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

March, 2007
Contingency planning includes a full range of integrated logistics support functions. Spare parts
(including copies of critical software programs, manuals, and data files) should be available
(acquired or arranged for) and pre-positioned (or delivery staged). Emergency maintenance,
replacement, and/or bypass instructions should be prepared and disseminated to both designated
individuals and to an accessible and advertised access point. Designated individuals should be
trained in their assigned recovery procedures, and all personnel should be trained in reporting
procedures and workstation-specific recovery procedures.
9.3.3.2 Cryptography and Key Management-specific Recovery Issues
Cryptographic keys are relatively small components or data elements that often control access to
large volumes of information or critical processes. As the Office of Management and Budget has
noted [OMB11/01], “without access to the cryptographic key(s) needed to decrypt information
[an] agency risks losing access to its valuable information.” Agencies are reminded of the need
to protect the continuity of their information technology operations and agency services when
implementing encryption. The guidance particularly stresses that agencies must address
information availability and assurance requirements through appropriate data recovery
mechanisms, such as cryptographic key recovery.
Key recovery generally involves some redundancy, or multiple copies of keying material. If one
copy of a critical key is lost or corrupted, another copy usually needs to be available in order to
recover data and/or restore capabilities. At the same time, the more copies of a key that exist and
are distributed to different locations, the more susceptible the key usually is to compromise
through penetration of the storage location or subversion of the custodian (e.g., user, service
agent, key production/distribution facility). In this sense, key confidentiality requirements
conflict with continuity of operations requirements. Special care needs to be taken to safeguard
all copies of keying material, especially symmetric keys and private asymmetric keys. More
detail regarding contingency plans and planning requirements is provided in Part 2 of this
Recommendation for Key Management.
9.3.4 Compromise Recovery
When keying material that is used to protect sensitive information or critical processes is
disclosed to unauthorized entities, all of the information and/or processes protected by that
keying material becomes immediately subject to disclosure, modification, subversion, and/or
denial of service. All compromised keys shall be revoked; all affected keys shall be replaced;
and, where sensitive or critical information or processes are affected, an immediate damage
assessment should be conducted. Measures necessary to mitigate the consequences of suspected
unauthorized access to protected data or processes and to reduce the probability or frequency of
future compromises may follow.
Where symmetric keys or private asymmetric keys are used to protect only a single user’s local
information or communications between a single pair of users, the compromise recovery process
can be relatively simple and inexpensive. Damage assessment and mitigation measures are often
local matters.
On the other hand, where a key is shared by or affects a large number of users, damage can be
widespread, and recovery is both complex and expensive. Some examples of keys, the
compromise of which might be particularly difficult or expensive to recover from, include the
following:
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