NO20011728L - Computer system and method for securely distributing information products - Google Patents

Description

The present invention relates to a method and a system for the secure distribution of information products, such as music, text, images and video, and for so-called peer-to-peer exchange of such products.

Information products, such as music, images, text and video, and also other information products such as software, can now be distributed electronically without creating a physical copy that carries the actual product. However, there are usually intellectual property rights such as copyright associated with the information product, and when such information is distributed digitally it is possible to produce an unlimited number of copies without any reduction in quality.

It is a well-known problem that unauthorized copies of software, so-called warez, are made available on the Internet. With the growing popularity of the MP3 (MPEG Audio Layer 3) file format, this problem has become significant also in the case of music, as a number of highly publicized cases have shown.

Several attempts have been made to reduce the importance of such problems. Software is often distributed in versions with reduced functionality or in versions that expire and stop working after a given period of time. A fully functional version will then be available by purchasing a key that unlocks the software. To avoid unauthorized copying of this full version of the software, information extracted from the hardware of the computer on which the software is installed may be encrypted and hidden in the software's code, so that the software can only be used on the computer on which it was first installed. This will be inconvenient for the user, especially when hardware is to be upgraded or the computer is to be replaced.

A number of efforts have been made with regard to copy protection of music and images, such as watermarks in the file to prevent copying. The Secure Digital Music Initiative (SDMI) has introduced a specification for a system to prevent the distribution of pirated copies of music.

Traditionally, it is the case that the intellectual property rights associated with a product are consumed at the first authorized stroke of the individual product. This means that the owner of the product (copy), even if he cannot make copies of the product, is free when it comes to reselling the product. When an information product is sold in the more abstract form of being downloaded from the Internet, it is very difficult to distinguish between the buyer's right to do as he likes with his product and the rights owner's right to restrict copying, since any movement of information between computers strictly taken involves the creation of new copies.

With the help of the present invention, it will be possible to make individualized copies of information products such as music, which largely prevents unauthorized copying while at the same time enabling the owner of the individualized copy to move it to another computer or device, or to change the copy by transferring its rights to the relevant copy to another. In particular, the invention describes a system that allows two users to exchange their rights to individual copies of respective information products, especially songs.

This is achieved by means of a trading system comprising a unique main server on a server computer, unique clients on client computers or devices, and one or more known publishing servers on server computers. The various units in the system communicate over a communication network, such as the Internet.

The main server comprises at least a user registration database with data related to all registered users, a database of information product lists with lists of authorized information products for each individual user, and an index file of authorized information products. According to one embodiment of the invention, the main server also includes the actual information products, while according to an alternative embodiment only the indexes are found on the main server, while the actual information products are found on publishing servers. The main server will also include a trade database with lists of information products that users want to exchange and which information products they want in exchange.

The publishing servers are servers from which the information products are uploaded. According to one embodiment of the invention, the information products are uploaded to be stored on the main server, while according to an alternative embodiment, the information products are stored on the publishing servers and downloaded directly to users who gain access to them via the main server. In order for information products to be indexed and stored on the main server, they must come from a known publishing server operated by an intermediary who is able to demonstrate that he has rights related to the information product he wishes to distribute.

The unique clients are user computers or devices that are able to access the main server. By using such a client, a user can be registered as a user of the system according to the invention by providing personal information in the user registration database. The registration procedure includes the generation of an encryption key that is unique to the user. This key is stored in the client as well as in the main server. After registration, he may purchase copies of information products that will be downloaded to his client computer or device as an individualized and encrypted copy of the information product. The information product is individualized in that it is encrypted using the user's key and in that information extracted from the hardware of the user client machine or device is incorporated into the header of the file. The file containing the information product remains encrypted on the user's client computer and can only be played or read using special client software that continuously decrypts the file during playback. When a user purchases an information product in this way, the file index of authorized information products on mainframe computers will be updated to include the relevant information product for that user. A similar list will be maintained on the client computer or device.

By using the client, the user will also be able to access the main server and register information products of which he owns a copy and which he wishes to exchange in the trading database together with a list of information products he is willing to accept in exchange. A user can only offer products that are in his list of authorized information products. If a user can find an information product he wants offered in exchange for an information product he already owns and wishes to exchange, he can initiate such a trade. The main server will then delete the respective information product files from the clients where they were originally stored, remove the respective information products from the lists of authorized information products for their original owners, and enter the information product in the list of the new owner. The main server also initiates a download of new individualized files with the respective information products to the new owner of the respective product. There is no need to transfer the original file from one client to another. If the user tries to keep a copy of the information product he gives away, by making a backup copy of the individualized file, he will not be able to access the contents of this file, since it has been removed from his list of authorized information products. If there is a difference between the list on the client and the list on the main server, the main server will overwrite the list on the client. This prevents the user from creating a backup copy of the list of authorized information products. As an additional security measure, the master server may deny access to a user with a list of authorized information products that does not match the list in the master server.

