Protocol encryption (PE), Message stream encryption (MSE), or Protocol header encrypt (PHE)^[1] are related features of some peer-to-peer file-sharing clients, including BitTorrent. They attempt to make traffic harder to identify by third parties including internet service providers (ISPs). A peer-to-peer (or P2P) computer network is a network that relies on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively few servers. ... See Shared resource for the conventional meaning of file sharing File sharing is the practice of making files available for other users to download over the Internet and smaller networks. ... Comparison of BitTorrent software Comparison of eDonkey software Comparison of Gnutella software Comparison of G2 software Anonymous peer-to-peer Categories: | ... This article is about the protocol. ... “ISP” redirects here. ...

MSE/PE is implemented in Azureus, BitComet, BitTornado, KTorrent, Mainline (incoming only), µTorrent, and rTorrent. PHE was implemented in old versions of BitComet. Similar protocol obfuscation is supported in up-to-date versions of some other (non-BitTorrent) systems including eMule. Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ... BitComet (originally named SimpleBT client from versions 0. ... BitTornado in Ubuntu Linux BitTornado is a BitTorrent client. ... KTorrent is a BitTorrent client written in C++ for KDE using the Qt user interface toolkit. ... This article is about Bittorrent clients in general. ... µTorrent (also microTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... rTorrent is a text-based ncurses BitTorrent client written in C++, based on the libTorrent libraries for UNIX (Rakshasas own, not the sourceforge libtorrent), with a focus on high performance and good code. ... Obfuscation refers to the concept of concealing the meaning of communication by making it more confusing and harder to interpret. ... eMule is a peer-to-peer file sharing application for Microsoft Windows. ...

Purpose

Peer-to-peer file-sharing traffic makes up more than a third of total internet traffic.^[2] Some ISPs deal with this traffic by increasing their capacity whilst others use specialised systems to throttle (i.e. slow down) BitTorrent traffic. Obfuscation and encryption make traffic harder to detect and therefore harder to throttle. These systems are not designed to provide anonymity. “Anonymous” redirects here. ...

History

Early approach

Protocol header encryption (PHE) was conceived by RnySmile and first implemented in BitComet version 0.60 on 8 September 2005. Some software like IPP2P claims BitComet traffic is detectable even with PHE.^[3] PHE is detectable because only part of the stream is encrypted. Since there are no open specifications to this protocol implementation the only possibility to support it in other clients would have been via reverse engineering. BitComet (originally named SimpleBT client from versions 0. ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Reverse engineering (RE) is the process of taking something (a device, an electrical component, a software program, etc. ...

Development of MSE/PE

In late January 2006 the Azureus developers decided to design and simultaneously implement a new, open protocol obfuscation method, called message stream encryption (MSE). It was included in Azureus CVS snapshot 2307-B29 on 19 January 2006.^[4] Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ... is the 19th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

This first draft was heavily criticized since it lacked several key features. After negotiations between different BitTorrent developers a new proposal was written and then implemented into the Azureus and µTorrent betas within days. The developers were ludde, uau, The 8472, Parg and Nolar. In µTorrent, the new protocol was called protocol encryption (PE). Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ... µTorrent (also microTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... Ludvig Strigeus (ludde) is a Swedish programmer best known for writing the BitTorrent client µTorrent. ... Paul Gardner (parg) is a British programmer and one of the main developers of the Azureus bittorrent client. ...

MSE/PE in BitTorrent client versions

Azureus supports the final spec since 25 January 2006 (CVS snapshot 2307-B33)^[5]. Azureus version 2.4.0.0 was released 10 February 2006, and was the first stable version of a client to support MSE/PE. However, glitches in Azureus' implementation resulted in improperly encrypted pieces that failed hash checking. The glitches were rectified as of version 2.4.0.2.^[6] Azureus is a Java-based BitTorrent client, with support for I2P and Tor anonymous communication protocols. ... is the 25th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 41st day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

µTorrent premiered MSE/PE 4 days after Azureus with beta 1.4.1 build 407.^[7]. µTorrent version 1.5 (build 436) was released on 7 March 2006; it was the first stable version of µTorrent with PE. µTorrent (also microTorrent or uTorrent) is a freeware proprietary BitTorrent client for Microsoft Windows written in C++[1] and localized for many different languages. ... is the 66th day of the year (67th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

BitComet version 0.63 was released 7 March 2006. It removed the old protocol header encryption and implemented the new MSE/PE to be compatible with Azureus and µTorrent.^[8] is the 66th day of the year (67th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

KTorrent implemented MSE/PE in SVN version 535386^[9] on April 29, 2006.^[10] KTorrent is a BitTorrent client written in C++ for KDE using the Qt user interface toolkit. ... is the 119th day of the year (120th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

Mainline supports MSE/PE since version 4.9.2-beta on May 2, 2006.^[11] This article is about Bittorrent clients in general. ... May 2 is the 122nd day of the year in the Gregorian calendar (123rd in leap years). ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

BitTornado supports MSE/PE as of build T-0.3.18. As of January 5, 2007, this build is still marked "experimental" on the Download page.^[12] BitTornado in Ubuntu Linux BitTornado is a BitTorrent client. ... is the 5th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ...

rTorrent supports MSE/PE as of rTorrent-0.7.0.^[13] rTorrent is a text-based ncurses BitTorrent client written in C++, based on the libTorrent libraries for UNIX (Rakshasas own, not the sourceforge libtorrent), with a focus on high performance and good code. ...

