US20130179677A1 - Secure data exchange between data processing systems - Google Patents

Abstract

A data transfer method performed at a proxy server includes intercepting a data request from a client computer that is directed to a target server, encrypting profile information, augmenting the data request by adding the encrypted profile information to the data request, and sending the augmented data request to the target server. A data transfer method that is performed at an information server includes receiving a data request from a proxy server, extracting profile information added to the data request by the proxy server, using the extracted profile information to generate a response, and sending the response to the proxy server.

Description

BACKGROUND
• FIG. 1 shows acomputer network100 that includes both client computers111-113 and server computers131-133. Thenetwork100 also includes data connections that allow the client computers to communicate with the servers. Those data connections include access connections114-116, a service provider's point of presence (POP)110,network120,proxy server117, andnetwork130.POP110 includes data communications equipment that allows a client computer111-113 to connect to thenetwork120. For example,POP110 may include dial-up modem banks, cable modem banks, a T1 interface, wireless communications equipment, or other data transmission equipment.
• After a client computer111-113 has been connected to the network120 (through POP110) it may exchange data with other computers on thenetwork120. Computers ondifferent networks120 and130 also can exchange data with each other by sending their data request toproxy server117 which, in turn, can forward their request to the destination computer, obtain a response from the destination, and return the response to the requesting computer.
• The servers131-133 and clients111-113 may communicate with each other using the hypertext transfer protocol (HTTP). HTTP is a data communications protocol that is used by web browser programs (such as Microsoft Internet Explorer and Netscape Navigator) to communicate with web server applications (such as Microsoft Internet Information Server and Netscape Server). Thus, by executing a web browser, a client computer111-113 can exchange data with a server131-133 that is executing a web server application.
• When a web server receives a HTTP data request from a browser, a web server application, such as a Common Gateway Interface (CGI) script, may be used to query databases, customize responses, and/or perform other processing used to generate a response. The web server application may need data about the client computer, the browser, its user, and/or other data in order to complete its processing of the data request. For example, a web server application may provide customized weather information based on a user's home address. The web application may obtain the user's address information by sending a data input form to the browser and receiving a user's response that contains the needed information. A web server application also may obtain needed data from web server environmental variables that are populated by data in HTTP header fields, by a web server, and/or by a web server sub-component. For example, a CGI script's response to a data request may depend on the type of browser originating the request. The CGI script may access a HTTP environment variable (“HTTP_USER_AGENT”) populated by the web server using data from a “User-Agent” field in a HTTP header. The value of the HTTP_USER_AGENT variable identifies the type of browser originating a request so that the CGI script can customize its response to that browser.
• A web server and a browser also may exchange web cookies that contain data. A web cookie is data file that can be automatically exchanged between browsers and servers along with the request and responses exchanged between the browsers and servers. When a web cookie is received by a browser, it can be stored at the client computer. During future transactions with the web server, the web cookie (and any data that it contains) can be sent back to the web server. By using data stored in web cookies, a web server's need to request data from a user may be reduced. However, since web cookies are typically stored on a client computer, they may be deleted and their data lost. Furthermore, if a user moves to another computer, web cookie information stored on the user's original computer will be unavailable to that user. These factors may reduce the utility of web cookies.
• The present inventors recognize that information service systems, such as web servers, should provide convenient, secure, reliable, and simple means of interacting with users. The present inventors further recognize when a server must query a user for data or use web cookies for data storage and input, convenience, security, reliability, and simplicity may suffer. Consequently, the invention disclosed herein provides additional means of providing information to a web server application that may provide additional flexibility in implementing information systems.
SUMMARY
• In general, in one aspect, the invention features a data transfer method performed at a proxy server. The method includes intercepting a data request from a client computer that is directed to a target server, encrypting profile information, augmenting the data request by adding the encrypted profile information to the data request, and sending the augmented data request to the target server. In another aspect, the invention features a data transfer method performed at an information server. The method includes receiving a data request from a proxy server, extracting profile information added to the data request by the proxy server, using the extracted profile information to generate a response, and sending the response to the proxy server.
