Anonymous remailer
Encyclopedia
An anonymous remailer is a server
Server (computing)
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

 computer which receives messages with embedded instructions on where to send them next, and which forwards them without revealing where they originally came from. There are Cypherpunk anonymous remailer
Cypherpunk anonymous remailer
A cypherpunk anonymous remailer is a Type I anonymous remailer that takes messages encrypted with PGP or GPG, or in some cases in plain text, and forwards them removing any identifying information from the header.-Sending a Cypherpunk Message:...

s, Mixmaster anonymous remailer
Mixmaster anonymous remailer
Mixmaster is a Type II anonymous remailer which sends messages in fixed-size packets and reorders them, preventing anyone watching the messages go in and out of remailers from tracing them. Mixmaster was originally written by Lance Cottrell, and was maintained by Len Sassaman Peter Palfrader is the...

s, and nym servers, among others which differ in how they work, in the policies they adopt, and in the type of attack on anonymity of email they can (or are intended to) resist. Remailing as discussed in this article applies to emails intended for particular recipients, not the general public. Anonymity in the latter case is more easily addressed by using any of several methods of anonymous publication
Anonymity
Anonymity is derived from the Greek word ἀνωνυμία, anonymia, meaning "without a name" or "namelessness". In colloquial use, anonymity typically refers to the state of an individual's personal identity, or personally identifiable information, being publicly unknown.There are many reasons why a...

.

Types of remailer

There are several strategies which contribute to making the e-mail so handled (more, or less) anonymous. In general, different classes of anonymous remailers differ with regard to the choices their designers/operators have made. These choices can be influenced by the legal ramifications of operating specific types of remailers.

It must be understood that every data packet traveling on the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 contains the node addresses (as raw IP
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...

 bit strings) of both the sending and intended recipient nodes, and so no data packet can ever actually be anonymous at this level. However, if the IP source address is false, there will be no easy way to trace the originating node (and so the originating entity for the packet). In addition, all standards-based email messages contain defined fields in their headers in which the source and transmitting entities (and Internet nodes as well) are required to be included. However, since most users of email do not have very much technical expertise, the full headers are usually suppressed by mail reading software. Thus, many users have never seen one.

Some remailers change both types of address in messages they forward, and the list of forwarding nodes in email messages as well, as the message passes through; in effect, they substitute 'fake source addresses' for the originals. The 'IP source address' for that packet may become that of the remailer server itself, and within an email message (which is usually several packets), a nominal 'user' on that server. Some remailers forward their anonymized email to still other remailers, and only after several such hops is the email actually delivered to the intended address.

There are, more or less, four types of remailers:
  • Pseudonymous remailer
    Pseudonymous remailer
    A pseudonymous remailer or nym server, as opposed to an anonymous remailer, is an Internet software program designed to allow people to write pseudonymous messages on Usenet newsgroups and send pseudonymous email. Unlike purely anonymous remailers, it assigns its users a user name, and it keeps a...

    s

A Pseudonymous remailer, simply takes away the email address of the sender, gives a pseudonym to the sender and sends the message to the intended recipient (that can be answered via that remailer).
  • Cypherpunk
    Cypherpunk
    A cypherpunk is an activist advocating widespread use of strong cryptography as a route to social and political change.Originally communicating through the Cypherpunks electronic mailing list, informal groups aimed to achieve privacy and security through proactive use of cryptography...

     remailers, also called type I

A Cypherpunk remailer
Cypherpunk anonymous remailer
A cypherpunk anonymous remailer is a Type I anonymous remailer that takes messages encrypted with PGP or GPG, or in some cases in plain text, and forwards them removing any identifying information from the header.-Sending a Cypherpunk Message:...

 sends the message to the recipient stripping away the sender address on it. You can not answer a message sent via a Cypherpunk remailer. You can usually encrypt the message sent to the remailer, and the remailer will decrypt it and send it to the recipient address hidden inside the encrypted message. In addition, you can chain 2 or 3 remailers, so each remailer can't know who is sending a message to whom. Cypherpunk remailers do not keep logs of transactions.
  • Mixmaster
    Mixmaster anonymous remailer
    Mixmaster is a Type II anonymous remailer which sends messages in fixed-size packets and reorders them, preventing anyone watching the messages go in and out of remailers from tracing them. Mixmaster was originally written by Lance Cottrell, and was maintained by Len Sassaman Peter Palfrader is the...