The client software according to the invention may comprise the player/reader for the information product itself, or it may be a so-called plug-in which enables the player/reader to read the file which is encrypted according to the invention.

The actual payment for an information product that is purchased in accordance with the invention is not part of the invention itself as such. A number of options for payment can be used, such as a subscription scheme, debiting an account, etc.

The various features of the invention appear from the attached claims.

The invention will now be described in detail in the form of a non-limiting example, and with reference to the attached drawings.

Figure 1 shows an overview of the system according to the invention,

Figure 2 shows an overview of the classes in a client according to the invention.

In the following example, an example of an embodiment of the invention related to the distribution of music is described. However, it must be understood that with only minor changes that will not lead away from the spirit and scope of the invention, the example can be modified to include the distribution of other information products, such as images, video or multimedia. The invention is not suitable for distribution of text files or other information that can be copied directly while it is being viewed, but it will be possible to distribute text for example as graphics or in other formats that allow display on screen, but not editing or copying.

Reference is now made to figure 1, which illustrates the system according to the invention. The figure illustrates a number of additional features which may, but need not, be present in a system constructed in accordance with the invention. The system comprises a number of unique clients 1 which preferably include an MP3 player, a playlist organizer, an audio equalizer, a web browser, replaceable skins (dynamic graphical user interface), peer-to-peer song exchange and auction capabilities, a window for targeted messaging, access to online CD trading and to an online database of MP3 songs, an integrated file search and ftp/http download client, and capabilities for unique file encryption, playlist tracking, and status notification about copyright. The client is preferably implemented as client software installed on a client computer or on another client device, such as a personal digital assistant (PDA).

The system further comprises a unique main database 2 which communicates with the clients 1 over the Internet 9 or another communication network. The main server includes features that enable peer-to-peer song exchange and auctions, online CD trading and online MP3 database. Tables or databases located on the main server include an unauthorized song list database 3 and an authorized song list database 4. There is one of each of these lists for each unique user. Furthermore, there is a database of registrations of unique users 5, a CD store and trade database 6, a database 7 with an index of authorized music files, and a database 8 with an index of unauthorized music files 8.

In addition, the system includes one or more known publishing servers 10 and it may also include one or more unknown publishing servers 11.

The system according to the invention allows two main variants. According to a first embodiment, the unique main server 1 does not contain the actual music files, only the databases 7, 8 of music file indexes. In this case, a user may search through the index databases 7, 8 to find songs he or she wishes to purchase, but the actual song will be downloaded from one of the publishing databases 10, 11. Alternatively, the owners of the publishing databases upload music files to the main server 2, and in that case, the music file index databases 7, 8 will be expanded to also include the actual music files. This second alternative can also be described as a system where one or more known servers 10 are operated by the operator of the main server 2, so that it or they are more or less integrated into the main server 2.

The following description is based on the option where files are stored in publishing servers 10, 11.

MP3 files may be stored on an unknown computer 11. The files will either be unauthorized and illegitimate (eg "Yesterday" by The Beatles, encoded or "ripped" from a CD published by Capitol Records), or they will be unauthorized and legitimate MP3 files stored on an unknown computer 11 but legitimately owned by the owner of the unknown computer (eg "Eat at Joe's" by "Joe's Bar and Grill Garage Band", not published by any record company).

Any of these unauthorized, illegitimate, or unauthorized, legitimate music files may be published by an unknown intermediary on an HTTP or FTP server 11 that is neither owned nor controlled by the operator of the main server 2. Authorized legitimate songs may be published on HTTP or FTP -server 10, which may be, but need not be, controlled by the operator of the main server, but by using known-server software, the authorized legitimate disseminator of songs can present a legitimate declaration of copyright ownership. The software for the known server 10 is available to intermediaries who wish to use the system according to the invention to publish authorized legitimate files from an independent server, or from a server owned by the operator of the main server. Intermediaries who use the software for known servers will be registered in the main database as known intermediaries.

On the main server 2 there will be a file index of MP3 files from known mediators (authorized legitimate) and a file index of MP3 files from unknown mediators (which may be unauthorized illegitimate or unauthorized legitimate), for the entire Internet domain (approximately 500,000 titles). These indexes are stored respectively in the database of authorized music file indexes 7 and the database of unauthorized music file indexes 8. These databases 7, 8 are open and can be searched by all client computers 1 equipped with client software. The index of authorized music files is periodically expanded by intermediaries using the software for known servers, and the index of unknown music files is expanded by searching the Internet using search programs on the main server 2. Cleanups in the index are done for dead links and unreliable servers.

