Foreword

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This document was prepared by Technical Committee ISO/TC 68, Financial services, Subcommittee SC 2, Financial services, security.

This second edition cancels and replaces the first edition ( ISO 20038:2017 ), which has been technically revised.

The main changes are as follows:

updated for compatibility with ANSI X9.143-2022 .

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

The secure management of cryptographic keys requires that their values and usage constraints be protected for both confidentiality and integrity.

This document provides a method of wrapping cryptographic keys in order to provide confidentiality and integrity protection for the keys when being transmitted or stored. The mechanism is designed to use advanced encryption standard (AES) specified in FIPS 197 as the wrapping cipher.

1 Scope

This document defines a method for packaging cryptographic keys for transport. This method can also be used for the storage of keys under an advanced encryption standard (AES) key. The method uses the block cipher AES as the wrapping cipher algorithm.

Other methods for wrapping keys are outside the scope of this document but can use the authenticated encryption algorithms specified in ISO/IEC 19772 .

2 Normative references

3 Terms, definitions and abbreviated terms

3.1 Terms and definitions

3.2 Abbreviated terms

4 Notation

5 Key block elements

6 Key block format

6.1 General

6.2 Key block header (KBH)

6.3 Defined values for key block headers

6.4 Encoding

7 Key block binding and validation methods

7.1 General

7.2 Key block binding method using key derivation

8 Examples

8.1 AES key block example

8.2 AES key block with optional blocks

8.3 RSA key block example with CT optional block

8.4 ECC key block example with CT certificate chain optional block

8.5 CTR mode without padding

Bibliography