Code identifying the security algorithms and methods employed for this level of interchange.

If S2S01 is ``AA'' or ``BB'', S2S04 is required.

If S2S01 is ``BB'' or ``EE'', S2S06 is required.

Unique designation (identity) of the cryptographic entity that performs authentication or encryption on data to be interchanged, or originates a cryptographic service message. No mechanism, or registration method is provided by X9 or X12 to guarantee uniqueness of the identifier.

Unique designation (identity) of the cryptographic entity that performs authentication or decryption on received data or is the destination of a cryptographic service message. No mechanism, or registration method, is provided by X9 or X12 to guarantee the uniqueness of the identifier.

Name of the key used for authentication. This name is mutually known to the security originator and the security recipient, is unique for this relationship, and allows a particular key to be specified.

Authentication option

Name of the key used for encryption. This name is mutually known to the security originator and the security recipient, is unique for this relationship, and allows a particular key to be specified.

Coded values representing options for encryption processing. The code defines the encryption mode and the transmission filter specification for filtering binary ciphertext data into transmittable text.

Length of data is the number of character positions of the encrypted, filtered text.

The archival representation of a 64-bit value expressed in hexadecimal notation as 16 ASCII characters from the set of characters (0..9, A..F). The 64-bit value is used as a starting point for encryption of a data sequence to increase security by introducing cryptographic variance and to synchronize cryptographic equipment. A new IV shall be used for each message. The IV shall not be intentionally reused. The 64-bit binary value, not its ASCII hexadecimal representation, is used for the cryptographic process. In the interchange process, the resultant encrypted and filtered 64-bit IV is sent. The hexadecimal notation is the representation for archiving purposes. The IV shall be a random or pseudo-random number. When encrypted, the IV shall be decrypted using the Electronic Code Book (ECB) mode, and the same key that was used to encrypt the message.