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ISO/IEC SC 27 is the arena where international crypto standards are conceived. We work within ISO for a world that offers better security and better privacy to the global industry, gov-related institutions and above all, to users.

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Dr. Pascal Paillier

Pascal Paillier , PhD

Senior Cryptography Expert


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Towards trustworthy and privacy-respecting authentication.

ABC4Trust is an EU-funded research initiative that uses cryptographic technologies to provide better protection of privacy and identity on the Internet.


The upcoming standards for new cryptography technologies such as Homomorphic Encryption and Attribute-Based Entity Authentication are expected to revolutionize the security business at a global scale in the mid-term future.


ISO is the ‘‘United Nations’’ of standards, where member countries join forces to issue international standards that cover critical aspects of our lives. The mission of subcommittee 27 (SC 27) IT Security Techniques is to cover the various areas pertaining to security and privacy, split into 5 complementary missions:

  • Working Group 1 - Information security management systems.
  • Working Group 2 - Cryptography and security mechanisms.
  • Working Group 3 - Security evaluation, testing and specification.
  • Working Group 4 - Security controls and services.
  • Working Group 5 - Identity management and privacy technologies.

ISO/IEC 18033-6 ‘‘Homomorphic Encryption’’

CryptoExperts CEO Dr. Pascal Paillier is the main editor of the upcoming WG 2 standard on Homomorphic Encryption, that is, encryption that supports computing over encrypted data. Driven together with co-editor Prof. Atsuko Miyaji from the Japan Advanced Institute of Science and Technology (JAIST), this project intends to add a new part to ISO/IEC 18033 ‘‘Encryption algorithms’’:

  • ISO/IEC 18033 Part 1 - General.
  • ISO/IEC 18033 Part 2 - Asymmetric ciphers.
  • ISO/IEC 18033 Part 3 - Block ciphers.
  • ISO/IEC 18033 Part 4 - Stream ciphers.
  • ISO/IEC 18033 Part 5 - Identity-based encryption.
  • ISO/IEC 18033 Part 6 - Homomorphic encryption.

The standard intends to specify approved encryption mechanisms that support one single homomorphic operation i.e. either addition or multiplication of plaintexts over a prescribed domain. Informative material such as guidance to implement them as well as a description of practical use-cases will also be included as informative annexes.

Homomorphic encryption that supports one operation, sometimes referred to as ‘‘partially homomorphic’’ as opposed to ‘‘fully homomorphic’’ encryption (FHE) that supports universal computations in the encrypted domain, is powerful enough to secure a wide range of applications in the cloud computing sector. Finance and health are typical business areas where homomorphic encryption is expected to open the way to revolutionary solutions.

Study Period ‘‘Attribute-based Entity Authentication’’

Dr. Pascal Paillier is also the main rapporteur of an ongoing study period within WG 5 Identity management and privacy technologies, the goal of which is to standardize attribute-based entity authentication mechanisms. These mechanisms allow users to authenticate towards a verifier (aka. service provider or relying party) in a way that reveals only partial information about them, just the minimal amount that is strictly required by the verifier’s policy. This approach allows to replace commonly used authentication mechanisms, which currently lead to risks of over-identification and identity theft, by mechanisms that enforce minimal disclosure and therefore obey the data minimization principle.

Privacy-preserving authentication

An example of such mechanisms are Attribute-Based Credentials (ABCs also known as privacy-ABCs). The terminology ABC refers to a family of cryptographic systems where a user (or user agent thereof) collects once and for all a credential from some authority known as an Issuer and later presents a randomized version of that credential to a verifier when claiming legitimate access to their service. In a nutshell, this randomization renders transactions anonymous (untraceable and unlinkable) and protects the anonymity of users against all strategies of traceability, even performed by colluding authorities. If needed, an entity role known as inspector (aka. opener) can be added to an ABC system to reveal the identity of particular users in case of legal dispute. Similarly, a role of revocation authority can be added to the system to support credential revocation in a cryptographically strong sense.

ABC technologies, in particular Microsoft’s U-Prove and IBM’s IdentityMixer, have been the main focus of the EU project ABC4Trust, featuring CryptoExperts as an active partner.

Reshaping the future of transactions

These mechanisms are an important part of Privacy Enhancing Technologies (PETs) and show what the future of entity authentication will most likely be: the right balance between user anonymity and policy enforcement, with the collateral effect of putting user consent back into central position. This paradigm shift is expected to reshape the nature of transactions on the long run in a wide range of business sectors, and therefore requires standardized, mature, interoperable, efficiently implementable mechanisms at its core.