Abstract:
An approach for improving input/output control and efficiency in an encrypted file system (EFS) is provided. In this approach, a software application writes data to a first buffer and then requests that an encrypted file system save the data onto a nonvolatile storage device. The encrypted file system encrypts the data and stores the encrypted data in a second buffer and then writes the encrypted data from the second buffer to the nonvolatile storage area. Meanwhile, the software application is able to resume writing additional data to the buffer after the data has been copied to the second buffer even if the data has not yet been written to the nonvolatile storage area.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to an approach for improving the input/output control and efficiency in an encrypted file system. More particularly, the present invention provides an approach that reduces the time that an application has to wait while storing data in an encrypted file system. 
     2. Description of the Related Art 
     Encrypted file systems include “full disk encryption” (also known as “whole disk encryption”) as well as filesystem-level encryption (also known as “folder encryption). As the name implies, in full disk encryption, nearly every file is encrypted including swap files and temporary files. Because nearly everything is encrypted, the user typically cannot decide which files to encrypt. On the other hand, filesystem level encryption is a form of disk encryption where individual files, directories (folders), or the file system itself are encrypted. Typically, filesystem level encryption is more flexible, especially in terms of the encryption keys used to encrypt the files and directories. Generally, file system metadata (e.g., directory structures, files names, etc.) are not encrypted with filesystem level encryption, while this metadata is traditionally encrypted under full disk encryption. Regardless of the particular type of encrypted file system, encrypted file systems are challenged in terms of input/output control as well as efficiency. 
     Encrypted file systems employ encryption algorithms to encrypt unencrypted data into an encrypted format before storing the encrypted data onto a nonvolatile storage device, such as a hard drive. Encrypting data into an encrypted format and then writing the encrypted data to the nonvolatile storage device is relatively time consuming. One challenge is that the software application waits for the encrypted file system to encrypt and store data before proceeding. This results in decreased efficiency in terms of both the encrypted file system as well as the software applications running in a system that uses an encrypted file system. 
     SUMMARY 
     It has been discovered that the aforementioned challenges are resolved using an approach where a software application writes data to a first buffer and then requests that an encrypted file system save the data onto a nonvolatile storage device. The encrypted file system encrypts the data and stores the encrypted data in a second buffer and then writes the encrypted data from the second buffer to the nonvolatile storage area. Meanwhile, the software application is able to resume writing additional data to the buffer after the data has been copied to the second buffer even if the data has not yet been written to the nonvolatile storage area. 
     writing, by the software application, a second set of data to the first buffer, wherein the second set of data is written to the first buffer before the encrypted file system has completed writing the first set of encrypted data to the nonvolatile storage area. 
     The foregoing is a summary and thus contains, by necessity, simplifications, generalizations, and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the present invention, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings, wherein: 
         FIG. 1  is a block diagram of a data processing system in which the methods described herein can be implemented; 
         FIG. 2  provides an extension of the information handling system environment shown in  FIG. 1  to illustrate that the methods described herein can be performed on a wide variety of information handling systems which operate in a networked environment; 
         FIG. 3  is a diagram of the interface between an application and an encrypted file system in order to securely save the application&#39;s data in the encrypted file system; and 
         FIG. 4  is a flowchart showing the application saving its data using the encrypted file system so that the application does not have to wait to write new data while the encrypted file system is busy encrypting data. 
     
    
    
     DETAILED DESCRIPTION 
     Certain specific details are set forth in the following description and figures to provide a thorough understanding of various embodiments of the invention. Certain well-known details often associated with computing and software technology are not set forth in the following disclosure, however, to avoid unnecessarily obscuring the various embodiments of the invention. Further, those of ordinary skill in the relevant art will understand that they can practice other embodiments of the invention without one or more of the details described below. Finally, while various methods are described with reference to steps and sequences in the following disclosure, the description as such is for providing a clear implementation of embodiments of the invention, and the steps and sequences of steps should not be taken as required to practice this invention. Instead, the following is intended to provide a detailed description of an example of the invention and should not be taken to be limiting of the invention itself. Rather, any number of variations may fall within the scope of the invention, which is defined by the claims that follow the description. 
     The following detailed description will generally follow the summary of the invention, as set forth above, further explaining and expanding the definitions of the various aspects and embodiments of the invention as necessary. To this end, this detailed description first sets forth a computing environment in  FIG. 1  that is suitable to implement the software and/or hardware techniques associated with the invention. A networked environment is illustrated in  FIG. 2  as an extension of the basic computing environment, to emphasize that modern computing techniques can be performed across multiple discrete devices. 
