4.2.5.3 Security Properties of the Key-Establishment Schemes
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Title
Security Properties of the Key-Establishment Schemes
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Cryptographic protocol designers need to understand the security properties of the schemes in order to assure that the desired capabilities are available to the user. In general, schemes where each party uses both an ephemeral and a static key provide more security properties than schemes using fewer keys. However, it may not be practical for both parties to use both static and ephemeral keys in certain applications. For example, in email applications, it is desirable to send messages to other parties who are not on-line; in this case, the receiver cannot be expected to provide an ephemeral key to establish the message-encrypting key during a [SP800-56A] key-agreement scheme. For the schemes in [SP800-56B] , ephemeral keys are never used. Both [SP80056A] and [SP800-56B] include discussions of the security properties of each of its schemes.