The present invention relates generally to encryption and transmitting methods and, more particularly, to methods and systems for encrypting and transmitting electronic information and files.
Computer users may request access to files or other electronic information from remote computer devices. For example, a user on a laptop computer connected to the Internet via a wireless connection may request a file located on a server that is also connected to the Internet. Providing a file or electronic information to a remote device introduces several security concerns. First, the files or electronic information may be intercepted during transmission. Even if the files and electronic information are encrypted, there are risks that an interceptor will be able to decrypt the encrypted files or information. Second, after transmission, the requested file or electronic information may be stored on the user's remote client device. If the remote client device is lost, stolen, or operated by a user who should not have access to the file or electronic information, there are risks of unauthorized access. Conventional methods address these issues separately. For example, some conventional applications provide encryption for transmission and others provide encryption for storage.
Embodiments of the present invention comprise methods and systems for securely providing files or other electronic information to a user on a remote client device. One aspect involves an access server receiving a request for a file from a client device that identifies a user and the client device, encrypting the file using a session key based at least in part on the user and the client device, and transmitting the encrypted file to the client device. Other aspects of the invention include storing the encrypted file on the client device in the same encrypted form such that the file may only be decrypted or accessed by the particular user on that particular client device.
Another aspect of the present invention includes a system having a server and a client device. The server is capable of receiving a request for a file from a user on the client device. The server is also capable of encrypting the requested file based at least in part on the user, the client device, and a session, and transmitting the file to the client device. The client device is capable of sending a request for the file to the server, receiving and decrypting the encrypted file from the server, and storing the file.
These illustrative embodiments are mentioned not to limit or define the invention, but to provide examples to aid understanding thereof. Additional illustrative embodiments are discussed in the Detailed Description, and further description of the invention is provided there. Advantages offered by the various embodiments of the present invention may be further understood by examining this specification.
These and other features, aspects, and advantages of the present invention are better understood when the following Detailed Description is read with reference to the accompanying drawings, wherein:
a-b show an illustrative file request and response according to one embodiment of the present invention;
Embodiments of the present invention comprise methods and systems for securely providing files or other electronic information to a user on a remote client device. There are multiple embodiments of the present invention. By way of introduction and example, one illustrative embodiment of the present invention provides a method for securely providing a file to a remote client device by various encryption techniques involving an access server key, a user/device key and a session key. In this example, the client device sends a file request to an access server. The file request is encrypted based on an access server key. The client device also sends a user/device key along with this encrypted file request. This user/device key itself is based on both a key associated with the particular user and a key associated with the particular device.
The file request that is received at the access server is decrypted using the access server key. The access server retrieves the file from storage, for example storage on a data server, and generates a session key. The session key is unique for the client, device, and session. The retrieved file is encrypted using the session key. The encrypted file and the session key are then together encrypted using the user/device key into a message that is sent to the client device.
The client device receives and decrypts the encrypted message using the client/device key. This yields the session key and the requested file, which is still session-key-encrypted. The session-key-encrypted file is stored locally on the hard drive of the client device. The session key is also stored locally. Access to the session key is restricted such that only the particular user on the particular machine can access the session key. Accordingly, only the particular user on that particular machine can decrypt the locally stored session-key-encrypted file. While the session-key-encrypted file may be decrypted for display and edit on the client device, it is never stored on the client device in an unencrypted form. Accordingly, in many embodiments, the requested file is not transmitted or stored in unencrypted form, reducing the data exposure risks that would otherwise be present.
This introduction is given to introduce the reader to the general subject matter of the application. By no means is the invention limited to such subject matter. Additional illustrative embodiments are described below.
Various systems in accordance with the present invention may be constructed.
In general, a client device 120a-n may use any suitable type of processor-based platform, and typically will include a processor 121 coupled to a computer-readable medium, such as memory 122, and include hardware and user interface components (not shown). The computer readable medium 122 can contain program code that can be executed by the processor. It can be used to store information and applications such as a file request engine 123, an encrypt/decrypt engine 124, an access server public key 125, a device private key 126, and various other encryption keys and files, among other things.
The client devices 120a-n themselves may have differing characteristics. The client devices 120a-n may include cell phone devices, mobile phone devices, smart phone devices, pagers, notebook computers, personal computers, digital assistants, personal digital assistants, digital tablets, laptop computers, Internet appliances, blackberry devices, Bluetooth devices, standard telephone devices, fax machines, other suitable computing devices, or any other suitable electronic device. Additional components in the client devices may differ and provide various functionalities.