Using the client software on his client computer 1, a user can search online using keywords by artist, song title, publisher or genre, and he will receive "hits from the index. The user can then select files he wants to download from the list of hit and initiate downloads by clicking the download button.

After the request from the user, the client 1 will be connected to the known 10 or unknown 11 HTTP or FTP server and the download of MP3 files to the user will be initiated. Downloading can be direct from another client 1 (peer-to-peer), but such a music file will only be playable if it is an authorized legitimate file. An important feature of the invention is that the unique player will only play uniquely encrypted files, that is, only known servers are capable of encrypting files, and unauthorized illegitimate files received via peer-to-peer transfers will not be playable on the G-MP3 client.

If the file is from a known server 10, it is an authorized legitimate file, and the words "authorized copy" will appear with the download message, and also with the file when the song names appear in the unique song list. Furthermore, the file will be encrypted with an encryption key that is unique to the user when the file is downloaded from the known server. This unique file can only be played using the player that is part of the client to which it was downloaded. If the user transfers the player and the file to another machine, the song will not be able to be played until the user re-confirms with their anonymous username and password. This is achieved by including unique hardware information extracted from the user computer 1 in the encrypted file. After a re-verification, the player and file will not work on the client that the software was on before the transfer (re-verification).

Because of this, the system according to the invention makes it extremely difficult for the user to distribute additional copies of the file, via peer-to-peer file sharing, either

these files are transferred separately or together with a copy of the player. However, if the user wishes to exchange authorized, legitimate files via peer-to-peer, this will be made possible and controlled using a corresponding method with a unique player and unique file encryption.

If the MP3 file is from an unknown server, it is either an unauthorized, illegitimate file or an unauthorized, legitimate file. Then the words "unauthorized copy" and a "copyright warning" will appear along with the download message, and the MP3 file will also be tagged with the same message when the song title appears in the unique playlist. Furthermore, the file will be encrypted with the user's unique encryption key when downloading to the known client 1 (each copy of the kl i ent program item will be numbered and therefore "known", but the user remains anonymous). Again, this unique file will only be playable on the client computer 1 to which it was downloaded, meaning that the user will not be able to redistribute the unauthorized copy. If the user transfers the player and the file to another machine, the song will no longer be playable until the user re-confirms with their anonymous username and password. If the user transfers the file to another machine, the song will not be playable without the authorized player it was downloaded to.

In any case, the encryption software only allows the MP3 file to be played on the unique copy of the client software on the unique client computer 1, and it would be extremely difficult to play the file on another computer. The other user would have to obtain a second unique copy of the client software and go back to the source server to obtain a second copy of the file, and this file would also be encrypted and unique, either by the known server or by the known the client.

The unique master server 2 anonymously tracks, in a database 3, 4, the list of songs downloaded to each unique player 1. The players are tracked by number and the users remain anonymous. The user can freely trade or sell authorized songs from his song list to other users. Unauthorized songs can be removed at any time by removing them from the main database. A song will not be playable after this because to decrypt the song for playback, the song list on the client is scanned for verification, and this list is periodically updated from the main list when the client is on-line.

According to a preferred embodiment of the invention, legitimate paid advertising messages are sent to the user while the user is on-line and these are used by the client software.

Users of client computers 1 are able to purchase music through online CD purchasing, peer-to-peer exchange, or auctioning of legitimate music files or CDs, or to trade legitimate music files or CDs.

When users first log into the main server 2 using their client computers, they will be able to download client software which, when installed on the client computer or device 1, enables it to operate in accordance with the invention . The user must register either before downloading the software, or the first time he logs in using the client software, and he will then be registered in the user registration database 5. The client software will be uniquely numbered, and a unique encryption/decryption key will be generated and stored on user's computer 1.

A more detailed description of the client software will now be given. The player consists of a core and a user interface. The application form contains the machine used for processing MP3 files. A number of such machines are available, such as the Freeamp player. The Freeamp player would be preferred for this implementation because it is open source, free, and uses fewer resources than if another Java technology (JMF or the SPI facilities from JDK2.1.3) had been used. The Freeamp engine was developed using the standardized language C, so it should be portable to any platform after recompilation. In order for the Freeamp core and the rest of the application to be able to communicate, JNI (Java Native Interface) is used. This is used to define the internal methods ("native methods") that are implemented in the Freeamp core, and which are accessed from the rest of the modules. It contains methods used to process MP3 files (e.g. Play), methods for processing control (e.g. pause and stop), methods that return information about the file being processed (e.g. length in seconds, number of frames, artist's name) and methods to control the volume and frequency of the sound card of the client computer 1.

