C1. All IVPs must ensure that all CDIs are in a valid
state when the IVP is run.
C2. All TPs must be certified to be valid, and each TP is
assocated with a set of CDIs it is authorized to
E1. The system must maintain these lists and must ensure
only those TPs manipulate those CDIs.
E2. The system must maintain a list of User IDs, TP, and
CDIs that that TP can manipulate on behalf of that user, and must
ensure only those executions are performed.
C3. The list of relations in E2 must be certified to meet
the separation of duty requirement.
E3. The sysem must authenticate the identity of each user
attempting to execute a TP.
C4. All TPs must be certified to write to an append-only
CDI (the log) all information necessary to resonstruct the
C5. Any TP taking a UDI as an input must be certified to
perform only valid transformations, else no transformations, for
any possible value of the UDI. The transformation should take the
input from a UDI to a CDI, or the UDI is rejected (typically, for
edits as the keyboard is a UDI).
E4. Only the agent permitted to certify entities may
change the list of such entities associated with a TP. An agent
that can certify an entity may not have any execute rights with
respect to that entity.
Codes vs. ciphers
Attacks: ciphertext only, known plaintext, chosen
Types: substitution, transposition
Monoalphabetic (simple substitution):
a + k
Example: Caesar with k = 3,
RENAISSANCE → UHQDLVVDQFH