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 to fig2 , to automatically transfer a user profile to a web server 203 , the user profile information is first stored at a proxy server 202 in a database 220 . when a http data request 211 is received by the proxy server 202 from a web browser 201 , the user profile information from database 220 is encapsulated in a request 212 that is forwarded by the proxy server to web server 203 . the proxy server 202 encapsulates the user profile information in the request 212 by adding http headers containing the user profile information to the headers received in the request 211 . fig3 a and 3b shows fields in http requests . the fields 300 may be fields in a request 211 from a client computer 201 , and the fields 350 may be fields in a request 212 forwarded by proxy server 202 to a web site 203 . referring to fig3 a and 3b , each field 301 - 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 in field 302 indicates that request 300 originated at a “ mozilla / 3 . 0 compatible ” browser ; and the “ cookie :” field name in field 303 includes the value “ been_here_before ” is a web cookie . when a http request 211 having fields 300 is received at proxy 202 , the proxy server 202 can add user profile information to the request 211 by adding additional http fields 304 - 305 containing the profile information , thereby generating a new request 212 with the user profile information encapsulated in fields 304 - 305 . database 220 may be a local or remote database that can store multiple user profiles . for example , the database 220 may be a database storing user profiles on a hard disk directly connected to the proxy server 202 , or the database may be a sql database at a remote system and accessed over a tcp / ip connection . still other database 220 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 the database 220 based on the identifying information associated with a particular computer or user of that computer . to determine the user &# 39 ; s identity , a proxy server may use a table or database that associates user identity information with network connection information . for example , referring to fig2 , 4 a , and 4 b , when a client computer 201 connects to a network 230 , the client computer &# 39 ; 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 the proxy server 202 where it is stored in a database 220 ( step 400 ). when the proxy server 202 receives a subsequent http request 211 ( step 401 ), 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 the proxy server 202 has identified the user ( step 402 ), the proxy server can retrieve a user profile associated with that user from its database 220 . the proxy server may then add http fields containing user profile information to fields in the original http request 211 ( step 403 ). for example , header fields 304 - 305 may be added to the original header fields 301 - 303 from request 211 . field 304 may include unencrypted user profile data (“ username = john_doe , zipcode = 60609 , parentalcontrol = youngteen ), while field 305 may include encrypted user profile data . encryption of data in the field 305 may use the securedata protocol ( explained later ). the proxy server thereby forms the modified http request 212 containing the user profile data . the modified request 212 may then be forwarded by the proxy server for receipt at a web site ( steps 404 and 421 ). particular web servers may or may not be configured to recognize the user profile data fields 304 - 305 . a web server that is not configured to recognize the user profile fields 304 - 305 may ignore the fields . a web server that is configured to recognize the user profile fields 304 - 305 can extract the profile data from the field 304 - 305 ( steps 422 and 424 ). extraction of user profile data in the field 305 may include decryption of the user profile data in encrypted field 305 . the extracted user profile data can be used , for example , to generate or customize data sent in response 213 to the proxy server for forwarding as a response 214 to a user or client computer ( step 425 ). for example , a tourist information web server may customize a page based user profile data specifying a browser user &# 39 ; s age , and interest . if a web server looks for a user profile field 304 - 305 in the request 212 , 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 ( step 422 - 423 ). after the necessary data is obtained , the web server 203 can generate a response ( step 425 ). exchange of user profile data between a proxy server 202 and a web server 203 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 iis 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 a request 212 from the proxy server 203 is received at an iis or netscape server web site , the request 212 is passed to the proxy data exchange filter by the iis or netscape server software and the user profile data is extracted from the headers 304 - 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 request 212 ( e . g ., the original information from request 211 ), may then be processed by the web server to obtain response 213 information . a proxy server 202 and web server 203 may implement the securedata protocol so ( 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 ” in field 305 indicates that the field value segment of field 305 contains encrypted profile data . the securedata protocol uses multiple cryptography algorithms to provide secure user profile data transfers between a proxy server 202 and a web server 203 . 