The Multiple Dilemmas of zk-SNARKs Identification Technology

In recent years, digital identity systems that use zk-SNARKs technology to protect privacy have become increasingly popular. Various zk-SNARKs identity projects are developing user-friendly software packages, allowing users to prove they have a valid identity without revealing identity details. The number of World ID users employing biometric and zk-SNARKs technology has exceeded 10 million. Digital identity projects in Taiwan, China, and the European Union are also placing greater emphasis on zk-SNARKs technology.

On the surface, the widespread application of digital identity based on zk-SNARKs seems to be a victory for decentralized accelerationism (d/acc). It can protect social media, voting systems, and various internet services from witch attacks and bot manipulation without sacrificing privacy. However, the reality is not that simple; these identity systems still carry risks. This article will elaborate on the following points:

• zk-SNARKs encapsulation has solved many important problems
• However, the identification wrapped in zk-SNARKs still has risks, mainly due to the strict limitation on the "one person one identification" attribute.
• Relying solely on "wealth proofs" to prevent witch attacks is not enough; we need some sort of "identification-like" scheme.
• The ideal scenario is that the cost of obtaining N identifications is N².
• A multi-identity system is the most practical solution, which can be explicit like ( based on social graphs for identification ), or it can be implicit with multiple zk-SNARKs identities coexisting (.

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Limitations of zk-SNARKs Identification Systems

Although zk-SNARKs identification systems can solve many privacy issues, there are still some limitations:

1. True anonymity cannot be achieved. Under the strict "one person, one identification" rule, users may only have a single public identification, which reduces the current level of anonymity.

2. Unable to prevent coercion. Even with zk-SNARKs, users may still be forced to reveal their secret values, exposing all activities.

3. Unable to address non-privacy risks. Edge cases such as stateless individuals, multiple nationalities, and identity forgery still exist, and zk-SNARKs are powerless against these issues.

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The Necessity of Identification Systems

Relying purely on "wealth proofs" to prevent Sybil attacks is not enough to solve all problems; we still need some form of identification system. There are mainly two types of scenarios that require an identification system:

1. Universal Basic Income-like scenario: Assets or services need to be distributed to a broad user base without considering their ability to pay.

2. Governance scenarios: It is necessary to distinguish between "one person controlling a large amount of funds" and "multiple people collectively holding equal amounts of funds", as the latter contains richer information.

This indicates that a strict "one person, one vote" rule is not necessary. For applications similar to universal basic income, what is really needed is to limit the number of identities that can be obtained. For governance-like applications, the core requirement is to determine whether the resources are backed by a single entity or a group with low coordination.

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Ideal State and Multi-Identity System

Theoretically, the ideal state is: the cost of obtaining N identifications is N². This can both limit the power of large entities and prevent the system from being abused.

A multi-identity system can achieve this ideal state. It can be explicit ), such as identity based on social graphs (, or it can be implicit ), where multiple identity providers coexist (. The multi-identity system has stronger anonymity, resistance to coercion, and fault tolerance.

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However, if a certain form of identification market share approaches 100%, the advantages of a multi-identity system will disappear. Therefore, the ideal outcome of the "one person, one identification" project is to integrate with the identification system based on social graphs, providing initial support for the latter.

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