The player and the virtual store have an architecture that is based on the doc/view architecture. This means that the functionality of the new module is described in doc and the interface in view. With this technology, it is much easier to change interfaces.

The application architecture of the player is illustrated in Figure 2.

The player's FTP download classes (no.anet.download.ftp) include classes to handle FTP transfers, signaling that an FTP exception has occurred, etc. Similarly, the HTTP download classes (no.anet.download.http) include classes to handle downloading of individual files, declaration of constants used during HTTP file transfer, signaling that an HTTP exception has occurred, tracking download status, etc.

The core classes for the player (no.anet.MP3.Core) include classes that handle encoding a bytes/string array to base64 encoding, creating the user's default directories ("default directories"), searching for songs in the local MP3 the database, initializing the MP3 player with a "Play" call, opening files to be played, verifying that the file is authorized (ie, it is authorized for playback on this player and on this computer), sending the user's key to the server, handling MP3 exceptions, etc. The core classes also include classes to create threads that download selected files from a specified URL, handle data used to serve ads, etc.

The player's encryption classes (no.anet.MP3.Crypto) handle encryption and decryption. A file stored locally is downloaded "part by part". Each part of the complete file is encrypted, and then the encryption thread stores it in the local file. When the song is played, each bit sent to the player to be played will be decrypted first. Three types of encryption/decryption algorithms are supported: RC4, DES and DESede. A class is used to generate the user's encryption key. There are three algorithms supported by this class that can be used for generation: RC4, DES and DESede. A very important class for the encryption/decryption process contains two methods. The first (which is also the constructor), initializes the encryption/decryption mechanism with a specific key (read from a file) and sets the encryption/decryption algorithm. The other performs the actual encryption/decryption.

The player also includes classes to handle dialogs, skins, playlists, XML, list of authorized songs, searching remote databases, as well as classes to handle commerce, such as offering or ordering songs.

The client application is a skin-based application that allows the user to import Winamp skins and use them. The application is an XML-based application. The application properties and skin properties are both stored in XML files. In this way, it is much easier to modify application properties and skin properties without rebuilding the entire application.

The client application is made of four main modules: player, playlist, graphic equalizer and search.

The player module acts as a kind of secretary for the entire system. Essentially, it receives commands from the user and ensures that these tasks are performed by making method calls to objects. A Freeamp core is used to access MP3 files. It is described in further detail below.

The player module is 70% Winamp compatible, which allows the user to import Winamp skins and to complement these with own images, images that Winamp skins do not contain (eg images used for buttons that activate trading functionality or search windows).

The user can modify the appearance of the player by using the tool to change the layout. With this tool, the user can create a new layout for a specified skin, and in addition, the user can change skin colors with the tool to change skin colors. Both results, for layout and colors, are stored in the relevant skin's XML.

The playlist manager contains the active playlist. A playlist is a list containing MP3 files; it contains authorized and unauthorized MP3 files. The authorized and unauthorized songs are shown with different colors. The user has the ability to create a playlist, to add new songs to the playlist, to remove songs from this list, to save, load and delete the active playlist. This module is 70% Winamp skin compatible. To add a song or file directory to the playlist, the user simply clicks on the "open" button, and with the "open file" dialog, he selects the relevant song or file directory, to which the file is automatically added.

Sometimes an MP3 file, just like any other audio recording, can sound better if different parts of the frequency spectrum of the file are adjusted. The client software includes a graphical equalizer to help users fine-tune playback to their preference.

The equalizer allows users to save equalizer settings in a preset file. These files contain the equalizer values in XML files. Additionally, the user can associate preset values to a specified MP3 file. As soon as automatic loading of presets is activated, the equalizer values are automatically loaded when the specified MP3 file is processed.

There is a search engine client integrated into the software. With this search engine, users can search for MP3 songs on the Internet or in the users' list of authorized songs. To search the Internet, the client computer 1 is connected to a server, and after sending a request to the server and receiving the search results, the client displays the results in the results list. Using the returned list of MP3 files, the user can select files for download or preview. When authorized songs are downloaded, they are automatically encrypted using the user's unique key. This way, the file cannot be played by another player, only with the user's unique client on the user's client computer 1. To search the list of authorized songs, a request is sent to the AuthorizedSongList for the specified song.

FreeAmp is the player core module used to process the MP3 files. FreeAmp is the result of an open source project to build the best digital audio player available.

FreeAmp is a modular media player designed to be easily expandable to new media types, sources and targets. FreeAmp achieves this by abstracting the important parts of the functionality into a plugin architecture.

