Part 1: General - Computer Security Resource Center - National ...

March, 2007
8.1.5.3.5 Intermediate Results
Intermediate results occur during computation using cryptographic algorithms. These results
shall not be distributed.
8.1.6 Key Registration Function
Key registration results in the binding of keying material to information or attributes associated
with a particular entity. This information typically includes the identifier of the entity associated
with the keying material and the intended use of the keying material (e.g., signing key, data
encryption key, etc.). Additional information may include authorization information or specify
the level of trust. The binding is performed after the entity’s identity has been authenticated by a
means that is consistent with the system policy. Human entities are usually required to provide
credentials (e.g., identification card or birth certificate), while system entities are vouched for by
those responsible for their operation. The binding provides assurance to the community at large
that the keying material is used by the correct entity in the correct application. The binding is
often cryptographic, which creates a strong association between the keying material and the
entity. A trusted third party performs the binding. Examples of a trusted third party include a
Kerberos realm server or a PKI certification authority (CA). Identifiers issued by a trusted third
party shall be unique to that party.
When a Kerberos realm server performs the binding, a symmetric key is stored on the server
with the corresponding attributes, In this case, the registered keying material is maintained in
confidential storage (i.e., the keys are provided with confidentiality protection).
When a CA performs the binding, the public key and associated attributes are placed in a public
key certificate, which is digitally signed by the CA. In this case, the registered key material may
be publicly available.
When a CA provides a certificate for a public key, the public key shall be verified to ensure that
it is associated with the private key known by the purported owner of the public key. This
provides assurance of possession. When POP is used to obtain assurance of possession, the
assurance shall be accomplished using the keys for their intended function. For example, the
assurance of possession of a private key transport key is provided using a key transport function,
not a digital signature function.
8.2 Operational Phase
Keying material used during the cryptoperiod of a key is often stored for access as needed.
During storage, the keying material shall be protected as specified in Section 6.2.2. During
normal use, the keying material is stored either on the device or module that uses that material,
or on a readily accessible storage media. When the keying material is required for operational
use, the keying material is acquired from immediately accessible storage when not present in
active memory within the device or module.
To provide continuity of operations when the keying material becomes unavailable for use from
normal operational storage during its cryptoperiod (e.g., because the material is lost or
corrupted), keying material may need to be recoverable. If an analysis of system operations
indicates that the keying material needs to be recoverable, then the keying material shall either
be backed up (see Section 8.2.2.1), or the system shall be designed to allow reconstruction (e.g.,
102