     remailers, also called type II

Mixmaster remailers require use of a program on your computer to write your messages. Such programs are not supplied as a standard part of most operating systems or mail management systems.
  • Mixminion
    Mixminion
    Mixminion is the standard implementation of the Type III anonymous remailer protocol. Mixminion can send and receive anonymous e-mail.Mixminion uses a mix network architecture to provide strong anonymity, and prevent eavesdroppers and other attackers from linking senders and recipients...

     remailers, also called type III

A Mixminion remailer attempts to address the following challenges in Mixmaster remailers: replies, forward anonymity, replay prevention and key rotation, exit policies, integrated directory servers, dummy traffic. They have been implemented for the Linux and Windows platforms and are currently available. Some implementations are open source.

Traceable remailers

Some remailers establish an internal list of actual senders and invented names such that a recipient can send mail to invented name AT some_remailer.net. When receiving traffic addressed to this user, the server software consults that list, and forwards the mail to the original sender, thus permitting anonymous -- though traceable with access to the list -- two way communication. The famous "penet.fi
Penet remailer
The Penet remailer was a pseudonymous remailer operated by Johan "Julf" Helsingius of Finland from 1993 to 1996. Its initial creation stemmed from an argument in a Finnish newsgroup over whether people should be required to tie their real name to their online communications...

" remailer in Finland did just that for several years. Because of the existence of such lists in this type of remailing server, it is possible to break the anonymity by gaining access to the list(s), by breaking into the computer, asking a court (or merely the police in some places) to order that the anonymity be broken, and/or bribing an attendant. This happened to penet.fi as a result of some traffic passed through it about Scientology
Scientology
Scientology is a body of beliefs and related practices created by science fiction and fantasy author L. Ron Hubbard , starting in 1952, as a successor to his earlier self-help system, Dianetics...

. The Church claimed copyright infringement and sued penet.fi's operator. A court ordered the list be made available. Penet's operator shut it down after destroying its records (including the list) to retain identity
Digital identity
Digital identity is the aspect of digital technology that is concerned with the mediation of people's experience of their own identity and the identity of other people and things...

 confidentiality
Confidentiality
Confidentiality is an ethical principle associated with several professions . In ethics, and in law and alternative forms of legal resolution such as mediation, some types of communication between a person and one of these professionals are "privileged" and may not be discussed or divulged to...

 for its users; though not before being forced to supply the court with the real email addresses of two of its users.

More recent remailer designs use cryptography
Cryptography
Cryptography is the practice and study of techniques for secure communication in the presence of third parties...

 in an attempt to provide more or less the same service, but without so much risk of loss of user confidentiality. These are generally termed nym servers or pseudonymous remailer
Pseudonymous remailer
A pseudonymous remailer or nym server, as opposed to an anonymous remailer, is an Internet software program designed to allow people to write pseudonymous messages on Usenet newsgroups and send pseudonymous email. Unlike purely anonymous remailers, it assigns its users a user name, and it keeps a...

s. The degree to which they remain vulnerable to forced disclosure (by courts or police) is and will remain unclear, since new statutes/regulations and new cryptanalytic developments proceed apace. Multiple anonymous forwarding among cooperating remailers in different jurisdictions may retain, but cannot guarantee, anonymity against a determined attempt by one or more governments, or civil litigators.

Untraceable remailers

If users accept the loss of two-way interaction, identity anonymity can be made more secure.

By not keeping any list of users and corresponding anonymizing labels for them, a remailer can ensure that any message which has been forwarded leaves no internal information behind which can later be used to break identity confidentiality. However, while being handled, messages remain vulnerable within the server (e.g., to Trojan
Trojan horse (computing)
A Trojan horse, or Trojan, is software that appears to perform a desirable function for the user prior to run or install, but steals information or harms the system. The term is derived from the Trojan Horse story in Greek mythology.-Malware:A destructive program that masquerades as a benign...

 software in a compromised server, to a compromised server operator, or to mis-administration of the server), and traffic analysis
Traffic analysis
Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. It can be performed even when the messages are encrypted and cannot be decrypted. In general, the greater the number of messages observed, or even intercepted and...

 comparison of traffic into and out of such a server can suggest quite a lot -- far more than almost any would credit.