Reference is again made to figure 1. The main server 2 includes or manages a number of databases. The database 3 with lists of unauthorized songs contains a list of songs users have downloaded to their client computers 1 from unknown publishing servers 11 using the system according to the invention. As previously described, these songs will be encrypted using the users' unique keys, and thus they will be unique so that they cannot be played on other client computers unless they are changed or updated using the system according to the invention. This database contains a list of unauthorized songs for each user. When an unauthorized song is transferred from one user to another as a result of a trade, the song is deleted from the first user's list and added to the second user's list.

The authorized song list database 4 is similar to the unauthorized song list database 3 in that it contains a unique list of songs for each user. However, these lists contain songs that the user has obtained either by purchasing the song from a known publishing server 10 or by receiving an authorized song from another user as part of a trade. Of course, the system can be designed to handle only the trade and barter of authorized songs. In this case, the database 3 with lists of unauthorized songs will not exist, only the database of authorized songs. The individual user lists in these databases will be duplicated on each user's client computer 1, and the client will not play encrypted songs that are not present in one of these song lists, even if they can be decrypted using the user's key. The lists on the respective user's client computer 1 will be updated each time a user makes a purchase or trade, and e.g. every time the user is online. As an additional security measure, it is possible to deny access to a user who has tampered with his playlists by replacing one of them with an older backup version containing songs he has already transferred to another user.

The client will of course be able to play any unencrypted song, as these may be legally recorded by the user.

The user registration database 5 contains a list of all registered users. Nål-en user is first registered, relevant information is entered into this database. It is possible to implement the system as an anonymous system where users are only registered with their username and the serial number of the client software, or they can be registered with their name and address. The first may be preferable to maintain privacy e.g. if the users receive targeted advertising based on their behavior, while the latter may be preferable if the main server is also to handle e-commerce such as receiving orders and credit card payments for songs purchased from known publishing servers 10, CDs or other goods. Of course, it is also possible to create a system where personal information and information about behavior cannot be combined, but the design of such a system is outside the scope of this invention.

Any user registered in the user registration database 5 will have one and only one corresponding song list in each of the song list databases 3, 4, and each song list in the song list databases 3, 4 will be associated with one and only one user in the user registration database 5.

CD'trade and barter database 6 contains an overview of "items" available for sale or exchange. These may be CDs or other goods, in which case they may be handled by e-commerce or auction systems that are outside the scope of this invention, or they may be songs offered by users or by known intermediaries or requested by users. Songs offered are listed accordingly. If they are offered for exchange by a user, other users will be able to send responses to the user with lists of songs they are willing to exchange for the offered song. Songs that are in demand are listed as in demand, along with songs that can be offered in exchange for the requested song. Songs offered in exchange in this way may be offered as alternatives, in combination (collectively) or as alternative groups of one or more songs.

The songs offered or requested in the trade database 6 can be found by searching or browsing. According to a preferred embodiment of the invention, the songs are arranged by artist, record company, music category, year of publication and/or other categories that make it easier for users to find. This information can be encoded into the files when they are first offered by known intermediaries/distributors, and songs will thus be categorized automatically.

The authorized music file index database 7 contains an index of all songs available from known publishing servers 10. These songs are recorded in the index database 7 when a promoter uses the known promoter software to upload a song to a known publishing server 10 (which may, but not needs to be operated by the operator of the main server 2), and registers the song in the main database 2. This index is available for searching by the client computers 1.

The Unauthorized Music File Index Database 8 contains an index of songs available from unknown publishing servers 11. It is not possible for the main database to verify whether these files are legitimate or infringing copyright. In this sense, the database of unauthorized music file indexes 8 is equivalent to search engines on the Internet. It is simply an index of files that are available. However, a file found using this index and downloaded using the client software on a client computer 1 will be encrypted using the user's unique key, and the user will not be able to distribute further copies of the file.

In the following description, it is assumed that all computers involved are online. In the event that one or more computers are off-line, messages will be stored and forwarded by the main server, they can be sent as e-mail, or certain actions will have to be postponed until the relevant computer is online again. Professionals in the field will realize that this can be handled in a number of different ways which in this context are rather trivial.

If, using his client computer or device 1, a user finds songs that are offered and that he wants, or songs that are in demand and that he is willing to give in exchange for the songs that are offered in exchange for the desired song, he can respond to the offer or request. If he responds to an offer, a message will be sent from the responding user's client computer to the client computer of the user behind the offer. This message indicates which song or songs the user is willing to give in exchange for the offered song. The user behind the original offer can then review received messages and accept or reject them.

If a user using his client computer finds songs that are requested and that he has, and the song(s) offered in exchange for the desired song are songs he wants, he can indicate which song or songs of those offered in exchange for the song he can offer and accept the barter.