       FIG. 1  illustrates information handling system  100  which is a simplified example of a computer system capable of performing the computing operations described herein. Information handling system  100  includes one or more processors  110  which is coupled to processor interface bus  112 . Processor interface bus  112  connects processors  110  to Northbridge  115 , which is also known as the Memory Controller Hub (MCH). Northbridge  115  is connected to system memory  120  and provides a means for processor(s)  110  to access the system memory. Graphics controller  125  is also connected to Northbridge  115 . In one embodiment, PCI Express bus  118  is used to connect Northbridge  115  to graphics controller  125 . Graphics controller  125  is connected to display device  130 , such as a computer monitor. 
     Northbridge  115  and Southbridge  135  are connected to each other using bus  119 . In one embodiment, the bus is a Direct Media Interface (DMI) bus that transfers data at high speeds in each direction between Northbridge  115  and Southbridge  135 . In another embodiment, a Peripheral Component Interconnect (PCI) bus is used to connect the Northbridge and the Southbridge. Southbridge  135 , also known as the I/O Controller Hub (ICH) is a chip that generally implements capabilities that operate at slower speeds than the capabilities provided by the Northbridge. Southbridge  135  typically provides various busses used to connect various components. These busses can include PCI and PCI Express busses, an ISA bus, a System Management Bus (SMBus or SMB), a Low Pin Count (LPC) bus. The LPC bus is often used to connect low-bandwidth devices, such as boot ROM  196  and “legacy” I/O devices (using a “super I/O” chip). The “legacy” I/O devices ( 198 ) can include serial and parallel ports, keyboard, mouse, floppy disk controller. The LPC bus is also used to connect Southbridge  135  to Trusted Platform Module (TPM)  195 . Other components often included in Southbridge  135  include a Direct Memory Access (DMA) controller, a Programmable Interrupt Controller (PIC), a storage device controller, which connects Southbridge  135  to nonvolatile storage device  300  such as a hybrid hard disk drive, using bus  184 . 
     ExpressCard  155  is a slot used to connect hot-pluggable devices to the information handling system. ExpressCard  155  supports both PCI Express and USB connectivity as it is connected to Southbridge  135  using both the Universal Serial Bus (USB) the PCI Express bus. Southbridge  135  includes USB Controller  140  that provides USB connectivity to devices that connect to the USB. These devices include webcam (camera)  150 , infrared (IR) receiver  148 , Bluetooth device  146  which provides for wireless personal area networks (PANs), keyboard and trackpad  144 , and other miscellaneous USB connected devices  142 , such as a mouse, removable nonvolatile storage device  145 , modems, network cards, ISDN connectors, fax, printers, USB hubs, and many other types of USB connected devices. While removable nonvolatile storage device  145  is shown as a USB-connected device, removable nonvolatile storage device  145  could be connected using a different interface, such as a Firewire interface, etc. Removable storage device  145  can also be a hybrid disk drive, such as hybrid disk drive  300  shown in  FIGS. 3-6 . 
     Wireless Local Area Network (LAN) device  175  is connected to Southbridge  135  via the PCI or PCI Express bus  172 . LAN device  175  typically implements one of the IEEE 802.11 standards of over-the-air modulation techniques that all use the same protocol to wireless communicate between information handling system  100  and another computer system or device. Optical storage device  190  is connected to Southbridge  135  using Serial ATA (SATA) bus  188 . Serial ATA adapters and devices communicate over a high-speed serial link. The Serial ATA bus is also used to connect Southbridge  135  to other forms of storage devices, such as hard disk drives. Audio circuitry  160 , such as a sound card, is connected to Southbridge  135  via bus  158 . Audio circuitry  160  is used to provide functionality such as audio line-in and optical digital audio in port  162 , optical digital output and headphone jack  164 , internal speakers  166 , and internal microphone  168 . Ethernet controller  170  is connected to Southbridge  135  using a bus, such as the PCI or PCI Express bus. Ethernet controller  170  is used to connect information handling system  100  with a computer network, such as a Local Area Network (LAN), the Internet, and other public and private computer networks. 
