XID

XID, short for Transaction ID, is a unique identifier associated with a specific transaction in the authentication process. In the context of online credit and debit card transactions, 3DS adds an additional layer of security by authenticating the .

The XID serves as a reference key that links the 3DS transaction to the authentication details exchanged between the cardholder's , the merchant, and the . It plays a crucial role in tracking and reconciling 3DS transactions, providing a means to associate authentication responses with the corresponding payment transactions. The XID is utilized in the 3DS protocol to enhance the security of online transactions, reduce the risk of unauthorized card use, and provide a standardized method for authentication across different payment platforms and card networks.