• In general, in another aspect, the invention features a computer program residing on a computer-readable medium. The program includes instructions for causing a computer to intercept a data request from a client computer that is directed to a target server, encrypt profile information, augment the data request by adding the encrypted profile information to the data request, and send the augmented data request to the target server. In another aspect, the invention features a computer program residing on a computer-readable medium that includes instructions for causing a computer to receive a data request comprising encrypted profile information that was added to the data request by a proxy server, extract the profile information added by the proxy server, use the extracted profile information to generate a response, and send the response to the proxy server.
• In general, in another aspect, the invention features a proxy server that includes a database, a network interface, a processor, and a memory. The database includes records storing user profile information. The network interface operatively couples the proxy server to a network to exchange data with a client computer and with a target server. The processor is operatively coupled to the network interface, the database, and a memory. The memory includes executable instructions for causing the processor to intercept a data request that is directed to a target server, retrieve a record from the database, encrypt profile information in the record, augment the data request by adding the encrypted profile information, and send the augmented data request to the target server
• In general, in another aspect, the invention features an information server that includes a network interface, a processor, and a memory. The network interface operatively couples the information server to a proxy server. The processor is operatively coupled to the network interface and to the memory. The memory includes executable instructions for causing the processor to receive a data request from the proxy server, decrypt user profile information added to the data request by the target server; and use the decrypted user profile information to generate a response to the data request.
• Implementations may include one or more of the following features. A reference token may be exchanged between servers and used to refer to previously exchanged profile information. The reference token may be placed in subsequent data request sent by the proxy server to the target in place of full profile information. The profile information that is encrypted by the proxy server can be stored in proxy server database records. The particular user profile information encrypted and included in a data request can be selected based on an identity of a client computer user or a browser user. The identity may be determined using the Internet Engineering Task Force IDENT protocol or by using another method.
• Implementations also may include one or more of the following features. Profile information may be encrypted at the proxy server using a session key as an encryption key, and may be decrypted at the target server using the same session key. The session key may be determined by the proxy server and sent to the target server using a public key cryptography algorithm and a public key associated with the target server.
• A data request may use the hypertext transfer protocol. Profile information extracted from the data request at the target/information server can be provided to a web application, such as a CGI script, that is used to generate a response.
• The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Implementations may provide advantages including reduction of redundant data entry, reduction of user data entry errors, secure storage of user data, and automated user profile determination and dissemination. Different encryption keys can be used for different information servers, and each information server may establish characteristics associated with its encryption key. A web site may dynamically generate, maintain, and change its unique encryption key. This may help to minimize risk of replay attacks, message forgery, and message tampering. In addition, implementations may support multiple levels of security.
• Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
• FIG. 1 is a computer network diagram.
• FIG. 2 is a computer network diagram.
• FIGS. 3A and 3B show exemplary HTTP headers.
• FIGS. 4A and 4B are flowcharts.
• FIG. 5 is a message flow diagram.
DETAILED DESCRIPTION
• Processing of an information request at a information server, such as a web server, can be facilitated by a data transfer mechanism in which data needed to process the request is stored at a proxy server and automatically transferred to the information servers. Such a data transfer mechanism can be used, for example, by an information service provider (ISP) or on-line service provider (OSP) to automatically transfer information about a user (a “user profile”) to affiliated web sites. Referring toFIG. 2, to automatically transfer a user profile to aweb server203, the user profile information is first stored at aproxy server202 in adatabase220. When aHTTP data request211 is received by theproxy server202 from aweb browser201, the user profile information fromdatabase220 is encapsulated in arequest212 that is forwarded by the proxy server toweb server203. Theproxy server202 encapsulates the user profile information in therequest212 by adding HTTP headers containing the user profile information to the headers received in therequest211.