     While  FIG. 1  shows one information handling system, an information handling system may take many forms. For example, an information handling system may take the form of a desktop, server, portable, laptop, notebook, or other form factor computer or data processing system. In addition, an information handling system may take other form factors such as a personal digital assistant (PDA), a gaming device, ATM machine, a portable telephone device, a communication device or other devices that include a processor and memory. 
     The Trusted Platform Module (TPM  195 ) shown in  FIG. 1  and described herein to provide security functions is but one example of a hardware security module (HSM). Therefore, the TPM described and claimed herein includes any type of HSM including, but not limited to, hardware security devices that conform to the Trusted Computing Groups (TCG) standard, and entitled “Trusted Platform Module (TPM) Specification Version 1.2.” The TPM is a hardware security subsystem that may be incorporated into any number of information handling systems, such as those outlined in  FIG. 2 . 
       FIG. 2  provides an extension of the information handling system environment shown in  FIG. 1  to illustrate that the methods described herein can be performed on a wide variety of information handling systems which operate in a networked environment. Types of information handling systems range from small handheld devices, such as handheld computer/mobile telephone  210  to large mainframe systems, such as mainframe computer  270 . Examples of handheld computer  210  include personal digital assistants (PDAs), personal entertainment devices, such as MP3 players, portable televisions, and compact disc players. Other examples of information handling systems include pen, or tablet, computer  220 , laptop, or notebook, computer  230 , workstation  240 , personal computer system  250 , and server  260 . Other types of information handling systems that are not individually shown in  FIG. 2  are represented by information handling system  280 . As shown, the various information handling systems can be networked together using computer network  200 . Types of computer network that can be used to interconnect the various information handling systems include Local Area Networks (LANs), Wireless Local Area Networks (WLANs), the Internet, the Public Switched Telephone Network (PSTN), other wireless networks, and any other network topology that can be used to interconnect the information handling systems. Many of the information handling system include nonvolatile data stores, such as hard drives and/or nonvolatile memory. Some of the information handling systems shown in  FIG. 2  are depicted with separate nonvolatile data stores (server  260  is shown with nonvolatile data store  265 , mainframe computer  270  is shown with nonvolatile data store  275 , and information handling system  280  is shown with nonvolatile data store  285 ). The nonvolatile data store can be a component that is external to the various information handling systems or can be internal to one of the information handling systems. In addition, removable nonvolatile storage device  145  can be shared amongst two or more information handling systems using various techniques, such as connecting the removable nonvolatile storage device  145  to a USB port or other connector of the information handling systems. 
       FIG. 3  is a diagram of the interface between an application and an encrypted file system in order to securely save the application&#39;s data in the encrypted file system. Application  300  writes data  310  to first buffer  320 . As shown, first buffer is used to store unencrypted data used by or generated by application  300 . At some point, such as when buffer  320  becomes full, a request is made to encrypted file system process  330  to write the data to the encrypted file system  375 . In one embodiment, the encrypted file system process is a kernel process that runs within a kernel of an operating system. 
     Encrypted file system process  330  reads the data from first buffer  320  and writes encrypted data  340  to second buffer  350 . In one embodiment, data is read from first buffer  320 , encrypted, and the resulting encrypted data  340  is stored in second buffer  350 . In an alternate embodiment, data is read from first buffer  320  and written to second buffer  350  and then encrypted in place in the second buffer. After encrypted data  340  has been created and stored in second buffer  350  (e.g., using one of the embodiments described above), then encrypted file system process  330  performs disk write  360  which results in the encrypted data being read from second buffer  350  and stored in nonvolatile data store  370  which is part of the encrypted file system. 
     Application  300  is allowed to write additional data to first buffer  320  after the data has been read from first buffer  320  by encrypted file system process  330 . In one embodiment, the encrypted file system process locks first buffer  320  upon receiving the request from application  300 . When encrypted file system process  330  is finished reading the data, it unlocks first buffer  320  so that application  300  can resume writing data to the first buffer. In this manner, application  300  can resume writing data to first buffer  300  before all of the encrypted data stored in second buffer  350  has been written to encrypted data store  370 . 