Deluge supports MSE/PE as of Deluge-0.5.1.^[14] Deluge is a BitTorrent client, created using Python and GTK+ (through PyGTK). ...

Operation

The BitComet PHE method used in versions 0.60 to 0.62 is neither published, nor is it compatible with MSE/PE.

MSE/PE uses a D-H key exchange combined with the infohash of the torrent to establish the key, then it uses RC4 to encrypt the data. The D-H key exchange helps to minimize the risk of passive listeners, and the infohash helps avoid man-in-the-middle attacks. RC4 is chosen for its speed. The first kilobyte of the RC4 output is discarded to prevent a particular attack. Diffie-Hellman (D-H) key exchange is a cryptographic protocol that allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel. ... In cryptography, RC4 (also known as ARC4 or ARCFOUR) is the most widely-used software stream cipher and is used in popular protocols such as Secure Sockets Layer (SSL) (to protect Internet traffic) and WEP (to secure wireless networks). ... It has been suggested that Mafia Fraud Attack be merged into this article or section. ... In cryptography, RC4 (also known as ARC4 or ARCFOUR) is the most widely-used software stream cipher and is used in popular protocols such as Secure Sockets Layer (SSL) (to protect Internet traffic) and WEP (to secure wireless networks). ...

The specification allows the users to choose between encrypting the headers only or the full connection. Encrypting the full connection provides more obfuscation but uses more CPU time. However, only Azureus and µTorrent beta 1.4.1 build 413 or older lets the user choose. All other clients default to full encryption.

To ensure compatibility with other clients that don't support this specification, users may also choose whether unencrypted incoming or outgoing connections are still allowed.

All supported clients will enable encryption automatically if they receive an encrypted incoming connection even if outgoing encryption is disabled.

Supported clients propagate the fact that they have MSE/PE enabled through PEX and DHT. Other clients will then connect to them with encryption even if outgoing encryption is disabled. This article or section is not written in the formal tone expected of an encyclopedia article. ... Distributed hash tables (DHTs) are a class of decentralized distributed systems that provide a lookup service similar to a hash table: (name, value) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given name. ...

Security

The estimated strength of the encryption corresponds to about 60–80 bits for common symmetrical ciphers^[15]. This is quite low for today's standards but one has to keep in mind that this protocol wasn't designed as a secure transport protocol but as a fast and efficient obfuscation method. AES was proposed as the encryption method but not adopted because it consumed too much CPU time and the required D-H keys to achieve a security equal to AES would have been much bigger or require elliptic curve cryptography, making the handshake more expensive in terms of used CPU time. In cryptography, the Advanced Encryption Standard (AES), also known as Rijndael, is a block cipher adopted as an encryption standard by the U.S. government. ... Diffie-Hellman (D-H) key exchange is a cryptographic protocol that allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel. ... Elliptic curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ...

Effectiveness

Many ISPs are now using more sophisticated measures (e.g. pattern/timing analysis or categorizing ports based on side-channel data) to detect BitTorrent traffic. This means that even encrypted BitTorrent traffic can be throttled. However, whilst most ISPs use the simpler, less costly, methods to identify and throttle BitTorrent, the current solution remains extremely effective.

A fatal flaw where encryption doesn't matter

The Sandvine net appliance uses a different approach to throttling BitTorrent traffic that makes seeding impossible, by sending counterfeit protocol hangup packets. Multiple secure VPNs between clients have become necessary (in order for the Sandvine hack to be disabled). Sandvine Incorporated (TSX: SVC, AIM: SAND), is a networking equipment company based in Waterloo, Ontario, Canada. ... A Virtual Private Network, or VPN, is a private communications network usually used within a company, or by several different companies or organizations, communicating over a public network. ...

Using Tor as a secure tunnel (as it is not a true VPN) to exit one's traffic from one's ISP is the only semi-workable solution at the moment. It must be assumed that Sandvine throttles Tor traffic less severely than BitTorrent traffic.