The Mixmaster
Mixmaster anonymous remailer
Mixmaster is a Type II anonymous remailer which sends messages in fixed-size packets and reorders them, preventing anyone watching the messages go in and out of remailers from tracing them. Mixmaster was originally written by Lance Cottrell, and was maintained by Len Sassaman Peter Palfrader is the...

 strategy is designed to defeat such attacks, or at least to increase their cost (i.e., to 'attackers') beyond feasibility. If every message is passed through several servers (ideally in different legal and political jurisdictions), then attacks based on legal systems become considerably more difficult, if only because of 'Clausewitzian' friction amongst lawyers, courts, different statutes, organizational rivalries, legal systems, etc. And, since many different servers and server operators are involved, subversion of any (i.e., of either system or operator) becomes less effective also since no one (most likely) will be able to subvert the entire chain of remailers.

Random padding
Padding (cryptography)
-Classical cryptography:Official messages often start and end in predictable ways: My dear ambassador, Weather report, Sincerely yours, etc. The primary use of padding with classical ciphers is to prevent the cryptanalyst from using that predictability to find cribs that aid in breaking the...

 of messages, random delays before forwarding, and encryption of forwarding information between forwarding remailers, increases the degree of difficulty for attackers still further as message size and timing can be largely eliminated as traffic analysis clues, and lack of easily readable forwarding information renders ineffective simple automated traffic analysis algorithms.

Quick Remail Service is an anonymous remailing service for postal mail. You can put your letter you wish to send anonymously in a larger envelope and send it to quickremail.com . They will open your large envelope and mail your letter anonymously.

Web based mailer

There are also web services that will let you send anonymous email messages. These services do not provide the anonymity of real remailers, but they are easier to use. When using a web based anonymous email or anonymous remailer service you should first analyze the reputation of this service, since the service stands in the middle between you and the email recipient.

Using a remailer

If the object is identity anonymity, nothing sent via a remailer can ever include identifying information in content available to an outside observer. Thus, "From: anon(At)remailer.net Hey dude, send me that new comic to 123 Maple Street, Wherever, Country, Postal Code. Thanx" is evidently entirely unsecure. Encrypting such a message with an adequately secure cryptosystem would help, and some remailers are set up to do so. In general cleartext messages are likely to include such information even if inadvertently, and user anonymity when sending cleartext messages is accordingly likely to be lost.

Less obviously, some software (e.g., recent versions of Microsoft Office
Microsoft Office
Microsoft Office is a non-free commercial office suite of inter-related desktop applications, servers and services for the Microsoft Windows and Mac OS X operating systems, introduced by Microsoft in August 1, 1989. Initially a marketing term for a bundled set of applications, the first version of...

 components -- Microsoft Word, Microsoft Excel
Microsoft Excel
Microsoft Excel is a proprietary commercial spreadsheet application written and distributed by Microsoft for Microsoft Windows and Mac OS X. It features calculation, graphing tools, pivot tables, and a macro programming language called Visual Basic for Applications...

, etc.) includes (ordinarily invisible) identifying information in each formatted file it saves. The information might be name / organization / email address (collected at 'product registration' and retained internally), or product copy serial number, or computer ID (e.g., CPU serial number, or interface hardware address (e.g., Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

 MAC address
MAC address
A Media Access Control address is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet...

, a unique in the world ID), or ... One software program which claims to remove such information from files notes that there are about 30 different kinds in Word format files. Those interested in anonymity should limit themselves to plain text messages (ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...

 text only) produced by plain text editors (e.g., vi
Vi
vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.The original code for vi...

, emacs
Emacs
Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively...

, Notepad, ...) as they don't include such hidden information. Alternatively, users should take great care to inspect files (e.g., text, images, sound files, ...) to ensure they contain no identifying information. Note however, that even byte-by-byte inspection will not necessarily uncover such information since it can be easily concealed by encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...

, steganography
Steganography
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message, a form of security through obscurity...

, or simple unfamiliarity.

