Cyphernomicon Top
Cyphernomicon 8.5

Anonymity, Digital Mixes, and Remailers:
Untraceable E-Mail


    8.5.1. The Basic Idea of Remailers
           - Messages are encrypted, envelopes within envelopes, thus
              making tracing based on external appearance impossible. If
              the remailer nodes keep the mapping between inputs and
              outputs secret, the "trail" is lost.
    8.5.2. Why is untraceable mail so important?
           + Bear in mind that "untraceable mail" is the default
              situation for ordinary mail, where one seals an envelope,
              applies a stamp, and drops it anonymously in a letterbox.
              No records are kept, no return address is required (or
              confirmed), etc.
             - regional postmark shows general area, but not source
                mailbox
             + Many of us believe that the current system of anonymous
                mail would not be "allowed" if introduced today for the
                first time
               - Postal Service would demand personalized stamps,
                  verifiable return addresses, etc. (not foolproof, or
                  secure, but...)
           + Reasons:
             - to prevent dossiers of who is contacting whom from being
                compiled
             - to make contacts a personal matter
             - many actual uses: maintaining pseudonyms, anonymous
                contracts, protecting business dealings, etc.
    8.5.3. How do Cypherpunks remailers work?
    8.5.4. How, in simple terms, can I send anonymous mail?
    8.5.5. Chaum's Digital Mixes
           - How do digital mixes work?
    8.5.6. "Are today's remailers secure against traffic analysis?"
           - Mostly not. Many key digital mix features are missing, and
              the gaps can be exploited.
           + Depends on features used:
             - Reordering (e.g., 10 messages in, 10 messages out)
             - Quantization to fixed sizes (else different sizes give
                clues)
             - Encryption at all stages (up to the customer, of course)
           - But probably not, given that current remailers often lack
              necessary features to deter traffic analysis. Padding is
              iffy, batching is often not done at all (people cherish
              speed, and often downcheck remailers that are "too slow")
           - Best to view today's remailers as experiments, as
              prototypes.
  

Next Page: 8.6 Remailers and Digital Mixes (A Large Section!)
Previous Page: 8.4 Reasons for Anonymity and Digital Pseudonyms (and Untraceable E-

By Tim May, see README

HTML by Jonathan Rochkind