Hyphanet
Hyphanet is a peer-to-peer platform for censorship-resistant, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free software for publishing and communicating on the Web without fear of censorship.Taylor, Ian J. From P2P to Web Services and Grids: Peers in a Client/Server World. London: Springer, 2005. Both Freenet and some of its associated tools were originally designed by Ian Clarke, who defined Freenet's goal as providing freedom of speech on the Internet with strong anonymity protection.
The distributed data store of Hyphanet is used by many third-party programs and plugins to provide microblogging and media sharing, anonymous and decentralised version tracking, blogging, a generic web of trust for decentralized spam resistance, Shoeshop for using Freenet over sneakernet, and many more.
History
The origin of Hyphanet can be traced to Ian Clarke's student project at the University of Edinburgh, which he completed as a graduation requirement in the summer of 1999. Ian Clarke's resulting unpublished report "A distributed decentralized information storage and retrieval system" provided foundation for the seminal paper written in collaboration with other researchers, "Freenet: A Distributed Anonymous Information Storage and Retrieval System". According to CiteSeer, it became one of the most frequently cited computer science articles in 2002.Name and continuity
The project was known as Freenet for most of its history and was renamed to Hyphanet in 2023. Academic and technical literature published before the rename generally refers to the system as Freenet.Hyphanetcan provide anonymity on the Internet by storing small encrypted snippets of content distributed on the computers of its users and connecting only through intermediate computers which pass on requests for content and sending them back without knowing the contents of the full file. This is similar to how routers on the Internet route packets without knowing anything about files except Hyphanethas caching, a layer of strong encryption, and no reliance on centralized structures. This allows users to publish anonymously or retrieve various kinds of information.
Release history
Hyphanet has been under continuous development since 2000.Freenet 0.7, released on 8 May 2008, is a major re-write incorporating a number of fundamental changes. The most fundamental change is support for darknet operation. Version 0.7 offered two modes of operation: a mode in which it connects only to friends, and an opennet-mode in which it connects to any other Freenet user. Both modes can be run simultaneously. When a user switches to pure darknet operation, Freenet becomes very difficult to detect from the outside. The transport layer created for the darknet mode allows communication over restricted routes as commonly found in mesh networks, as long as these connections follow a small-world structure. Other modifications include switching from TCP to UDP, which allows UDP hole punching along with faster transmission of messages between peers in the network.
Freenet 0.7.5, released on 12 June 2009, offers a variety of improvements over 0.7. These include reduced memory usage, faster insert and retrieval of content, significant improvements to the FProxy web interface used for browsing freesites, and a large number of smaller bugfixes, performance enhancements, and usability improvements. Version 0.7.5 also shipped with a new version of the Windows installer.
As of build 1226, released on 30 July 2009, features that were written include significant security improvements against both attackers acting on the network and physical seizure of the computer running the node.
As of build 1468, released on 11 July 2015, the Freenet core stopped using the db4o database and laid the foundation for an efficient interface to the Web of Trust plugin which provides spam resistance.
Freenet has always been free software, but until 2011 it required users to install Java. This problem was solved by making Freenet compatible with OpenJDK, a free and open source implementation of the Java Platform.
On 11 February 2015, Freenet received the SUMA-Award for "protection against total surveillance".
Features and user interface
Hyphanet served as the model for the Japanese peer to peer file-sharing programs Winny, Share and Perfect Dark, but this model differs from p2p networks such as Bittorrent and emule. Freenet separates the underlying network structure and protocol from how users interact with the network; as a result, there are a variety of ways to access content on the Freenet network. The simplest is via FProxy, which is integrated with the node software and provides a web interface to content on the network. Using FProxy, a user can browse freesites. The web interface is also used for most configuration and node management tasks. Through the use of separate applications or plugins loaded into the node software, users can interact with the network in other ways, such as forums similar to web forums or Usenet or interfaces more similar to traditional P2P "filesharing" interfaces.While Freenet provides an HTTP interface for browsing freesites, it is not a proxy for the World Wide Web; Freenet can be used to access only the content that has been previously inserted into the Freenet network. In this way, it is more similar to Tor's onion services than to anonymous proxy software like Tor's proxy.
