Cryptography Reference
In-Depth Information
Athirdkey,the
content-hash key
, is created by hashing the entire
document. The author can decide which keys to include with the
document when publishing it.
Obviously maintaining some central index of keys, documents
and the servers holding them would make life easier for everyone
including those who seek to censor the system. Freenet avoids this
process, but does take one step to make the searching process eas-
ier. When new documents are inserted into the network, the author
places them on servers which hold similar keys. The storing proce-
dure searches the network looking at similar keys and then places the
document there.
10.4.5 OceanStore
One of themore ambitious projects for persistent, robust, distributed
storage is OceanStore developed by a large group of faculty and stu-
dents at the University of California at Berkeley. Many of the basic
ideas and the flavor of the project are clearly inspired by the Freenet
project, but embellishedwithmore sophisticated tools for upgrading
and duplicating documents. [KBC
+
00]
The most significant addition is a mechanism for ensuring that
documents aren't destroyed when they are updated. Blocks of new
data can be inserted into documents and these changes propagate
through the network until all copies are current. The mechanism
also contains a more sophisticated routing structure to speed the
identification and location of documents. All of these details are
beyond the current scope of the topic.
10.5 Long term storage
Anonymous remailers normally do their work in a few split seconds,
deliver their message to the right person, and then move on. What if
we want a send a message that lasts? What if we want to post a mes-
sage where it will be available for a long time? You could always buy
a server, pay for a connection and keep paying the bills but that may
not work. Controversial material can be shut down with many differ-
ent types of legal challenges and most server farms aren't willing to
spend too much time or energy against determined opponents.
This technique is becoming increasingly controversial because
the algorithms are used to store and exchange copyrighted music
and video files.