       FIG. 4  is a flowchart showing the application saving its data using the encrypted file system so that the application does not have to wait to write new data while the encrypted file system is busy encrypting data. The software application&#39;s processing commences at  300  whereupon, at step  410 , the software applications writes unencrypted data to first buffer  320  which is stored in the memory of the information handling system where the software application is running. At some point (e.g., when first buffer  320  is full or nearly full, etc.) a request is made to save the data that has been written to the buffer to the nonvolatile storage managed by the encrypted file system (step  420 ). In one embodiment, the request includes a pointer or address of first buffer  320  as well as any file characteristics (e.g., filename, file location, directory, etc.) where the data is to be stored in the encrypted file system. At step  425 , the software application waits to write additional data to first buffer  320  until the first buffer is unlocked by the encrypted file system process. 
     Encrypted file system processing (e.g., performed by an operating system kernel process) is shown commencing at  330  whereupon, at step  430 , the encrypted file system process receives the request to save data to nonvolatile storage. At step  440 , the encrypted file system either allocates or uses an existing second buffer that will be used to store the encrypted data. At step  450 , while the encrypted file system process is reading the data from first buffer  320 , the first buffer is locked so that the software application (or other software applications) will not be able to write data to the buffer while the encrypted file system process is reading the data. In a first embodiment, at step  460 , the unencrypted data is read from first buffer  320 , encrypted by the encrypted file system process, and the encrypted data is stored in second buffer  350 . In a second embodiment, at step  460 , the unencrypted data is read from first buffer  320 , written to second buffer  350 , and encrypted in place. While in a third embodiment, at step  460 , the unencrypted data is read from first buffer  320 , written to another buffer (a third buffer), and then the data in the third buffer is read and encrypted and the resulting encrypted data is stored in second buffer  350 . In any case, at step  470 , the encrypted file system process unlocks the first buffer after all of the data has been read from the first buffer. Using the first embodiment, the first buffer is unlocked once all of the data is read from first buffer  320  and the resulting encrypted data is written to second buffer  350 . Taking the second embodiment, the first buffer is unlocked when all of the unencrypted data has been read from first buffer  320  and written to second buffer  350  (i.e., before the encryption in-place has taken been performed). Finally, using the third embodiment, the first buffer is unlocked when all of the unencrypted data has been read from first buffer  320  and written to a “third” buffer (before the data is encrypted and saved to second buffer  350 ). 
     When first buffer  320  is unlocked, the software application is notified and, at step  475 , the software application can resume using first buffer  320  to read and write data without having to wait for the resulting encrypted data to actually be written to nonvolatile storage. Taking place at the same time as step  475 , the encrypted file system process, at step  480 , writes the encrypted data stored in second buffer  350  to nonvolatile storage  370  that is managed by the encrypted file system. As mentioned above, while the encrypted file system process is writing the encrypted data to data store  370 , the software application is free to resume writing data to first buffer  320  for eventual writing to the nonvolatile storage managed by the encrypted file system. At step  490 , after the encrypted data has been written to the nonvolatile storage, the second buffer is de-allocated (freed) in order to free the memory used to store the second buffer. Encrypted file system processing ends at  495  until the encrypted file system is requested by a software application to read or write more data to a nonvolatile storage area that is managed by the encrypted file system. 
     One of the preferred implementations of the invention is a client application, namely, a set of instructions (program code) or other functional descriptive material in a code module that may, for example, be resident in the random access memory of the computer. Until required by the computer, the set of instructions may be stored in another computer memory, for example, in a hard disk drive, or in a removable memory such as an optical disk (for eventual use in a CD ROM) or floppy disk (for eventual use in a floppy disk drive), or downloaded via the Internet or other computer network. Thus, the present invention may be implemented as a computer program product for use in a computer. In addition, although the various methods described are conveniently implemented in a general purpose computer selectively activated or reconfigured by software, one of ordinary skill in the art would also recognize that such methods may be carried out in hardware, in firmware, or in more specialized apparatus constructed to perform the required method steps. Functional descriptive material is information that imparts functionality to a machine. Functional descriptive material includes, but is not limited to, computer programs, instructions, rules, facts, definitions of computable functions, objects, and data structures. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, that changes and modifications may be made without departing from this invention and its broader aspects. Therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention. Furthermore, it is to be understood that the invention is solely defined by the appended claims. It will be understood by those with skill in the art that if a specific number of an introduced claim element is intended, such intent will be explicitly recited in the claim, and in the absence of such recitation no such limitation is present. For non-limiting example, as an aid to understanding, the following appended claims contain usage of the introductory phrases “at least one” and “one or more” to introduce claim elements. However, the use of such phrases should not be construed to imply that the introduction of a claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an”; the same holds true for the use in the claims of definite articles.