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8.2.4 Key Derivation Methods

NIST platform security: roots of trust, firmware and secure enclaves SP 800-57 Part 1 Rev. 5 against SP 800-57 Part 1 Rev. 4
All changes in this version
modified 8 Transition: A transition plan should be developed and followed so that the changeover part of 8.2

Title

Key Derivation Methods

Control changed

Before · SP 800-57 Part 1 Rev. 4

Cryptographic keys may be derived from a secret value. The secret value, together with other information, is input into a key-derivation method (e.g., a key-derivation function) that outputs the required key(s). In contrast to key change (as discussed in Section 8.2.3 ), the derived keys are often used for new purposes, rather than for replacing the secret values from which they are derived. The derivation method shall be non-reversible (i.e., a one-way function) so that the secret value cannot be determined from the derived keys. In addition, it shall not be possible to determine a derived key from other derived keys. It should be noted that the strength of a derived key is no greater than the strength of the derivation algorithm and the secret value from which the key is derived. Three commonly used key-derivation cases are discussed below.

After · SP 800-57 Part 1 Rev. 5

Cryptographic keys may be derived from a secret value. The secret value, together with other information, is input into a key-derivation method (e.g., a key-derivation function) that outputs the required key(s). In contrast to key change (as discussed in Section 8.2.3 ), the derived keys are often used for new purposes, rather than for replacing the secret values from which they are derived. The derivation method shall be non-reversiblenonreversible (i.e., a one-way function) so that the secret value cannot be determined from the derived keys. In addition, it shall not be possible to determine a derived key from other derived keys. It should be noted that the strength of a derived key is no greater than the strength of the derivation algorithm and the secret value from which the key is derived. Three commonly used key-derivation cases are discussed below. 1. Two parties derive common keys from a common shared secret. This approach is used in the key-agreement techniques specified in SP 800-56A and SP 800-56B . The security of this process is dependent on the security of the shared secret and the specific key-derivation method used. If the shared secret is known, the derived keys can be determined. A key- derivation method specified or allowed in SP 800-56C 101 shall be used for this purpose. These derived keys may be used to provide the same confidentiality, identity authentication, and source authentication services as randomly generated keys. The security strength of the derived keys is determined by the scheme and key pairs used to generate the shared secret.