• FIGS. 3A and 3B shows fields in HTTP requests. Thefields300 may be fields in arequest211 from aclient computer201, and thefields350 may be fields in arequest212 forwarded byproxy server202 to aweb site203. Referring toFIGS. 3A and 3B, each field301-303 includes a HTTP field name and a value associated with the field. HTTP field names identify the associated field value. For example, the “User-Agent:” field name infield302 indicates thatrequest300 originated at a “Mozilla/3.0 compatible” browser; and the “Cookie:” field name infield303 includes the value “been_here_before” is a web cookie. When aHTTP request211 havingfields300 is received atproxy202, theproxy server202 can add user profile information to therequest211 by adding additional HTTP fields304-305 containing the profile information, thereby generating anew request212 with the user profile information encapsulated in fields304-305.
• Database220 may be a local or remote database that can store multiple user profiles. For example, thedatabase220 may be a database storing user profiles on a hard disk directly connected to theproxy server202, or the database may be a SQL database at a remote system and accessed over a TCP/IP connection. Stillother database220 implementations may be used. Each user profile may be associated with a particular user or group of users. A user profile may be selected from thedatabase220 based on the identifying information associated with a particular computer or user of that computer. To determine the user's identity, a proxy server may use a table or database that associates user identity information with network connection information. For example, referring toFIGS. 2,4A, and4B, when aclient computer201 connects to anetwork230, the client computer's user may submit name and password information to a POP or to a login server. The POP or login server may then send the user name and network connection information unique to that user (such as a unique combination of TCP/IP address and port number) to theproxy server202 where it is stored in a database220 (step400). When theproxy server202 receives a subsequent HTTP request211 (step401), the proxy server can identify the user associated with the request by querying the database of stored name and network connection associations. A proxy server also may identify a user using the IDENT protocol. The IDENT protocol is an Internet protocol that allows a computer to ask another computer for the name of the user. The IDENT protocol is further described in Internet Engineering Task Force (IETF) document RFC1413.
• When theproxy server202 has identified the user (step402), the proxy server can retrieve a user profile associated with that user from itsdatabase220. The proxy server may then add HTTP fields containing user profile information to fields in the original HTTP request211 (step403). For example, header fields304-305 may be added to the original header fields301-303 fromrequest211.Field304 may include unencrypted user profile data (“UserName=John_Doe, ZipCode=60609, ParentalControl=YoungTeen), whilefield305 may include encrypted user profile data. Encryption of data in thefield305 may use the SecureData protocol (explained later). The proxy server thereby forms the modifiedHTTP request212 containing the user profile data. The modifiedrequest212 may then be forwarded by the proxy server for receipt at a web site (steps404 and421).
• Particular web servers may or may not be configured to recognize the user profile data fields304-305. A web server that is not configured to recognize the user profile fields304-305 may ignore the fields. A web server that is configured to recognize the user profile fields304-305 can extract the profile data from the field304-305 (steps422 and424). Extraction of user profile data in thefield305 may include decryption of the user profile data inencrypted field305. The extracted user profile data can be used, for example, to generate or customize data sent inresponse213 to the proxy server for forwarding as aresponse214 to a user or client computer (step425). For example, a tourist information web server may customize a page based user profile data specifying a browser user's age, and interest. If a web server looks for a user profile field304-305 in therequest212, and the user profile field is not present, the server may use “traditional” data input mechanisms (such as forms and web cookies) to obtain needed data from a user (step422-423). After the necessary data is obtained, theweb server203 can generate a response (step425).
