Editing Tokenization (data security) (section)

== Types of tokens ==
There are many ways that tokens can be classified however there is currently no unified classification. Tokens can be: single or multi-use, [[Cryptography|cryptographic]] or non-cryptographic, reversible or irreversible, authenticable or non-authenticable, and various combinations thereof.

In the context of payments, the difference between high and low value tokens plays a significant role.

=== High-value tokens (HVTs) ===
HVTs serve as surrogates for actual [[Payment card number|PANs]] in payment transactions and are used as an instrument for completing a payment transaction. In order to function, they must look like actual PANs. Multiple HVTs can map back to a single PAN and a single physical credit card without the owner being aware of it. Additionally, HVTs can be limited to certain networks and/or merchants whereas PANs cannot.

HVTs can also be bound to specific devices so that anomalies between token use, physical devices, and geographic locations can be flagged as potentially fraudulent. HVT blocking enhances efficiency by reducing computational costs while maintaining accuracy and reducing record linkage as it reduces the number of records that are compared.<ref>O’hare, K., Jurek-Loughrey, A., & De Campos, C. (2022). High-Value Token-Blocking: Efficient Blocking Method for Record Linkage. ACM Transactions on Knowledge Discovery from Data, 16(2), 1–17. https://doi.org/10.1145/3450527</ref>

=== Low-value tokens (LVTs) or security tokens ===
LVTs also act as surrogates for actual PANs in payment transactions, however they serve a different purpose. LVTs cannot be used by themselves to complete a payment transaction. In order for an LVT to function, it must be possible to match it back to the actual PAN it represents, albeit only in a tightly controlled fashion. Using tokens to protect PANs becomes ineffectual if a tokenization system is breached, therefore securing the tokenization system itself is extremely important.