When a barter is accepted in one of these ways, a number of steps are performed. Each user receives a file of the song offered by the other user. This file can be transferred from the original user to the new user, but in that case it must first be decrypted using the original user's key before being encrypted using the new user's key. Preferably, the file is downloaded from a publishing server 10, 11 which is found using one of the index file databases 7, 8 in the main server 2. Each file is encrypted using the key of the receiving user. The encryption can be performed either by the known publishing server 10 using a copy of the key received from the main server 2 or the user client computer 1, it can be performed by the main server 2 using the user's key stored in the user registration database 5, or it can be encrypted by the user client computer 1 using client software and the locally stored user key. Each of these options has advantages and disadvantages. The first option means that the user's key must be transferred over the Internet every time a file is encrypted. The second option means that every download must be routed through the main server 2. The third option means that the file will not be encrypted until it is received by the client computer 1, and that a sniffer at the input port of

the computer may be able to make an unencrypted copy of the file. It is a matter of implementation choice to choose the alternative that appears as

preferred. Files are encrypted and downloaded part by part, and they are also handled this way during playback, when each part is decrypted and fed into a buffer.

Of course, the option of sending the key to the publishing servers cannot be used when the publishing server is an unknown publishing server 11, since such a server will not be equipped with known server software enabling it to handle the encryption.

When the header of the file is encrypted, information unique to client computer 1 will be included. This information can e.g. be the serial number of the hard drive or network card. The unique serial number of the client software is also included. This way, the file can only be played by the unique client software used to download it, on the unique hardware it was downloaded to, and only with continued access to the user's key. If the client software is replaced, moved to another computer, or if the hardware is upgraded, the user will have to register again, and all the header files of his car's songs will be updated accordingly.

When a song is downloaded to a client computer 1, it is entered into the list of authorized or unauthorized songs on the client computer 1, and also into the user's song list in either the authorized 4 or unauthorized 3 song list database on the main server 2. If the song was downloaded as a result of an exchange, as described above, the song(s) given in exchange for the new song will be deleted from the relevant song list. There is no need to delete the actual encrypted song from the client computer, since the song can no longer be played after it is removed from the user's list of songs.

In a preferred embodiment, all exchange of song files, keys and other user information including serial numbers is done using secure communication, such as SSL and HTTPS (HTTP over SSL).

Encryption of song files and song lists is preferably done using RC4, DES or DESede. The key length for user keys used for encryption is preferably 64 bits. This bit length allows sufficiently strong encryption while not requiring too much processing power for a relatively simple client computer to decrypt a file during playback. Other bit lengths may be chosen based on other implementation specifications.

Claims (60)