• Exchange of user profile data between aproxy server202 and aweb server203 may implemented using custom filtering software (“proxy data exchange filter” software) that can be added to commercially available proxy and web site server software. For example, Microsoft Internet Information Server (IIS) provides an application programming interface known as the information server application programming interface (ISAPI) that allows custom filtering software to be added to an ITS web site. A Netscape web site server provides an application programming interface known as the Netscape server application programming interface (NSAPI) that may also be used to develop custom filtering software. When arequest212 from theproxy server203 is received at an IIS or Netscape server web site, therequest212 is passed to the proxy data exchange filter by the IIS or Netscape server software and the user profile data is extracted from the headers304-305. The extracted profile data may then be made available as HTTP environment variables, database entries, or other data exchange structures that can be used by web applications. The remaining header information in request212 (e.g., the original information from request211), may then be processed by the web server to obtainresponse213 information.
• Aproxy server202 andweb server203 may implement the SecureData protocol (described below) to encrypt user profile data. Encrypted user profile data may be indicated by a special HTTP header. For example, the field name “User-Profile-SecureData” infield305 indicates that the field value segment offield305 contains encrypted profile data.
• The SecureData protocol uses multiple cryptography algorithms to provide secure user profile data transfers between aproxy server202 and aweb server203. For example, the SecureData protocol may use the Rivest, Shamir, Adelman (RSA) public key encryption algorithm or the pretty-good-privacy (PGP) public key cryptography algorithm along with the RSA RC4 symmetric encryption algorithm. Additional information on the RC4 algorithm can be found, for example, inApplied Cryptography,2nd edition, By Bruce Schneier, John Wiley & Sons, 1996.
• User profile information may be encrypted atproxy server202 using a symmetric encryption algorithm. A symmetric encryption algorithm, such as the RSA RC4 algorithm, uses the same encryption key (referred to herein as a “session” key) to encrypt and decrypt data. Theproxy server202 may encrypt user profile data and place it in a HTTP field inrequest message212. Theproxy server202 can also separately encrypt the session key using a public key cryptography algorithm and the public key of theweb server203. The public key encrypted session key may also be placed in therequest message212, or may be sent separately to theweb server203. When theweb server203 has received the encrypted session key and user profile data, theweb server203 can decrypt its session key by using the public key cryptography algorithm and the web server's private key. Theweb server203 may then decrypt the user profile information using the decrypted session key.FIG. 5 shows further details of an implementation in which a request message may include both the encrypted session key and the encrypted user profile data.
• Referring toFIG. 5, when arequest511 is received at theproxy server502, the proxy server determines whether it should add encrypted user profile data to the request. To do so, the proxy server may extract a destination web site address from URL information in therequest511, and query a database to determine whether the destination web site is to receive user profile information and whether the information is to be encrypted. If the destination web site is to receive encrypted user profile information, theproxy server502 may then query its database to determine whether it has a valid public key for theweb server503. If theproxy server502 has a valid public key, the proxy server can use the public key to encrypt session key information that can be provided to a symmetric encryption algorithm to encrypt user profile data. The encrypted session key and user profile data may then be forwarded in requests514 to theweb server503.
• If theproxy server502 does not have a valid public key forweb server503, the proxy server will obtain the public key from theweb server503 using aHTTP request512. Therequest512 includes a URL that identifies a public key file (“pub_key_file”) stored on theserver503. The public key file may include additional information used by theproxy server502. For example, the public key file may include the length of the public key, a SecureData protocol version number, a list of supported encryption algorithms, and shortcut configuration information (“shortcut” information is further explained, below).
• An exemplary public key may have the format shown below (chevrons ‘<’ and ‘>’ delineate fields in the public key file and brackets ‘[’ and ‘]’ delineate optional information):
• • Exemplary Public Key File
  • <public key=length-of-key key>
  • [<Version=SecureData protocol version number>]
  • [<crypto=<encryption method>]
  • [<shortcut=[none|low|med|high|max]>]
• The web server's public key file is returned to theproxy server503 in aHTTP response513. Theweb server503 may provide additional SecureData protocol information in HTTP fields ofresponse513 and/or in the public key file returned by theresponse message513. For example, HTTP fields inresponse513 may specify a time to live (TTL) for the key. The TTL value can be used to indicate the period during which the public key is valid.
• Aproxy server502 orweb server503 may check a SecureData protocol version number returned in the public key file, inrequest512 and/or inresponse513 to ensure that the protocol is functioning properly and to recover from or to avoid errors. For example, if aproxy server502 detects that protocol versions numbers in a retrieved public key file and those in a header of aresponse513 do not match, the proxy server may re-submit therequest512 to theserver503. When therequest512 is re-submitted, theproxy server502 can include the HTTP “no-cache” pragma to instruct caching systems between the proxy502 and theweb server503 not to use cached data. This may help avoid errors introduced by using stale cached data. When theproxy server502 has received the web server's public key, it may cache the public key subject to a time-to-live (TTL) value specified by theweb server503 and/or the proxy server's own TTL policies.
