This International Standard describes a key management related data element that can be transmitted either in transaction messages to convey information about cryptographic keys used to secure the current transaction, or in cryptographic service messages to convey information about cryptographic keys to be used to secure future transactions. This International Standard addresses the requirements for the use of the key management related data element within ISO 8583, using the following two ISO 8583 data elements: — security related control information (data element 53), or — key management data (data element 96). However, these data elements can be usefully employed in other messaging formats, given that the transportation of key management related data is not limited to ISO 8583. This International Standard is applicable to either symmetric or asymmetric cipher systems. Key management procedures for the secure management of the cryptographic keys within the financial services environment are described in ISO 11568. Security related data, such as PIN data and MACs, are described in ISO 9564 and ISO 16609, respectively.