Updatable Tokenization: Formal Definitions and Provably Secure Constructions
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Tokenization is the process of consistently replacing sensitive elements, such as credit cards numbers, with non-sensitive surrogate values. As tokenization is mandated for any organization storing credit card data, many practical solutions have been introduced and are in commercial operation today. However, all existing solutions are static yet, i.e., they do not allow for efficient updates of the cryptographic keys while maintaining the consistency of the tokens. This lack of updatability is a burden for most practical deployments, as cryptographic keys must also be re-keyed periodically for ensuring continued security. This paper introduces a model for updatable tokenization with key evolution, in which a key exposure does not disclose relations among tokenized data in the past, and where the updates to the tokenized data set can be made by an untrusted entity and preserve the consistency of the data. We formally define the desired security properties guaranteeing unlinkability of tokens among different time epochs and one-wayness of the tokenization process. Moreover, we construct two highly efficient updatable tokenization schemes and prove them to achieve our security notions.
We would like to thank our colleagues Michael Osborne, Tamas Visegrady and Axel Tanner for helpful discussions on tokenization.
- 4.Boneh, D., Lewi, K., Montgomery, H.W., Raghunathan, A.: Key homomorphic PRFs and their applications. IACR Cryptology ePrint Archive 2015, 220 (2015). http://eprint.iacr.org/2015/220
- 5.Diaz-Santiago, S., Rodríguez-Henríquez, L.M., Chakraborty, D.: A cryptographic study of tokenization systems. In: Obaidat, M.S., Holzinger, A., Samarati, P. (eds.) Proceedings of the 11th International Conference on Security and Cryptography (SECRYPT 2014), Vienna, 28–30 August 2014, pp. 393–398. SciTePress (2014). https://doi.org/10.5220/0005062803930398
- 6.European Commission, Article 29 Data Protection Working Party: Opinion 05/2014 on anonymisation techniques (2014). http://ec.europa.eu/justice/data-protection/article-29/documentation/opinion-recommendation/
- 7.Everspaugh, A., Chatterjee, R., Scott, S., Juels, A., Ristenpart, T.: The Pythia PRF service. In: Jung, J., Holz, T. (eds.) 24th USENIX Security Symposium, USENIX Security 2015, Washington, D.C., 12–14 August 2015, pp. 547–562. USENIX Association (2015). https://www.usenix.org/conference/usenixsecurity15/technical-sessions/presentation/everspaugh
- 8.Herzberg, A., Jakobsson, M., Jarecki, S., Krawczyk, H., Yung, M.: Proactive public key and signature systems. In: Proceedings of the 4th ACM Conference on Computer and Communications Security (CCS 1997), Zurich, 1–4 April 1997, pp. 100–110 (1997). https://doi.org/10.1145/266420.266442
- 9.McCallister, E., Grance, T., Scarfone, K.: Guide to protecting the confidentiality of personally identifiable information (PII). NIST special publication 800-122, National Institute of Standards and Technology (NIST) (2010). http://csrc.nist.gov/publications/PubsSPs.html
- 10.PCI Security Standards Council: PCI Data Security Standard (PCI DSS) (2015). https://www.pcisecuritystandards.org/document_library?document=pci_dss
- 11.Securosis: Tokenization guidance: How to reduce PCI compliance costs. https://securosis.com/assets/library/reports/TokenGuidance-Securosis-Final.pdf
- 12.Smart Card Alliance: Technologies for payment fraud prevention: EMV, encryption and tokenization. http://www.smartcardalliance.org/downloads/EMV-Tokenization-Encryption-WP-FINAL.pdf
- 13.United States Department of Health and Human Services: Summary of the HIPAA Privacy Rule. http://www.hhs.gov/sites/default/files/privacysummary.pdf
- 14.Voltage Security: Voltage secure stateless tokenization. https://www.voltage.com/wp-content/uploads/Voltage_White_Paper_SecureData_SST_Data_Protection_and_PCI_Scope_Reduction_for_Todays_Businesses.pdf