Anonymity, once lost, can almost never be regained as those interested in breaching it will often keep (and have often kept) records of such discoveries. Such records have typically had very long lives, particularly if those keeping them have long planning horizons (e.g., governments, or groups with social or political interests). For some opinions or speech, this may have, or come to have, serious consequences.
Not all anonymous remailers are identical, even when all work as intended. Close attention to operational standards and intent, locations, and reliability records is needed before choosing one. Among the criteria which should be considered are:
  • Class: (two-way or one-way, encrypted message content or cleartext only, mixmaster style or one hop forwarding, ...)
  • Location: Some offshore jurisdictions permit seizure of equipment, data, or operating records) Geographical Mapping
  • History: Operators who maintain and administer hardware and software in better condition than others; paying particular attention to security configuration issues)
  • Security: Some operating system
    Operating system
    An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

    s have worse security histories than others, even when properly configured, maintained, and administered)
  • Operator: At worst, a remailer run by some infamous Secret Police Department. an operator may be ominously inattentive)
  • Privacy and operating policies: If stated, better than not stated. If stated, sensible, and observed, better still. However, recourse (legal or otherwise) has almost never been available against operators, software developers, operating system suppliers, especially in cases of loss of anonymity and/or consequent damages, regardless of operating policies)
  • Software: Some remailer software is widely used (and live tested), some is not.
  • Record and reputation: Consult remailer statistics sites, and check (Google
    Google
    Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

     search, news group postings, blog
    Blog
    A blog is a type of website or part of a website supposed to be updated with new content from time to time. Blogs are usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in...

    s, ...


There is no way to ensure that a particular remailer server will never cause problems for its users (loss of identity or confidentiality). A remailer system not under one's own (expert level) control will always remain unknown.

Remailer statistics

In most cases, remailers are owned and operated by individuals, and are not as stable as they might ideally be. In fact, remailers can, and have, gone down without warning. It is important to use up-to-date statistics
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....

 when choosing remailers.

Remailer software

  • QuickSilver and QuickSilver Lite remailer software are Windows e-mail
    E-mail
    Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...

     client applications which send messages through Mixmaster anonymous remailer
    Mixmaster anonymous remailer
    Mixmaster is a Type II anonymous remailer which sends messages in fixed-size packets and reorders them, preventing anyone watching the messages go in and out of remailers from tracing them. Mixmaster was originally written by Lance Cottrell, and was maintained by Len Sassaman Peter Palfrader is the...

     cascades. The newer Lite version is capable of SSL/TLS
    Transport Layer Security
    Transport Layer Security and its predecessor, Secure Sockets Layer , are cryptographic protocols that provide communication security over the Internet...

     but lacks nym server
    Pseudonymous remailer
    A pseudonymous remailer or nym server, as opposed to an anonymous remailer, is an Internet software program designed to allow people to write pseudonymous messages on Usenet newsgroups and send pseudonymous email. Unlike purely anonymous remailers, it assigns its users a user name, and it keeps a...

     support.
  • OmniMix is a Windows proxy server, which handles e-mail
    E-mail
    Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...

     and usenet
    Usenet
    Usenet is a worldwide distributed Internet discussion system. It developed from the general purpose UUCP architecture of the same name.Duke University graduate students Tom Truscott and Jim Ellis conceived the idea in 1979 and it was established in 1980...

     postings that come from an ordinary client application in a transparent manner and sends them optionally through the Mixmaster anonymous remailer
    Mixmaster anonymous remailer
    Mixmaster is a Type II anonymous remailer which sends messages in fixed-size packets and reorders them, preventing anyone watching the messages go in and out of remailers from tracing them. Mixmaster was originally written by Lance Cottrell, and was maintained by Len Sassaman Peter Palfrader is the...

     network dependent on its settings or certain header
    Header (information technology)
    In information technology, header refers to supplemental data placed at the beginning of a block of data being stored or transmitted. In data transmission, the data following the header are sometimes called the payload or body....

     flags. It's able to interact with nym servers
    Pseudonymous remailer
    A pseudonymous remailer or nym server, as opposed to an anonymous remailer, is an Internet software program designed to allow people to write pseudonymous messages on Usenet newsgroups and send pseudonymous email. Unlike purely anonymous remailers, it assigns its users a user name, and it keeps a...

