comStar Firewall alert - PhaseThrough

systeM security . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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optionaL rULe: draMatic encrYption
As a gamemaster, you may wish to use an encrypted
file or node as a story hook or a plot device.
With the state of cryptography what it is in the 2070s,
encryption presents a very low bar for players.
Fortunately, there exist unique and particularly
arcane encryption methods that represent either
bleeding-edge research or ancient techniques that
cannot be easily cracked by computers. These methods
can only be decrypted under special circumstances,
such as only in a certain place, using information from
a particular object, only after finding all parts of a file,
or simply after an inordinate amount of time. The
details of such methods, including availability and
frequency, are determined by the gamemaster.
side of the link must be running Encrypt. There is no advantage if
both connected nodes are running Encrypt, except that the highest
rating of the two programs is used. Initiating signals encryption
requires a Simple Action by each node, but no further action is
needed to encrypt or decrypt data sent along the link until the
encryption is disabled or the link is severed. Encrypted connections
take up a subscription slot (see Subscriptions, p. 55).
file encryption
Files can be encrypted with a Simple Action, using the
Encrypt program. When encrypting a file, a user may include more
than one file, to create a single encrypted archive file containing
several smaller files.
A user may also include a Data Bomb program within the
archive file. When doing so, the user also determines the conditions
by which the Data Bomb will not activate (usually when
it is decrypted using the key rather than by use of Decrypt) and
whether or not the Data Bomb will destroy some, all, or none of
the files within the encrypted archive. An encrypted archive may
contain only one Data Bomb. See Data Bomb, p. 226, SR4.
Additionally, a user may include an IC program (which may
in turn be loaded with other programs) in an encrypted archive
file. During this process, the user configures the IC’s behavior
when the archive is decrypted, usually including a clause that keeps
the IC from activating if the proper key is used. Barring instructions
to the contrary, the included IC automatically loads into the
node in which the archive file is decrypted. Only one IC program
may be included in an archive file.
The presence of a Data Bomb or IC can be detected with a
successful Matrix Perception Test performed on the archive file.
node encryption
An entire node can be encrypted as an extra layer of security.
An encrypted node can normally only be accessed by a user that has
the correct key. A hacker may Decrypt the node, after which she can
access it, as can anyone else with whom she shares the Decrypted key.
The node must have an Encrypt program running, which counts
against its program count for Response reduction. Encrypting a
node does not automatically also encrypt subscriptions to or from
it or files within it. Encrypting a node requires a Simple Action.
Strong encryption
While cryptanalysis is far stronger than encryption these
days, it is possible to slow down an attacker more than standard
encryption can. Doing so takes a large amount of processing
power and time, and is considered by some hackers to be not
worth the extra effort.
When using strong encryption, the user needs the Encrypt
program, as with normal encryption. The amount of time taken
to perform the strong encryption then becomes the interval
for an attacker’s Decryption Extended Test (p. 225, SR4). The
longest period to which the interval may be increased is one
day; beyond twenty-four hours, the encryption suffers from
dramatic diminishing returns.
Strong encryption may not be used for signals encryption.
dynamic encryption
It is possible to perform continuous re-encryption by
monitoring a decryption attempt and adjusting the encryption
algorithm accordingly. Doing so does not make the encryption
safe, but it can delay an attacking hacker. Like strong encryption,
dynamic encryption takes extra time and processing power. It
has the additional disadvantage that it requires awareness of an
attacker for it to be effective.
Dynamic encryption is only effective against an attacker that
has been detected with a Matrix Perception Test and that is currently
decrypting a link, file, or node. The user makes an Opposed
Computer + Encrypt Test against the attacker’s Electronic Warfare
+ Decrypt; for every net hit on this test, the threshold for the attacker’s
attempt to break the encryption is increased by one. This
requires a Complex Action.
The extra threshold applies only to the attacker against which
it is directed. The attacker may clear the threshold penalty by restarting
his decryption attempt, but this causes him to lose any hits
already accumulated against the encryption.
Once an attacker has fully decrypted a subscription, node, or
file, this technique may no longer be used. Dynamic encryption is
not compatible with strong encryption.
decryption
Most of the time, encrypted subscriptions, files, and nodes
are decrypted with a key. Often they are decrypted by hackers
who crack the encryption with the Decrypt program. Using the
Decrypt program requires a Complex Action to start the process,
but thereafter the program continues the Extended Test (p. 225,
SR4) autonomously. Once a file is decrypted by any user, it remains
decrypted, but when a subscription or node is decrypted by a user,
it remains decrypted only for that user. However, the encryption
may be re-instated under certain circumstances:
Signals encryption may be restored by closing the subscription
(a Log Off action), re-establishing the subscription (a Log On
action), and then re-encrypting the subscription (a Simple Action
from each side of the link).
File encryption is restored merely by encrypting the nowdecrypted
file.
Node encryption is restored by rebooting the node (a
Complex Action, plus boot time), and re-encrypting it (a Simple
Action).
Unwired
Simon Wentworth (order #1132857) 9