• If theproxy server502 is unable to retrieve a web server's public key information or the public key information is otherwise unusable, the proxy server can add a problem report information to fields in a HTTP request514 to indicate why the public key information is unusable. For example, the proxy server may indicate that the key information has been corrupted or a protocol version number or encryption level specified in the public key file is not supported. If the a web server's public key information is unusable and, consequently, the SecureData encryption protocol cannot be used, a proxy server may continue to forward the HTTP requests from browser clients to the web server without adding additional SecureData proxy headers. Alternatively the proxy server may block or otherwise filter request to the web server. The specific behavior may be defined on a per-web server basis using configuration information stored at theproxy server502.
• Once theproxy server502 has the public key ofweb server503, the proxy server can use the public key to encrypt session key data. The encrypted session key data may then be added to HTTP fields in the request from a browser orclient computer511 to form a modified request514 that includes the public-key-encrypted session key information. The proxy server also can encrypt the user profile data using the session key information and a symmetric encryption algorithm and place the encrypted user profile data in HTTP fields in the modified request514. For example, referring toFIG. 3B, thefield305 includes session key data “session=a3f792b210dafad” that may be public-key encrypted, and user profile data “Profile=A389C2ZA845MRAS02VMA39v1Z93AYC39AC3ABCEG78BB” that may be encrypted using a symmetric algorithm.
• Different web server's or groups of web servers can have different session keys. A web server's session key may be formed by combining a “master” session key that is the same for a group of web servers with a key mask that can be used to create a unique session key for a web server or a group of web servers. For example, a 64-bit master session key may be combined with a 64-bit key mask using an exclusive-or (‘XOR’) operation, to yield a unique 64-bit session key. In some implementations, the master session key may be the proxy server's public key. Other methods of generating unique keys can be used. The session key data can in field305 (e.g., “session=a3f792b210dafad”) can include numerous sub-fields. For example, the session key data can include a master key, a key mask, a timestamp, a URL hash, a Proxy IP field, and an encoding scheme field. These fields can contain the following data:
• Master key: The master key is a value that is generated by the SecureData proxy server that can be combined with a key mask to generate a unique session key. The proxy server may periodically generate a new master session key. For example, a new master session key may be generated every n minutes. The Master key may be the proxy server's public key.
• Key mask: The key mask is a value generated by a SecureData proxy server that is unique to a particular web site and which can be combined with a master key to generate a unique session key for that web site. A master key and a key mask can be combined using an exclusive-or (‘XOR’) operation, by appending the keys together, or by another key combination algorithm. A new key mask may be periodically generated. For example, a new key mask may be generated every n minutes.
• Timestamp: A timestamp value may be added to the public-key encrypted data to make replay attacks more difficult. The timestamp value can be checked by the receiving web server and compared to the current time. If the difference between the timestamp value and current time exceeds a threshold value, the request may be denied or other error recovery or security procedures may be employed.
• URL hash: A hash value derived from a requested URL may be added to the public-key encrypted data to make forging or tampering more difficult.
• Proxy IP: The IP address of the proxy server be inserted in the session key data. When a request514 is received at aweb server503, the web server may compare the IP address in the proxy IP field to help confirm that the request came from aparticular proxy server502. If the addresses differ, the request514 may be rejected or other error recovery or security procedures may be employed.
• Encoding scheme: Encoding scheme data may be sent from the SecureData proxy server to a SecureData web server to identify how user profile data is encoded. For example, the encoding scheme value may indicate that profile data is in a binary (bin) form, or in name-value pair (nvp) form (which may be expressed using the Abstract Syntax Notation 1 (ASN.1) or other name-value coding scheme), or in another form.
• Theproxy server502 can use a web server's unique session key to encrypt user profile data that is add it to thefield305. In some implementations, the user profile data may be placed in one or more additional fields. The request514, now containing the public-key encrypted session data and the symmetric encrypted user profile data, is then sent toweb server503.
