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

March, 2007
6 Protection Requirements for Cryptographic Information
This section gives guidance on the types of protection for keying material. Cryptographic keying
material is defined as the cryptographic key and associated information required to use the key.
The specific information varies depending on the type of key. The cryptographic keying material
must be protected in order for the security services to be “meaningful.” Much of the protection
needed may be provided by a FIPS140-2 validated cryptographic module; however, whenever
the keying material exists external to a FIPS140-2 cryptomodule, additional protection is
required. The type of protection needed depends on the type of key and the security service for
which the key is used.
6.1 Protection Requirements
Keying material should be (operationally) available as long as the associated cryptographic
service is required. Keys may be maintained within a cryptographic module while they are being
actively used, or they may be stored externally (provided proper protection is afforded) and
recalled as needed. Some keys may need to be archived if required beyond the key’s originator
usage period (see Section 5.3.5).
The following protections may be provided to the keying material.
Integrity protection (Also called assurance of integrity) shall be provided for all keying
material. Integrity protection always involves checking the source and format of received
keying material (see Section 5.4.1). Integrity protection can be provided by cryptographic
integrity mechanisms (e.g. cryptographic checksums, cryptographic hashes, MACs, and
signatures), non-cryptographic integrity mechanisms (e.g. CRCs, parity, etc.) (see
Appendix A), or physical protection mechanisms. Guidance for the selection of
appropriate integrity mechanisms is given in Sections 6.2.1.2 and 6.2.2.2.
The confidentiality of all symmetric and private keys shall be protected. Public keys
generally do not require confidentiality protection. When the symmetric or private key
exists internal to a validated cryptomodule, confidentiality protection is provided by the
cryptomodule in accordance with [FIPS140-2]. When the symmetric or private key exists
external to the cryptomodule, confidentiality protection shall be provided either by
encryption (e.g., key wrapping) or by controlling access to the key via physical means
(e.g. storing the keying material in a safe with limited access). The security and
operational impact of specific confidentiality mechanisms varies. Guidance for the
selection of appropriate confidentiality mechanisms is given in Sections 6.2.1.3 and
6.2.2.3.
Association protection shall be provided for a cryptographic security service by ensuring
that the correct keying material is used with the correct data in the correct application or
equipment. Guidance for the selection of appropriate association protection is given in
Sections 6.2.1.4 and 6.2.2.4.
Assurance of domain parameter and public key validity provides confidence that the
parameters and keys are arithmetically correct (see Section 5.4.2 and 5.4.3). Guidance for
the selection of appropriate validation mechanisms is given in [SP800-56], [FIPS186-3],
as well as this document.
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