This link gives a more technical explaination of the above

• http://torrentfreak.com/comcast-throttles-bittorrent-traffic-seeding-impossible/
• Countermeasures are possible: http://hireme.geek.nz/sandvine.html

Criticism

Bram Cohen, the inventor of BitTorrent, opposed adding encryption to the BitTorrent protocol. Cohen stated he was worried that encryption could create incompatibility between clients. He also stressed the point that the majority of ISPs don't block the torrent protocol. Cohen wrote "I rather suspect that some developer has gotten rate limited by his ISP, and is more interested in trying to hack around his ISP's limitations than in the performance of the internet as a whole".^[16] Many BitTorrent community users responded strongly against Cohen's accusations.^[17] Cohen later added the ability to receive encrypted connections but not send out encrypted data on his Mainline client.^[18] Bram Cohen (born 1975) is an American computer programmer, best known as the author of the peer-to-peer (P2P) protocol BitTorrent, as well as the first file sharing program to use the protocol. ... This article is about the protocol. ... BitTorrent is a computer program developed by Bram Cohen and BitTorrent, Inc. ...

BBC claims

In 2006, a Newsnight episode claimed that the use of encrypted BitTorrent helps terrorists and paedophiles because any increase in encrypted traffic makes it more difficult for law enforcement to monitor the Internet^{[citation needed]}. Newsnight is a British daily news analysis, current affairs and politics programme broadcast between 22:30 and 23:20 on weekdays on BBC Two. ...

Many BitTorrent users were outraged and complained.^[19] BBC stood by its claim about paedophiles and terrorists, but it did admit that such references are often used by others as a way to sell copy, and that traditional media like television are under threat from new media like BitTorrent.^{[citation needed]} BBC apologised for saying that peer to peer file sharing was "theft"^[20]

As the UK does not have a program like Australia's ABC Mediawatch -- there is no neutral entity to challenge the quality of journalism in this case. It must also be pointed out that probably some 5% of global BitTorrent traffic (where the end content is in English) may indeed by BBC programmes. ^{[citation needed]}

Notes and references

1. ^ It is usually referred to as the more correct protocol header encryption instead.
2. ^ Wired: The Bittorrent Effect (2007-05-30).
3. ^ IPP2P homepage - News (2006-01-04).
4. ^ CVS Snapshot Azureus2307-B29.jar has been released ! (2006-01-19).
5. ^ CVS Snapshot Azureus2307-B33.jar has been released ! (2006-01-25).
6. ^ Azureus : Java BitTorrent Client - Changelog.
7. ^ µTorrent 1.4.2 beta 435 (2006-01-29).
8. ^ BitComet Client Release Notes (2006-03-07).
9. ^ The SVN server is at svn://anonsvn.kde.org/home/kde/trunk/extragear/network/ktorrent
10. ^ Encryption has been added ! (2006-04-29).
11. ^ Version Notes. BitTorrent (2006-05-02).
12. ^ BitTornado T-0.3.18 (2007-01-05).
13. ^ Announcement of rTorrent-0.7.0 (2006-12-13).
14. ^ Deluge 0.5.1 Release Announcement (2007-06-11).
15. ^ RFC 3526 chapter 8.
16. ^ Cohen, Bram (2006-01-29). Obfuscating BitTorrent.
17. ^ Debate over Protocol Encryption.
18. ^ BitTorrent Mainline Version History (2006-10-15).
19. ^ Feedback - February 2006 (2). BBC News.
20. ^ Livingstone, Adam (2006-02-28). A bit of BitTorrent bother. BBC News.

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... is the 150th day of the year (151st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 4th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 19th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 25th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 29th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 66th day of the year (67th in leap years) in the Gregorian calendar. ... In computing, Subversion (SVN) is a version control system (VCS) initiated in 2000 by CollabNet Inc. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 119th day of the year (120th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... May 2 is the 122nd day of the year in the Gregorian calendar (123rd in leap years). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... is the 5th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 347th day of the year (348th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... is the 162nd day of the year (163rd in leap years) in the Gregorian calendar. ... Bram Cohen (born 1975) is an American computer programmer, best known as the author of the peer-to-peer (P2P) protocol BitTorrent, as well as the first file sharing program to use the protocol. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 29th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 288th day of the year (289th in leap years) in the Gregorian calendar. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... February 28 is the 59th day of the year in the Gregorian calendar. ... BBC News is the department within the BBC responsible for the corporations news-gathering and production of news programmes on BBC television, radio and online. ...

External links

• Description on the official Azureus wiki
• ISPs that shape BitTorrent on the official Azureus wiki
• "BitTorrent End to End Encryption and Bandwidth Throttling - Part I" (Interview with µTorrent developers by Slyck News)
• "BitTorrent End to End Encryption and Bandwidth Throttling - Part II" -(Interview with Azureus developers)
• "BitTorrent and End to End Encryption" -(Slashdot)