1. Computer system for handling secure distribution of information products, where said information products are distributed in digital form and encrypted with an encryption key that is unique to a receiving user, characterized in that it comprises a database (4) with registrations of authorized downloads of information products, a database (5) of user registrations, and a database of an authorized information product index (7) which also contains information referring to a database (10) from which each respective authorized information product can be downloaded; a main server computer (2) controlling said databases and having communication and processing means capable of receiving requests for registration of new users, of generating unique encryption keys for each such user, and of entering such registrations into said user database (5); communication and processing means that can enable downloads from a database (10) of authorized information products to a registered user's client computer (1), so that said information products are encrypted with the encryption key associated with said user before they are stored on said client computer (1); and communication and processing means capable of performing corresponding updates in said database (4) of authorized downloads and in a corresponding encrypted list of authorized information products on said user's client computer (1). 2. Computer system according to claim 1, characterized in that it further comprises a database of offered and requested information products (6), and where said main server computer (2) includes communication and processing means that are able to receive information about offered and requested information products and to enter such information into the aforementioned database of offered and requested information products (6). 3. Computer system according to claim 1 or 2, characterized in that it further comprises a database (3) with registrations of unauthorized downloads of information products and a database with an unauthorized information product index (8) which also contains information referring to a database (11) which is accessible over a computer network (9) and from which each respective Unauthorized Information Product may be downloaded; and where said main server computer (2) comprises communication and processing means capable of accessing network resources (11), searching for unauthorized information products, indexing these and registering said indexes in said database of unauthorized information product indexes (8); communication and processing means which can enable downloads from a database (11) of unauthorized information products to a registered user's client computer (1), so that said information products are encrypted with the encryption key associated with said user before they are stored on said client computer (1); and communication and processing means capable of making corresponding updates in said database (3) of unauthorized downloads and an encrypted list of unauthorized information products on said user's client computer (1). 4. Computer system according to one of the preceding claims, characterized in that it further comprises means for coordinating downloads to two different client computers (1) so that an information product that is downloaded to the first client computer (1) and stored there in a uniquely encrypted form is deleted from a list of information products associated with it the second client computer (1) in a database with lists of information products (3, 4), and that an information product that is downloaded to the second client computer (1) and stored there in a uniquely encrypted form is deleted from a list of information products associated with it the first client computer (1) in a database of lists of information products (3,4). 5. Computer system according to one of the preceding claims, characterized in that it further comprises means for verifying that a user using a client computer (1) is authorized to download an information product from a database (10) of authorized information products to the client computer (1) in a way that ensures that said information product is uniquely encrypted before being stored on the client computer (1). 6. Computer system according to claim 5, characterized in that said means of verification are means for receiving authorized payment information. 7. Computer system according to one of the preceding claims, characterized in that it further comprises means for receiving a unique encryption key from said database of user registrations (5) and distributing this key to a network resource (10) with authorized information products to enable such resources (10) to uniquely encrypt information products before they are downloaded and stored on the client computer (1). 8. Computer system according to one of the preceding claims, characterized in that it further comprises means for receiving a unique encryption key from said database of user registrations (5), downloading the information product from a network resource (10, 11), encrypting the information product and forwarding the information product to a client computer (1). 9. Computer system according to one of the preceding claims, characterized in that some or all of the aforementioned computer-based databases (3, 4, 5, 6, 7, 8) are integrated parts of the computer system (2). 10. Computer system according to one of the preceding claims, characterized in that it further includes means for presenting information contained in said database of offered and requested information products (6), said database with index of authorized information products (7) and, if included, said database with index of unauthorized information products (8) ) in a form that can be read by a browser, using protocols such as HTML, XML, HTTP. 11. Computer system according to one of the preceding claims, characterized in that it further includes means for allowing searches for information stored in said database of offered and requested information products (6), said database with index of authorized information products (7) and, if included, said database with index of unauthorized information products (8). 12. Computer system according to one of the preceding claims, characterized in that the various means which make up the computer system (2) are software modules which are stored on computer storage means and which comprise instructions which, when processed on one or more processor units, enable said computer system to work. 13. Computer system according to one of the preceding claims, characterized in that said information products are digitally encoded music. 14. Computer system according to one of the preceding claims, characterized in that said music is encoded as MP3 files. 15. Computer system according to one of claims 1-12, characterized in that said information products are images or video. 16. Computer system according to one of claims 1 - 12, characterized in that said information product is a digital multimedia presentation. 17. Computer program comprising instructions which, when processed by one or more processor units in a computer system, enable said computer system to work in accordance with one of claims 1 to 16. 18. Computer program according to claim 17, stored on a computer-readable medium. 19. Computer program according to claim 17, carried on an electrical or optical information-carrying signal. 20. Computer client system for handling secure distribution and access to information products, characterized in that it includes means for accessing information products available on network resources (10, 11) available over a computer network (9), means for downloading such information products, means for storing said information products as uniquely encrypted files, means for encrypting and storing a list of each downloaded and encrypted information product file, a stored encryption/decryption key, and means for accessing said encrypted information product using said key, provided that said information product is contained in said encrypted list of downloaded information products. 21. Computer client system according to claim 20, characterized in that it further comprises means which use said key to encrypt said information product as it is downloaded and stored. 22. Computer client system according to claim 20 or 21, characterized in that it further includes means for accessing information in a database of offered and requested information products (6). 23. Computer client system according to one of claims 20 - 22, characterized in that it further comprises means for registering offered or requested information products in a database of offered or requested information products (6). 24. Computer client system according to one of claims 20-23, characterized in that it further comprises means for accessing information in a database with an information product index (7, 8). 