The client devices 120a-120n may be connected to a network 130 in a variety of ways. The network 130 is not limited to any particular type of network nor is it limited to a single network. For example, the network 130 may be the Internet, a LAN, a WAN, a private network, a virtual network, or any combination of suitable network types.
The access server device 140 can comprise a server executing file access, file retrieval, encryption, decryption, and transmission functions. Data store 160 can comprise a server that stores a file or other electronic content, possibly in a database 162. The access server device 140 comprises a processor 141 and memory 142 containing a file access engine 143, a file retrieval engine 144, an encryption/decryption engine 145, and an access server private key 146. Examples of devices 140, 150 are servers, mainframe computers, networked computers, processor-based devices, and similar types of systems and devices.
Systems having different architecture than that which is shown in
Referring now to
In some embodiments, both the client devices 120a-n and the users 110a-n will have private keys. The individual users may be given private keys in a variety of ways depending on the operating, client-server, and other network environment factors. For example, in some cases each user 110a-n is created on a domain. During creation on the domain, a private key is established for each user 110a-n. When the user logs onto or otherwise begins operating a given client device through their domain, the client device is provided with the user's private key.
The client device keys may be created at the time of deployment of each client device 120a-n. For example, when the client software is installed or initialized, each device 120a-n may receive a private key that is stored locally on the client device 120a-n.
Likewise, when the access server software is installed or initialized, the access server 140 may also be given a private key. The access server public key may be distributed to the client devices 120a-n in a variety of ways. For example, upon installation or initialization of client software on the client devices 120a-n, the access server public key 125 may be distributed to and stored in the memory 122 of the client device 120a, as shown in
Many of the embodiments discussed herein describe the use of asymmetric encryption techniques and algorithms, such as pretty good privacy or PGP algorithms. These techniques are used only for purposes of example and are not intended to limit the invention. Modifications of the present invention that use alternative encryption techniques will be understood through examination of the embodiments herein. Moreover, use of the term “key” is not meant to limit the scope of the invention. A key is a series of elements (typically alphanumeric letters and/or numbers) that enables use of an encryption algorithm to encrypt and decrypt data. Other identifying information may substitute for an encryption key in certain embodiments.
Referring now to
In block 404, the encrypted file request 310 is sent from the client device 120a to the access server 140. The electronic transmission may include travel over the Internet, WANs, LANs, and/or any other suitable network or combination of networks.
Referring now to
The user/device public key 312, which is included as part of the file request 310 and an associated user/device private key may be derived in a variety of ways. For example, the user/device public key 312 could be derived from the associated user/device private key, which may be derived from the xor'ed user private key and client device private key. In some embodiments, the entire file request 314 will be encrypted, in other embodiments, some or all of the file request may not be encrypted. For example, public user/device key 312 will not be encrypted in some embodiments.
Referring now to
Once the file request 310 is decrypted, the access server will typically determine if access to the file is allowed as shown in block 506. This determination may be based on a determination of whether the request is valid and appropriate given the user 110a and client device 120a. For example, the access server 140 may determine whether the file actually exists, whether the user 110a has permission to access to the requested file, whether the client device 120a has permission to access the file, and whether the file is available, among other things.
Referring now to
Data store 160 may be located on a private network 150, or, alternatively, on a public network such as the Internet. In the case of a private network 150, in most cases the access server's file request 320 and the data store's response 330 will not need to be encrypted. In the case of a public network, the request 320 and response 330 will generally be encrypted to protect the request and file against unauthorized capture. Such encryption may be by convention encryption techniques or utilize the techniques taught herein, i.e., by encryption using a session key 342 generated by the access server 140.
Referring again to
Referring now back to
Referring now to
The access server 140 may generate a session key 342 in a variety of ways. For example, the session key may be created based on the identity of the client device 120a, the user 110a, and/or the particular connection session. Alternately, the session key can be a pseudo-randomly generated number, seeded perhaps with a timestamp. The primary characteristic of a session key, regardless of its generation, is that it cannot be derived from any other key in the system and that it can be realistically considered unique. The session key 342 may be timed to expire after a given time and/or may be automatically destroyed or erased when the user 110a logs off of or otherwise terminates use of the client device 120a.
