Free communications on the Freenet network.

Cooling the Trail with Frost

Frost is a Freenet tool that provides a collection of features such as newsreading and message boards [2]. The Frost utility comes in a ZIP archive. After unpacking in a separate directory, you can launch Frost at the command line by entering sh

The first time you launch Frost, it asks you for your Freenet version and a pseudonym. Frost links the pseudonym with its own public key, which others can uniquely identify even if a third party were to choose the same pseudonym. For example, a flog author can publish her pseudonym and key on her Freesite. Frost users can then be certain that the pseudonym belongs to the flog author. More pseudonyms can be created later as needed.

A user who wants to post a message can choose a pseudonym under which to publish – or opt to do without one. Frost displays a splash screen on launch that threatens to send your personal details to the secret service, which is attributable to the developer's warped sense of humor, but this dire warning is nothing to worry about.

In typical newsreader style, Frost divides the main window into three panels (see Figure 5). Links in forums you subscribe to are displayed in a directory tree: Messages from the selected forum are shown top right; below this you can see the text for the selected message.Some messages are fairly long because Frost users tend to use full-page quotes in their responses. Because the source they are quoting may not be accessible on Freenet, the quote often contains the whole message to preserve the original context.

Figure 5: Frost offers similar mass communication features to Usenet but with pseudonym-based authentication. Participants can thus discuss controversial topics without disclosing their real names but can also be sure that their contributions are uniquely distinguishable and impossible to manipulate.

The forum area is located in a tab, with separate tabs for uploads and downloads and a simple file sharing mechanism. Above these tabs are buttons for configuring Frost and organizing the forums you subscribe to. The most import button is the one with the globe icon. It opens an overview that lets you select and subscribe to known forums.

Publishing Pseudonyms

A column labeled Sig appears along with the forum. For messages posted by users with pseudonyms, the Sig column contains a note on the user's trustworthiness. It is up to you who you trust. The buttons above the list of messages let you specify the degree of trust in a pseudonym. This feature is useful because you can configure the reader to show you messages as of a certain level of trustworthiness. The pseudonyms start with an unknown level of trust (CHECK). BAD is the right setting for trolls, and GOOD for more pleasant Freenet inhabitants. OBSERVE is somewhere between CHECK and GOOD.

Messages can contain references to other forums, Freenet keys, or file attachments. Frost lists attachments at the end of the message, and it displays Freenet keys in the text as hyperlinks. Users can right-click a link to add it to the Download tab.

Freenet Keys

Users or client programs use file keys to access files on Freenet. Freenet distinguishes between the different kinds of file keys that are suitable for various purposes.

Content Hash Keys (CHKs)

The hash is a fingerprint of the file content. If you want to request a document, you need Document-Key and Options to decrypt the file. Because the key is more or less uniquely linked to the file content via the fingerprint, it is practically impossible to modify the file content without the changes being noticed. CHKs are thus the backbone of Freenet.

Signed Subspace Keys (SSKs)

Like CHKs, Document Keys and Options are also used by the requesting entity to decrypt the file content, which is also digitally signed. The requester can use the Public Key to check the signature.

The SSK creator can assign any Name to differentiate between documents. Because nobody can change the content of a file posted on Freenet, not even the key originator, a version number has been introduced. The key originator can increment the version number and thus practically create a new key under which a modified (or completely new) file can be published.

Keyword Signed Keys (KSKs)

KSKs are the simplest and least secure keys on Freenet. The Name can be assigned freely with one or two restrictions, and it is not related in any way to the file content. The disadvantage is that multiple users can assign the same name to different file content, thus causing collisions and inconsistencies.

Updateable Subspace Keys (USKs)

USKs are similar to SSKs. Their elements are identical, except for the Version number, which serves the same purpose as in the SSK, except that the Freenet node will automatically find the latest version of the USK.

Basis for Extensions

Freesites and Frost are just two examples of applications based on Freenet. Some other Freenet applications include the Freemail mail tool and the Thaw file sharing utility.

Work is in progress on other applications, such as an NNTP gateway or adaptations of version control systems such as Mercurial or Arch [3]. A streaming mechanism is on the map for a future version of Freenet.

The Freenet node also includes an interface for plugins and a network interface for client programs. Developers are free to extend the model and integrate it with existing programs.

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