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(mailcrypt.info)Remailer Introduction

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Remailer Introduction
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   There are several anonymous remailer services running on the
Internet.  These are programs that accept mail, strip off information
that would identify the origin of the message, and forward the mail to
the designated recipient.  This simple scheme alone, however, is
insecure if the anonymous remailer becomes compromised (or if the
remailer was set up by an untrustworthy party in the first place).
Whoever controls the remailer will have access to the identities of
senders and recipients.

   One solution to this is to use _chains_ of remailers that send
encrypted messages.  For example, suppose Bill wishes to send a message
to Louis using a chain of remailers A, B, and C.  He writes the message
(possibly encrypting it for Louis), then encrypts the result (including
the fact that Louis is the recipient) using a public key supplied by
remailer C.  Then he encrypts this result using a public key supplied by
remailer B.  Then he encrypts this result using a public key supplied by
A and sends the message to A.

   When A receives the message, it decrypts the message with its key to
produce something encrypted for B, learns that the next remailer in the
chain is B, strips off the information that the message came from Bill,
and sends the message on to B.  B then decrypts, learns that the next
remailer in the chain is C, strips off the information that the message
came from A, and sends the result to C.  C then decrypts, learns that
the destination is Louis, strips off the information that the message
came from B, and sends the result to Louis.  With this arrangement, only
A knows that the original message came from Bill, and only C knows that
the intended recipient is Louis.  In general, the sender and recipient
can both be known only to someone who has compromised all remailers in
the chain.

   If Bill wishes, he can include an encrypted "response block" in his
message to Louis, which defines a remailer chain that Louis can use to
reply to Bill.  Louis can use this chain without knowing who Bill is -
only the last remailer in the chain need know the final recipient.  Bill
can also establish a _pseudonym_ for use in signing his anonymous
messages.

   Mailcrypt includes facilities for sending messages via remailers, for
defining chains of remailers, for generating response blocks, and for
using pseudonyms.