• When request514 is received by theweb server503, the request can be passed to to proxy data exchange filter software that can extract the added fields304-205 from the request514, decrypt the session key and the user profile information contained in the fields304-205, and make the user profile information available to web server applications. The user profile information may be made available to web server applications by setting HTTP environment variables, by storing it in a database, by placing it in shared memory, and/or using other data exchange techniques. The proxy data exchange filter software may then pass the request514 back to the web server for further processing and for generation of aresponse515.
• Theweb server503 can store received profile data in a local database for future request processing purposes. Theweb server503 may return a shortcut token to theproxy server502. Theproxy server502 may add the shortcut token to asubsequent request518 in place of the ‘full’ user profile data sent in the request514. This can be used to reduce the amount of data that needs be transferred insubsequent request518. A shortcut token can be an index value, database query information, file name, other pointer data, or an arbitrary value generated by theweb site503 and used to reference the stored user profile data.
• A web server's public key file may be sent to theproxy server502 using a security level specified by thesite503. For example, a web site's public key file include data indicating that the web site will use a specified one of the following shortcut key security levels:
• • none: If “none” is specified, the shortcut token is sent to the proxy server as a clear (e.g., unencrypted value).
  • low: If “low” is specified, the shortcut token is sent to the proxy server as a clear value and is accompanied by a hash of a previously requested URL.
  • medium: If “medium” is specified, the “low” security level information is further accompanied by a timestamp value.
  • high: If “high” is specified, the “medium” security information is further accompanied by the proxy server's IP address.
  • max: If “max” is specified, the “high” security information is further accompanied by a sequence counter value. The sequence counter value may be based on a initial URL hash, the key mask, or other value, and is incremented in subsequent transactions.
• At low, medium, high, and max security levels, the shortcut token and related security data can be sent in encrypted form using, for example, the proxy server's public key (which may be the master key value). Shortcut token security levels may also be indicated using HTTP fields in aresponse513 or515, or may be specified using data stored in a configuration database at theproxy server513 using a data entry terminal.
• Aproxy server502 orweb server503 may include other HTTP fields in arequest512,514,518 or in aresponse513,515,519 to control user profile data transfers and/or the operation of the SecureData protocol. For example, HTTP fields in requests and/or responses may specify the following directives:
• Flush=<shortcut value|ALL>: The ‘Flush’ directive can be sent to theproxy server502 to discard a specified shortcut token or to discard all shortcut tokens from a particular web server. The ‘Flush’ directive may also be sent to a web server to cause the web server to discard stored user profile data associated with a particular shortcut token or to discard all stored user profile data associated with the sending proxy server. This directive may be used by aweb server503 orproxy server502 that is performing a reset operation.
  • WrongKey: The WrongKey directive indicate that improper security protocol information was received. A proxy server that receives the WrongKey directive may re-send a request using a HTTP “no-cache” pragma. The “no-cache” pragma indicates that cached data should not be used to satisfy the request.
  • SendFull: A web server can issue a SendFull directive to indicate that a proxy server should send “full” user profile data (rather than a shortcut token) in a subsequent HTTP request.
  • TTL=<n>: The TTL (time to live) directive specifies a period (n, in seconds) during which a shortcut token is valid. Similar directives may be included in requests or response to indicate time-to-live values for other data, such as session keys and public keys.
• The invention may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Apparatus of the invention may be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a programmable processor; and method steps of the invention may be performed by a programmable processor executing a program of instructions to perform functions of the invention by operating on input data and generating output. The invention may advantageously be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each computer program may be implemented in a high-level procedural or object-oriented programming language, or in assembly or machine language if desired; and in any case, the language may be a compiled or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM disks. Any of the foregoing may be supplemented by, or incorporated in, specially-designed ASICs (application-specific integrated circuits).
• A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, server, proxy, and client protocols need not use the HTTP protocol. Alternate protocols and data formats may be used such as file transfer protocol (FTP) or network news transfer protocol (NNTP). Accordingly, other embodiments are within the scope of the following claims.