    , supports SSL/TLS
    Transport Layer Security
    Transport Layer Security and its predecessor, Secure Sockets Layer , are cryptographic protocols that provide communication security over the Internet...

     and Tor
    Tor (anonymity network)
    Tor is a system intended to enable online anonymity. Tor client software routes Internet traffic through a worldwide volunteer network of servers in order to conceal a user's location or usage from someone conducting network surveillance or traffic analysis...

     with all external communication (NNTP
    Network News Transfer Protocol
    The Network News Transfer Protocol is an Internet application protocol used for transporting Usenet news articles between news servers and for reading and posting articles by end user client applications...

    /SMTP
    Simple Mail Transfer Protocol
    Simple Mail Transfer Protocol is an Internet standard for electronic mail transmission across Internet Protocol networks. SMTP was first defined by RFC 821 , and last updated by RFC 5321 which includes the extended SMTP additions, and is the protocol in widespread use today...

    /POP3
    Post Office Protocol
    In computing, the Post Office Protocol is an application-layer Internet standard protocol used by local e-mail clients to retrieve e-mail from a remote server over a TCP/IP connection. POP and IMAP are the two most prevalent Internet standard protocols for e-mail retrieval. Virtually all modern...

    ), offers a Tor controller and allows header filtering and an automated addition of hashcash
    Hashcash
    Hashcash is a proof-of-work system designed to limit email spam and denial-of-service attacks. It was proposed in March 1997 by Adam Back.-How it works:...

     tokens. The OpenPGP
    Pretty Good Privacy
    Pretty Good Privacy is a data encryption and decryption computer program that provides cryptographic privacy and authentication for data communication. PGP is often used for signing, encrypting and decrypting texts, E-mails, files, directories and whole disk partitions to increase the security...

     compliant 'Whole Message Encryption', which, by including the header section, even makes the structure of a message unrecognizable, can automatically secure non-anonymous communication as well.
  • News2Remail is an NNTP to remailer proxy for Windows.

See also

  • Anonymity
    Anonymity
    Anonymity is derived from the Greek word ἀνωνυμία, anonymia, meaning "without a name" or "namelessness". In colloquial use, anonymity typically refers to the state of an individual's personal identity, or personally identifiable information, being publicly unknown.There are many reasons why a...

  • Anonymous P2P
    Anonymous P2P
    An anonymous P2P communication system is a peer-to-peer distributed application in which the nodes or participants are anonymous or pseudonymous...

  • Data privacy
    Data privacy
    Information privacy, or data privacy is the relationship between collection and dissemination of data, technology, the public expectation of privacy, and the legal and political issues surrounding them....

  • Identity theft
    Identity theft
    Identity theft is a form of stealing another person's identity in which someone pretends to be someone else by assuming that person's identity, typically in order to access resources or obtain credit and other benefits in that person's name...

  • Mixminion
    Mixminion
    Mixminion is the standard implementation of the Type III anonymous remailer protocol. Mixminion can send and receive anonymous e-mail.Mixminion uses a mix network architecture to provide strong anonymity, and prevent eavesdroppers and other attackers from linking senders and recipients...

  • I2P-Bote
  • Onion routing
    Onion routing
    Onion routing is a technique for anonymous communication over a computer network. Messages are repeatedly encrypted and then sent through several network nodes called onion routers. Like someone unpeeling an onion, each onion router removes a layer of encryption to uncover routing instructions, and...

  • Penet remailer
    Penet remailer
    The Penet remailer was a pseudonymous remailer operated by Johan "Julf" Helsingius of Finland from 1993 to 1996. Its initial creation stemmed from an argument in a Finnish newsgroup over whether people should be required to tie their real name to their online communications...

  • Privacy-enhancing technologies
  • Pseudonymous remailer
    Pseudonymous remailer
    A pseudonymous remailer or nym server, as opposed to an anonymous remailer, is an Internet software program designed to allow people to write pseudonymous messages on Usenet newsgroups and send pseudonymous email. Unlike purely anonymous remailers, it assigns its users a user name, and it keeps a...

  • Sharpmail
  • Traffic analysis
    Traffic analysis
    Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication. It can be performed even when the messages are encrypted and cannot be decrypted. In general, the greater the number of messages observed, or even intercepted and...

  • Winston Smith Project
    Winston Smith Project
    The Winston Smith Project is an informational and operational project for the defence of human rights on the Internet and in the digital era. It was started in 1999 as an anonymous association and it is characterised by the absence of a physical reference identity.It is named after the main...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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