Method and system for maintaining secure data input and output

Abstract

Methods and systems for enhancing the security of data during input and output on a client computer system are provided to prevent attempts by unauthorized code to access, intercept, and/or modify data. Example embodiments provide a plurality of obfuscation techniques and security enhanced drivers that use these obfuscation techniques to prohibit unauthorized viewing/receiving of valid data. When the drivers are used together with the various obfuscation techniques, the security enhanced drivers provide mechanisms for “scheduling” the content of the storage areas used to store the data so that valid data is not available to unauthorized recipients. When unauthorized recipients attempt to access the “data,” they perceive or receive obfuscated data. The obfuscation techniques described include “copy-in,” “replace and restore,” and “in-place replacement” de-obfuscation/re-obfuscation techniques. In one embodiment, a security enhanced display driver, a security enhanced mouse driver, a security enhanced keyboard driver, and a security enhanced audio driver are provided. To complement the security enhancements, the methods and systems also provide for a watchdog mechanism to ensure that the driver is functioning as it should be and various user interface techniques for denoting security on a display device.

1 . A method in a computer system for providing a secure display area on a video display device of a video display system, the video display system having video display memory for storing data to be displayed on the video display device, comprising: 
 reserving a portion of the video display memory for secure data storage that corresponds to the secure display area;    receiving a request to display valid data in the secure display area, the request including an indication of the valid data;    storing the indicated valid data in a secure data buffer; and    storing invalid data in the reserved portion of the video display memory until a determined period of time before the data stored in the reserved portion is transferred to the video display device for display.    
   
   
       2 . The method of  claim 1 , further comprising: 
 at the beginning of the determined period of time, replacing the invalid data stored in the reserved portion of the video display memory with valid data from the secure data buffer.    
   
   
       3 . The method of  claim 2 , further comprising: 
 after the data stored in the reserved portion is transferred to the video display, re-storing the invalid data in the reserved portion of the video display memory.    
   
   
       4 . The method of  claim 1  wherein the secure data buffer is implemented by storing the valid data in the reserved portion of the video display memory as encrypted data.  
   
   
       5 . The method of  claim 1 , the video display memory having a frame buffer that stores data that is to be displayed on the video display device, wherein the secure data buffer is a portion of the frame buffer.  
   
   
       6 . The method of  claim 5  wherein the valid data is obfuscated prior to storing in the secure data buffer.  
   
   
       7 . The method of  claim 1  wherein the valid data is obfuscated prior to storing in the secure data buffer.  
   
   
       8 . The method of  claim 7  wherein obfuscation is performed by at least one of encryption of the valid data and a raster operation applied to the valid data and a mask.  
   
   
       9 . The method of  claim 8  wherein the mask is a bitmap comprising at least one of an encryption key, a company logo, a pattern, an advertisement, and a black region.  
   
   
       10 . The method of  claim 1  wherein the secure data buffer is one of an area in the video display memory, a portion of random access memory in the computer system, a secondary memory that resides on a video card that controls the video display device and storage accessible by other means.  
   
   
       11 . The method of  claim 10  wherein the secure data buffer is located in the reserved portion of video memory while the valid data is being displayed.  
   
   
       12 . The method of  claim 10  wherein the location of the secure data buffer is one of a user designated, application designated, and system designated location.  
   
   
       13 . A secure video display driver for providing a secure display area on a video display device of a video display system, the video display system having video display memory for storing data to be displayed on the video display device, comprising: 
 a data receiver that is structured to receive a request to display valid data in the secure display area, the request including an indication of the valid data; and    a video display memory scheduler that is structured to: 
 reserve a portion of the video display memory for secure data storage that corresponds to the secure display area;  
 store the indicated valid data in a secure data buffer; and  
 store invalid data in the reserved portion of the video display memory until a determined period of time before the data stored in the reserved portion is transferred to the video display device for display.  
   
   
   
       14 . The display driver of  claim 13  wherein the video display memory scheduler is further structured to: 
 at the beginning of the determined period of time, replace the invalid data stored in the reserved portion of the video display memory with valid data from the secure data buffer.    
   
   
       15 . The display driver of  claim 14 , wherein the video display memory scheduler is further structured to: 
 after the data stored in the reserved portion is transferred to the video display, store invalid data in the reserved portion of the video display memory.    
   
   
       16 . The display driver of  claim 13  wherein the secure data buffer is implemented by storing the valid data in the reserved portion of the video display memory as encrypted data.  
   
   
       17 . The display driver of  claim 13  wherein the secure data buffer is one of an area in the video display memory, a portion of random access memory in the computer system, a secondary memory that resides on a video card that controls the video display device and storage accessible by other means.  
   
   
       18 . The display driver of  claim 13  wherein the secure data buffer location is one of a user designated, application designated, and system designated location.  
   
   
       19 . The display driver of  claim 13 , the video display memory having a frame buffer that stores data that is to be displayed on the video display device, wherein the secure data buffer is a portion of the frame buffer.  
   
   
       20 . The display driver of  claim 13  wherein the valid data is obfuscated prior to storing in the secure data buffer.  
   
   
       21 . A computer-readable memory medium containing instructions for controlling a computer processor to provide a secure display area on a video display device of a video display system, the video display system having video display memory for storing data to be displayed on the video display device, by: 
 reserving a portion of the video display memory for secure data storage that corresponds to the secure display area;    receiving a request to display valid data in the secure display area, the request including an indication of the valid data;    storing the indicated valid data in a secure data buffer; and    storing invalid data in the reserved portion of the video display memory until a determined period of time before the data stored in the reserved portion is transferred to the video display device for display.    
   
   
       22 . A method in a computer system for ensuring the secure receipt of input from an input data device, the computer system having a system input device driver code and an ordering of device driver codes such that a first device driver code gains control before other device driver codes, comprising: 
 installing a modified input driver code as the first device driver code, thereby insuring that the system input device driver code does not process an input event first; and    under control of the modified input driver code, 
 receiving an input event;  
 determining whether the input event is designated as a secure input event; and  
 when it is determined that the input event is a secure input event, processing the input event.  
   
   
   
       23 . The method of  claim 22 , further comprising: 
 forwarding the input event to the system input event device driver code when it is determined that the input event is not a secure input event.    
   
   
       24 . The method of  claim 22  wherein the input device driver code controls a pointing device.  
   
   
       25 . The method of  claim 22  wherein the input device driver code controls a keyboard device.  
   
   
       26 . The method of  claim 22  wherein the input device driver code is responsive to an audio device.  
   
   
       27 . The method of  claim 22  wherein processing the input event comprises passing the input event to a recipient authorized to receive the secure input event.