Historical
ASC X9 TR 31-2018
Interoperable Secure Key Exchange Key Block Specification.
TR 31 describes a method consistent with the requirements of ANS X9.24 Retail Financial Services Symmetric Key Management Part 1 for the secure exchange of keys and other sensitive data between two devices that share a symmetric key exchange key. This method may also be used for the storage of keys under asymmetric key. This document is not a security standard and is not intended to establish security requirements. It is intended instead to provide an interoperable method of implementing security requirements and policies. This document is historical as X9.143-2021 Interoperable Secure Key Exchange Key Block Specification for Symmetric Algorithms is the newer version. Please refer to that version.
Accredited Standards Committee, Inc. - Financial Industry Standards [ascx9]