Claims (21)

1. A data transfer method performed at a proxy server, the method comprising:

intercepting a data request from a client computer that is directed to a target server;

encrypting profile information;

augmenting the data request by adding the encrypted profile information to the data request; and

sending the augmented data request to the target server.

2. The method ofclaim 1 further comprising:

receiving a reference token from the target server;

receiving a second data request from the client computer that is directed to the target server;

augmenting the second data request by adding the reference token to the second data request; and

sending the augmented second data request to the target server.

3. The method ofclaim 2 wherein the reference token comprises a reference to the profile information sent to the target server.

4. The method ofclaim 1 further comprising retrieving the profile information from a database based on an identity of a user.

5. The method ofclaim 4 further comprising using the Internet Engineering Task Force IDENT protocol to determine the identity of the user.

6. The method ofclaim 1 wherein encrypting profile information comprises determining a session key and using the session key as an encryption key.

7. The method ofclaim 6 further comprising encrypting the session key, and wherein augmenting the data request further comprises adding the encrypted session key to the data request.

8. The method ofclaim 7 wherein using the session key to encrypt the profile information comprises using the session key as a symmetric encryption algorithm encryption key, and wherein encrypting the session key comprises encrypting using a public key encryption algorithm and a public key associated with the target server.

9. The method ofclaim 8 further comprising obtaining the public key from the target server.

10. The method ofclaim 9 wherein obtaining the public key from the target server comprises sending a request to the target server to retrieve the public key.

11. The method ofclaim 1 wherein the data request comprises a hypertext transfer protocol (HTTP) request comprising a HTTP field, the target server comprises a HTTP server, and the client computer comprises a web browser application.

12. The method ofclaim 1 wherein the profile information comprises information associated with the client computer.

13. A data transfer method performed at an information server, the method comprising:

receiving a data request from a proxy server;

extracting profile information added to the data request by the proxy server;

using the extracted profile information to generate a response; and

sending the response to the proxy server.

14. The method ofclaim 13 wherein using the extracted profile information to generate a response comprises providing the extracted profile information to a web application and generating the response by processing the web application.

15. The method ofclaim 14 wherein providing the extracted profile information comprises setting HTTP environment variables at a web server and wherein the web application comprises a common gateway interface script.

16. The method ofclaim 13 further comprising storing the extracted profile information at the information server and associating a reference token with the stored profile information, and wherein the response further comprises the reference token.

17. The method ofclaim 16 further comprising:

receiving from the proxy server a second data request comprising the reference token;

extracting the reference token from the second data request;

accessing the stored profile information based on the reference token; and

using the stored profile information to generate a response to the second data request.

18. The method ofclaim 13 wherein extracting the profile information comprises decrypting the profile information.

19. The method ofclaim 18 wherein the data request further comprises a session key added to the data request by the proxy server and wherein decrypting the profile information comprises using the session key to decrypt the profile information.

20. The method ofclaim 19 further comprising decrypting the session key.

21-32. (canceled)

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