Hyphanet's focus lies on free speech and anonymity. Because of that, Hyphanet acts differently at certain points that are related to the anonymity part. Hyphanet attempts to protect the anonymity of both people inserting data into the network and those retrieving data from the network. Unlike file sharing systems, there is no need for the uploader to remain on the network after uploading a file or group of files. Instead, during the upload process, the files are broken into chunks and stored on a variety of other computers on the network. When downloading, those chunks are found and reassembled. Every node on the Freenet network contributes storage space to hold files and bandwidth that it uses to route requests from its peers.
As a direct result of the anonymity requirements, the node requesting content does not normally connect directly to the node that has it; instead, the request is routed across several intermediaries, none of which know which node made the request or which one had it. As a result, the total bandwidth required by the network to transfer a file is higher than in other systems, which can result in slower transfers, especially for infrequently accessed content.
Since version 0.7, Hyphanet has offered two different levels of security: opennet and darknet. With opennet, users connect to arbitrary other users. With darknet, users connect only to "friends" with whom they previously exchanged public keys, named node-references. Both modes can be used together.
Content
Hyphanet's founders argue that true freedom of speech comes only with true anonymity and that the beneficial uses of Hyphanet outweigh its negative uses. Their view is that free speech, in itself, is not in contradiction with any other consideration—the information is not the crime. Hyphanet attempts to remove the possibility of any group imposing its beliefs or values on any data. Although many states censor communications to different extents, they all share one commonality in that a body must decide what information to censor and what information to allow. What may be acceptable to one group of people may be considered offensive or even dangerous to another. In essence, the purpose of Freenet is to ensure that no one is allowed to decide what is acceptable.Reports of Freenet's use in authoritarian nations is difficult to track due to the very nature of Freenet's goals. One group, Freenet China, used to introduce the Freenet software to Chinese users starting from 2001 and distribute it within China through e-mails and on disks after the group's website was blocked by the Chinese authorities on the mainland. It was reported that in 2002 Freenet China had several thousand dedicated users. However, Hyphanet opennet traffic was blocked in China around the 2010s.
Technical design
The Hyphanet file sharing network stores documents and allows them to be retrieved later by an associated key, as is now possible with protocols such as HTTP. The network is designed to be highly survivable. The system has no central servers and is not subject to the control of any one individual or organization, including the designers of Freenet. The codebase size is over 192,000 lines of code. Information stored on Hyphanet is distributed around the network and stored on several different nodes. Encryption of data and relaying of requests makes it difficult to determine who inserted content into Hyphanet, who requested that content, or where the content was stored. This protects the anonymity of participants, and also makes it very difficult to censor specific content. Content is stored encrypted, making it difficult for even the operator of a node to determine what is stored on that node. This provides plausible deniability; which, in combination with request relaying, means that safe harbor laws that protect service providers may also protect Hyphanet node operators. When asked about the topic, Freenet developers defer to the EFF discussion which says that not being able to filter anything is a safe choice.Distributed storage and caching of data
Like Winny, Share and Perfect Dark, Hyphanet not only transmits data between nodes but actually stores them, working as a huge distributed cache. To achieve this, each node allocates some amount of disk space to store data; this is configurable by the node operator, but is typically several GB.Files on Hyphanet are typically split into multiple small blocks, with duplicate blocks created to provide redundancy. Each block is handled independently, meaning that a single file may have parts stored on many different nodes.
Information flow in Hyphanet is different from networks like eMule or BitTorrent; in Freenet:
- A user wishing to share a file or update a freesite "inserts" the file "to the network"
- After "insertion" is finished, the publishing node is free to shut down, because the file is stored in the network. It will remain available for other users whether or not the original publishing node is online. No single node is responsible for the content; instead, it is replicated to many different nodes.
The key disadvantage of the storage method is that no one node is responsible for any chunk of data. If a piece of data is not retrieved for some time and a node keeps getting new data, it will drop the old data sometime when its allocated disk space is fully used. In this way Hyphanet tends to 'forget' data which is not retrieved regularly.
While users can insert data into the network, there is no way to delete data. Due to Freenet's anonymous nature the original publishing node or owner of any piece of data is unknown. The only way data can be removed is if users don't request it.