Remailer messages of variable length

Anonymous nobody at hidden.net
Mon May 19 20:21:57 PDT 1997


To complicate traffic analysis Sender can add a padding to his message
before encrypting it for some remailer in chain. So that the
message is shortened after decryption and stripping of pseudo headers.
It can be done with a dummy header lines:

##
Padding: fjx6zRURnnK1DV4CdL7gbHpnUiV1KbbRf5HatXiaD+ZPtH0 ...

Also, for a length increment a remailer may understand commands like:

##
Pad-length: 1K
Pad-encrypt-for: remailer at replay.com

It will then add the 'Padding:' header and re-encrypt the message with
the appropriate remailer's public key. The next remailer in chain will see
the padding and will try do decrypt the message twice...

If stealth crypto is used, a random padding can be simply attached to the
end of the message.

Also, the remailer by itself can decide to increase a message length to
cover some rare big messages.

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