Key management objectives, threats, and policy

Key management plays a fundamental role in cryptography as the basis for securing cryptographic techniques providing confidentiality, entity authentication, data origin authentication, data integrity, and digital signatures. The goal of a good cryptographic design is to reduce more complex problems to the proper management and safe-keeping of a small number of cryptographic keys, ultimately secured through trust in hardware or software by physical isolation or procedural controls. Reliance on physical and procedural security (e.g., secured rooms with isolated equipment), tamper-resistant hardware, and trust in a large number of individuals is minimized by concentrating trust in a small number of easily monitored, controlled, and trustworthy elements.

Keying relationships in a communications environment involve at least two parties (a sender and a receiver) in real-time. In a storage environment, there may be only a single part)', which stores and retrieves data at distinct points in time.

The objective of key management is to maintain keying relationships and keying material in a manner which counters relevant threats, such as;

  • 1. compromise of confidentiality of secret keys.
  • 2. compromise of authenticity of secret or public keys. Authenticity requirements include knowledge or verifiability of the true identity of the party a key is shared or associated with.
  • 3. unauthorized use of secret or public keys. Examples include using a key which is no longer valid, or for other than an intended purpose (see Remark 13.32).

In practice, an additional objective is conformance to a relevant security policy.

Security policy and key management

Key management is usually provided within the context of a specific security’ policy. A security policy explicitly or implicitly defines the threats a system is intended to address. The policy may affect the stringency of cryptographic requirements, depending on the susceptibility of the environment in question to various types of attack. Security policies typically also specify:

  • 1. practices and procedures to be followed in carrying out technical and administrative aspects of key management, both automated and manual;
  • 2. the responsibilities and accountability of each party involved; and
  • 3. the types of records (audit trail information) to be kept, to support subsequent reports or reviews of security-related events.
 
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