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 , in applied cryptography , 2nd edition , by bruce schneier , john wiley & amp ; sons , 1996 . user profile information may be encrypted at proxy server 202 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 . the proxy server 202 may encrypt user profile data and place it in a http field in request message 212 . the proxy server 202 can also separately encrypt the session key using a public key cryptography algorithm and the public key of the web server 203 . the public key encrypted session key may also be placed in the request message 212 , or may be sent separately to the web server 203 . when the web server 203 has received the encrypted session key and user profile data , the web server 203 can decrypt its session key by using the public key cryptography algorithm and the web server &# 39 ; s private key . the web server 203 may then decrypt the user profile information using the decrypted session key . fig5 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 to fig5 , when a request 511 is received at the proxy server 502 , 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 the request 511 , 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 , the proxy server 502 may then query its database to determine whether it has a valid public key for the web server 503 . if the proxy server 502 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 requests 514 to the web server 503 . if the proxy server 502 does not have a valid public key for web server 503 , the proxy server will obtain the public key from the web server 503 using a http request 512 . the request 512 includes a url that identifies a public key file (“ pub_key_file ”) stored on the server 503 . the public key file may include additional information used by the proxy server 502 . 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 ‘& lt ;’ and ‘& gt ;’ delineate fields in the public key file and brackets ‘[’ and ‘]’ delineate optional information ): the web server &# 39 ; s public key file is returned to the proxy server 503 in a http response 513 . the web server 503 may provide additional securedata protocol information in http fields of response 513 and / or in the public key file returned by the response message 513 . for example , http fields in response 513 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 . a proxy server 502 or web server 503 may check a securedata protocol version number returned in the public key file , in request 512 and / or in response 513 to ensure that the protocol is functioning properly and to recover from or to avoid errors . for example , if a proxy server 502 detects that protocol versions numbers in a retrieved public key file and those in a header of a response 513 do not match , the proxy server may re - submit the request 512 to the server 503 . when the request 512 is re - submitted , the proxy server 502 can include the http “ no - cache ” pragma to instruct caching systems between the proxy 502 and the web server 503 not to use cached data . this may help avoid errors introduced by using stale cached data . when the proxy server 502 has received the web server &# 39 ; s public key , it may cache the public key subject to a time - to - live ( ttl ) value specified by the web server 503 and / or the proxy server &# 39 ; s own ttl policies . if the proxy server 502 is unable to retrieve a web server &# 39 ; 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 request 514 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 &# 39 ; 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 the proxy server 502 . once the proxy server 502 has the public key of web server 503 , 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 or client computer 511 to form a modified request 514 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 request 514 . for example , referring to fig3 b , the field 305 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 &# 39 ; s or groups of web servers can have different session keys . a web server &# 39 ; 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 &# 39 ; s public key . other methods of generating unique keys can be used . the session key data can in field 305 ( 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 &# 39 ; 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 request 514 is received at a web server 503 , the web server may compare the ip address in the proxy ip field to help confirm that the request came from a particular proxy server 502 . if the addresses differ , the request 514 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 . the proxy server 502 can use a web server &# 39 ; s unique session key to encrypt user profile data that is add it to the field 305 . in some implementations , the user profile data may be placed in one or more additional fields . the request 514 , now containing the public - key encrypted session data and the symmetric encrypted user profile data , is then sent to web server 503 . when request 514 is received by the web server 503 , the request can be passed to proxy data exchange filter software that can extract the added fields 304 - 205 from the request 514 , decrypt the session key and the user profile information contained in the fields 304 - 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 request 514 back to the web server for further processing and for generation of a response 515 . the web server 503 can store received profile data in a local database for future request processing purposes . the web server 503 may return a shortcut token to the proxy server 502 . the proxy server 502 may add the shortcut token to a subsequent request 518 in place of the ‘ full ’ user profile data sent in the request 514 . this can be used to reduce the amount of data that needs be transferred in subsequent request 518 . a shortcut token can be an index value , database query information , file name , other pointer data , or an arbitrary value generated by the web site 503 and used to reference the stored user profile data . a web server &# 39 ; s public key file may be sent to the proxy server 502 using a security level specified by the site 503 . for example , a web site &# 39 ; 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 &# 39 ; 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 &# 39 ; s public key ( which may be the master key value ). shortcut token security levels may also be indicated using http fields in a response 513 or 515 , or may be specified using data stored in a configuration database at the proxy server 513 using a data entry terminal . a proxy server 502 or web server 503 may include other http fields in a request 512 , 514 , 518 or in a response 513 , 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 =& lt ; shortcut value | all & gt ;: the ‘ flush ’ directive can be sent to the proxy server 502 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 a web server 503 or proxy server 502 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 =& lt ; n & gt ;: 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 ( yip ) or network news transfer protocol ( nntp ). accordingly , other embodiments are within the scope of the following claims .