Referring now to
Assuming that the decryption is successful, the client device 120a will next retrieve the session key 342 and use it to decrypt the encrypted payload 314 containing the requested file or related message. If the response 340 or any of its subparts such as the session key 342 or payload 314 are compressed, the client device 102a may also uncompress the content as required.
If the response 340 indicates that the requested file was unavailable or that some error condition occurred, the user 110a may be notified immediately, for example, in a dialog or popup window.
If the response 340 indicates that the file is contained therein, the file may be re-encrypted, generally by itself, with the provided session key 342 and stored in the memory 122 of the client device 120a, as shown in block 410. In some embodiments, the session key 342 is stored in a secure location in memory 122 along with a reference to the file. In some embodiments, the session-key-encrypted requested file will be stored on the client device 120a prior to decryption.
Once the encrypted file is stored in the client device memory 122, the file may be launched by initiating or executing any necessary operating system and/or application function. Thus, in many embodiments, while the requested file may be displayed in decrypted form through the applications and operating system on the client device 120a, the requested file is always stored in encrypted form.
If the user makes any alterations to the file, the alterations are saved by creating a new file that is also encrypted with the session key 342. The changed file may also be saved to the remote data store 160 in a variety of ways according to the present invention. In some embodiments, the user 110a will initiate the remote save function through the application or operating system. For example, a user 110a may select a “File->Save As” function. The client software residing in memory 122 will generally confirm that the user 110a has the appropriate privileges to write changes to the file. The client device 120a may then initiate a compressed, encrypted request to the server with the change to the file or a changed version of the file. The payload of this request will typically be encrypted with the session key 342 for that file, while the request will typically be encrypted with the server's public key, and, in addition to the changed file, may include identifiers of the user 110a and client device 120a.
Upon receiving this request from the client device 120a, the access server 140 will decrypt the request with the server private key. If the server cannot decrypt the request, then it may log the event, dump the request, and/or send a response. After successful decryption of the request, the access server 140 may use the session key to decrypt the file, the access server 140 may validate the user 110a and client device 120a credentials supplied, then, based on the user's 110a privileges, either overwrite the file stored on the data store 160 and generate a success response or generate an error response. The error response will generally include a unique identifier for the server. The error response will generally be compressed and encrypted with the user/device public key and sent back to the client device 120a.
Upon receipt of the message, the client device may attempt to decrypt it with the user/device private key. If no user/device private key exists, then the situation should be logged, and the message should be dropped with or without user notification. If decryption is successful, the message should be decompressed and displayed to the user 110a.
There are many advantages to implementing file request, retrieval, and storage systems and techniques according to the teachings of the present invention. For example, in many embodiments the file will only be accessible to the specific user on the specific machine. Thus, if the client device 120a is lost or stolen, the encrypted file will not be accessible to the finder or thief. Moreover, if the file is transferred to another device, it will not be accessible even by the same user. This prevents the unauthorized dissemination of sensitive data.
Another advantage in some embodiments is that a file intercepted during transmission may have multiple layers of encryption. In many embodiments, both the response message 340 and the file contained within the message's payload 344 may be separately encrypted. The multiple layers of encryption make it more difficult for an interceptor or hacker to get to the underlying file. As another example, the present invention may be used in combination with additional encryption techniques, such as conventional encryption techniques and/or techniques disclosed in the application entitled “Systems and Methods for Mutual Authentication of Network Nodes,” filed concurrently with this application Ser. No. 11/154,800, and incorporated herein in its entirety by this reference. Additional layers of encryption provide additional security.
Another advantage is created in some embodiments in which the session key is created with a set expiration time. Once time expires, the user 110a will not be able to access the file. This further protects the file stored on the local device from unauthorized use and interception.
While the above description contains many specifics, these specifics should not be construed as limitations on the scope of the invention, but merely as exemplifications of the disclosed embodiments. Those skilled in the art will envision many other possible variations that are within the scope of the invention.
The present application claims priority to U.S. provisional application No. 60/583,765 entitled “Controlling Use of a Mobile Work Station Based on Network Environment,” filed on Jun. 28, 2004, U.S. provisional application No. 60/653,411 entitled “Creating an Environment for Secure Mobile Access Anywhere” filed on Feb. 16, 2005 to Sanda et al., and U.S. provisional application No. 60/652,121 entitled “Remote Access Services” filed on Feb. 11, 2005 to Sanda et al.
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