its operation is foiled and make the user aware that the protection mechanism has been compromised. 
     Referring to  FIG. 2 , when the Browser  106  has focus, the Browser Component  108  sends a message to the Proprietary Device Driver  107  to modify the Interrupt Device Table  103  to point to the Proprietary Device Driver  107  for handling keyboard interrupts. If the Proprietary Device Driver  107  is unable to modify the Interrupt Device Table  103 , it realizes that the system has been compromised by a hacker and displays a message to the user that the system has been compromised.