seems to be a BCC mechanism (20010055396)

[John Kane]

Picture this:
 I write a program which takes a multiple-recipient OpenPGP
 file and 'splits' it into separate files, each encrypted-to only
 one recipient. (The sym-encrypted message body section
 will of course be identical across all the split files.)  My
 program then emails each single-encrypted file to its
 intended recipient.
That seems to be what he has in mind.

 From what I can tell, the 'novel' element seems to be that
he proposes automatic stripping of all the public-key headers
except the one addressed to the recipient, so that none of
the recipients knows who else got a copy; this is equivalent
to a Blind-Carbon-Copy system applied to multiple-recipient
encrypted messages.

NOTE: the anon/relay cipherpunk remailers already implement
a similar BCC option in their protocol; this might prove to
be prior art.

The other novel element might be the implied separation
between the symmetrically-encrypted message body part
and the list of public-key routing/decryption headers.
(Whereas PGP glues both of those together in one file.)

--
John Kane
Stratham, NH (USA)