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

7 Key States and Transitions
A key may pass through several states between its generation and its destruction.
March, 2007
7.1 Key States
A key is used differently depending upon its state in the life cycle. Key states are defined from a
system point of view, as opposed to a single cryptomodule point of view.
1. Pre-activation state: The key has been generated, but is not yet authorized for use. In
this state the key may only be used to perform proof of possession or key confirmation
(see Section 8.1.5.1.1.2 and Section 4.2.5.5). Other than for proof of possession (Section
8.1.5.1.1.2) or key confirmation (Section 4.2.5.5) purposes, a key is not used to apply
cryptographic protection to information (e.g., encrypt or sign information to be
transmitted or stored) while in this state. Other than for proof of possession or key
confirmation purposes, the key is not used to process cryptographically protected
information (e.g., decrypt ciphertext or verify a digital signature) while in this state.
2. Active state: The key may be used to cryptographically protect information or to
cryptographically process previously protected information (e.g., decrypt ciphertext or
verify a digital signature) or both. When a key is active, it may be designated to protect
only, process only, or both protect and process. Private signature generation keys are
implicitly designated as protect only; public signature verification keys are designated as
process only. A symmetric data encryption key may be used for a predetermined period
of time to both encrypt and decrypt information. When that period expires, the key may
transition to process only (See Section 5.3.4.2) within the active state.
3. Deactivated state: A key whose cryptoperiod has expired but is still needed to perform
cryptographic processing is deactivated until it is destroyed. A deactivated key is not used
to apply cryptographic protection to information, but in some cases it may be used to
process cryptographically protected information. When a key in the deactivated state is
no longer required for processing cryptographically protected information, the key is
destroyed (see Section 8.3.4).
4. Destroyed state: The key is destroyed as specified in Section 8.3.4. Even though the key
no longer exists in this state, certain key attributes (e.g., key name, type, and
cryptoperiod) may be retained (see Section 8.4).
5. Compromised state: Generally, keys are compromised when they are released to or
determined by an unauthorized entity. If the integrity or secrecy of the key is suspect, the
compromised key is revoked (see Section 9.3.4). This state may be entered from all states
except the destroyed and destroyed compromised states. A compromised key is not used
to apply cryptographic protection to information. In some cases, a compromised key may
be used to process cryptographically protected information, even though the
confidentiality, integrity, non-repudiation or associations of the information may be
suspect. For example, a signature may be validated if it can be shown that the signed data
with its signature has been physically protected since a time before the compromise
occurred. This processing is done only under very highly controlled conditions where the
users of the information are fully aware of the possible consequences.
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