25. Computer client system according to one of claims 20 - 24, characterized in that it further comprises means for deleting an entry in said encrypted list of downloaded and encrypted information product files when a new information product file is downloaded in exchange for the information product that is deleted. 26. Computer client system according to one of claims 20 - 25, characterized in that it further comprises means for extracting unique hardware information from hardware that forms part of the client system and making said information available for inclusion in the encrypted information product files. 27. Computer client system according to one of claims 20 - 26, characterized in that it further comprises means for extracting unique software information from software that forms part of the client system and making said information available for inclusion in the encrypted information product files. 28. Computer client system according to one of claims 26 or 27, characterized in that it further comprises means for determining whether information extracted from hardware or software and included in an encrypted information product file does not correspond to such information on the client system, and if so prevent decryption of said information product file. 29. Computer client system according to one of claims 20 - 28, characterized in that said encryption/decryption key is contained in the client's software code and not readily available to a user of the client system. 30. Computer client system according to one of claims 20 - 29, characterized in that said encrypted list of each downloaded information product is in a proprietary format which is more difficult to decrypt than standard text files. 31. Computer client system according to one of claims 20 - 30, characterized in that it further comprises means for downloading information using FTP or HTTP. 32. Computer client system according to one of claims 20 - 31, characterized in that it further comprises means for displaying information formatted according to HTML or XML. 33. Computer client system according to one of claims 20 - 32, characterized in that the various means that make up the computer client system (1) are software modules which are stored on computer storage means and which comprise instructions which, when processed by one or more processor units, enables said computer-client system to work. 34. Computer client system according to one of claims 20 - 33, characterized in that said information product is digitally encoded music. 35. Computer client system according to claim 34, characterized in that said music is encoded as MP3 files. 36. Computer client system according to one of claims 20 - 33, characterized in that said information product is images or video. 37. Computer client system according to one of claims 20 - 33, characterized in that said information product is a digital multimedia presentation. 38. Computer program comprising instructions which, when processed by one or more processor units in a computer system, enable said computer system to work in accordance with one of claims 20 to 37. 39. Computer program according to claim 38, stored on a computer-readable medium. 40. Computer program according to claim 38, carried on an electrical or optical information-carrying signal. 41. Computer server system for secure distribution of information products, characterized in that it comprises a database of authorized information products, communication and processing means capable of transferring an index of such information products to a main server computer (2) for registration in a database with an index of authorized information products (7), and means for allowing downloading of information products from said database for storage in a uniquely encrypted form on client computers (1) upon receipt of a confirmation from said main server computer (2) that said downloading is authorized. 42. Computer server system according to claim 41, characterized in that it further includes means for temporarily receiving a unique key for encryption of information products before downloading of said product is permitted. 43. Computer server system according to claim 42, characterized in that it further comprises means for receiving unique hardware and/or software information from a client computer (1) requesting a download, to include said information in the header of an information product file. 44. Computer server system according to one of claims 41 - 43, characterized in that said main server (2) is a computer system according to one of claims 1-15. 45. Computer-server system according to one of claims 41-44, characterized in that said client computers (1) are computer-client systems according to one of claims 19-36. 46. Computer program comprising instructions which, when processed by one or more processor units in a computer system, enable said computer system to operate in accordance with one of claims 41 to 45. 47. Computer program according to claim 46, stored on a computer-readable medium. 48. Computer program according to claim 46, carried on an electrical or optical information-carrying signal. 49. Procedure for distributing information products in a computer network, characterized in that it comprises receiving at a main server computer (2), from a unique client computer (1), a request for an information product contained in an index of information products stored in a database (7, 8); to ensure that said unique client computer (1) can be associated with a user of the client computer (1), and that said user is registered in a database of user registrations, to find said information product on a network resource (10, 11) to initiate the download of said information product from said network resource (10, 11) to said client computer (1), ensuring that said information product is uniquely encrypted using a key associated with the user of said client computer (1) before the information product. stored on said client computer, to enter a reference to said information product in a database (4) of registered downloads of information products, and to ensure that a corresponding reference is entered into an encrypted list of information products stored on said client computer (1). 50. Method according to claim 49, characterized in that it further includes to check whether access to said information product requires authorization, and to attempt to obtain a verification of such authorization before said download is initiated. 51. Method according to claim 50, characterized in that the verification of authorization is a confirmation received from a computer-based payment system indicating that payment has been made for said information product. 52. Method according to claim 50, characterized in that the verification of authorization is a confirmation received from the client computer (1) that said information product has been acquired in exchange for another information product that already exists on the client computer (1) as part of a coordinated download of said other information product to another unique client computer (1), after which the method further comprises to remove a reference to said second information product from said list of information products stored in said database (4), to remove a reference to the first information product from a corresponding list of information products stored in said database (4) and associated with the user of said second client computer (1), and to ensure that corresponding removals are made from encrypted lists of information products stored on the respective client computers. 53. Method according to one of claims 49 - 52, characterized by said information product is digitally encoded music. 54. Method according to claim 53, characterized in that said music is encoded as MP3 files. 55. Method according to one of claims 49 - 52, characterized in that said information product is images or video. 56. Method according to one of claims 49 - 52, characterized in that said information product is a digital multimedia presentation. 57. Method according to one of claims 49 - 56, characterized in that the steps in the method are performed automatically in a computer system under the control of instructions stored in the form of a computer program on a computer-readable storage medium. 58. Computer program comprising instructions which, when processed by one or more processor units in a computer system, enable said computer system to carry out the method according to one of claims 49 to 57. 59. Computer program according to claim 58, stored on a computer-readable medium. 60. Computer program according to claim 58, carried on an electrical or optical information-carrying signal.