Transaction Data Signing (TDS) is the generation of a code, used as part of the authentication and transaction verification
process that is cryptographically generated from the actual underlying transaction content. This differs from a One-Time-Passcode (OTP),
such as those generated by hardware tokens, which have no relationship to the underlying data.

TDS codes form part of an overall non-repudiation solution and are used, in conjunction with the TDS algorithm,
to re-create the transaction in non-repudiation disputes. To facilitate non-repudiation TDS codes are generally stored
in tamper-evident audit logs within the Bank or by a trusted third-party. VALid allows significant flexibility and extensibility
for the process of generating TDS codes, including different inputs, different MAC algorithms and different offline storage options.

For further information, please download the white paper labelled "Transactional Non-repudiation: A new fraud landscape necessitates a new approach".