Random bit mask generation for obscuring data on nonvolatile memory device

Abstract

A method and apparatus for preventing unauthorized access to information temporarily stored in memory, such as a hard disk drive, associated with a digital document processor, such as a digital copier, printer, or facsimile machine. This invention includes storing information to memory, conducting an operation on the information, and automatically overwriting the information one or more times with a bit mask. Bit masks may be non-random or random sequences of binary values.

What is claimed is:  
     
         1 . A method for concealing information stored in at least one memory, said method comprising the steps of: 
 (a) storing information to said at least one memory;    (b) conducting an operation on said information stored in said at least one memory; and    (c) automatically overwriting said information by storing a bit mask to said at least one memory.    
     
     
         2 . The method of    claim 1   , wherein said step of storing information further comprises a step selected from the group consisting of: 
 (a) storing said information to a photocopier memory;    (b) storing said information to a printer memory;    (c) storing said information to a document scanner memory;    (d) storing said information to a facsimile machine memory;    (e) storing said information to a computer memory;    (f) storing said information to a personal digital assistant memory;    (g) storing said information to a cellular telephone memory; and    (h) storing said information to a digital camera memory.    
     
     
         3 . The method according to    claim 1   , wherein said step of storing information further comprises a step of storing information to a nonvolatile memory.  
     
     
         4 . The method according to    claim 1   , wherein said step of storing information further comprises a step of storing information to a plurality of memories.  
     
     
         5 . The method of    claim 1   , wherein said step of conducting an operation further comprises a step selected from the group consisting of: 
 (a) printing said information;    (b) copying said information;    (c) scanning said information;    (d) deleting said information;    (e) storing said information;    (f) modifying said information;    (g) transmitting said information;    (h) reading said information;    (i) writing said information; and    (j) viewing said information.    
     
     
         6 . The method of    claim 1   , wherein said step of automatically overwriting information further comprises a step selected from the group consisting of: 
 (a) automatically overwriting said information with a pseudo-randomly generated bit mask;    (b) automatically overwriting said information with a randomly generated bit mask;    (c) automatically overwriting said information with a predetermined bit mask;    (d) automatically overwriting said information with a sequence of binary ones;    (e) automatically overwriting said information with a sequence of binary zeros;    (f) automatically overwriting said information with a predetermined sequence of binary numbers;    (g) automatically overwriting said information at least twice;    (h) automatically overwriting said information to a plurality of memories;    (i) automatically overwriting said information with a positive polarity;    (j) automatically overwriting said information with a negative polarity; and    (k) automatically overwriting said information with a combination of overwriting schemes.    
     
     
         7 . An apparatus for concealing information stored in at least one memory, comprising: 
 (a) said at least one memory for storing information; and    (b) a processor for conducting at least one operation on said information;    (c) means for concealing information automatically after said at least one operation.    
     
     
         8 . The apparatus of    claim 7   , wherein said at least one memory is selected from the group consisting of: 
 (a) a photocopier memory;    (b) a printer memory;    (c) a document scanner memory;    (d) a facsimile machine memory;    (e) a computer memory;    (f) a personal digital assistant memory;    (g) a cellular telephone memory; and    (h) a digital camera memory.    
     
     
         9 . The apparatus of    claim 7   , wherein said at least one operation is selected from the group consisting of: 
 (a) printing said information;    (b) copying said information;    (c) scanning said information;    (d) deleting said information;    (e) storing said information;    (f) modifying said information;    (g) transmitting said information;    (h) reading said information;    (i) writing said information;    (j) overwriting said information; and    (k) viewing said information.    
     
     
         10 . The apparatus of    claim 7   , wherein said means for concealing information is selected from the group consisting of 
 (a) automatically overwriting said information with a pseudo-randomly generated bit mask;    (b) automatically overwriting said information with a randomly generated bit mask;    (c) automatically overwriting said information with a predetermined bit mask;    (d) automatically overwriting said information with a sequence of binary ones;    (e) automatically overwriting said information with a sequence of binary zeros;    (f) automatically overwriting said information with a predetermined sequence of binary numbers;    (g) automatically overwriting said information at least twice;    (h) automatically overwriting said information to a plurality of memories;    (i) automatically overwriting said information with a positive polarity;    (j) automatically overwriting said information with a negative polarity; and    (k) automatically overwriting said information with a combination of overwriting schemes.    
     
     
         11 . The apparatus of    claim 7    further comprising a plurality of memories.