A forgery attack on the Block.co blockchain-based digital credential certification system

2026-06-30

AI Summary

This study addresses a critical vulnerability in existing blockchain-based academic credential verification systems, such as Block.co, which lack a trustworthy mechanism to securely bind an educational institution’s real-world identity to its digital counterpart. The authors present the first practical forgery attack against such systems, exploiting the disconnect between blockchain immutability and identity validation logic to generate fraudulent credentials that are erroneously validated as legitimate. This work exposes a fundamental flaw in decentralized credentialing models—namely, the insecure identity-binding process—and demonstrates that this weakness introduces systemic security risks across similar platforms. The proposed attack methodology is generalizable, highlighting a pervasive threat that undermines the integrity of blockchain-issued digital credentials and offering crucial insights for the secure design of future systems.

Abstract

Certification of digital documents, such as academic credentials, seems a particularly suitable application for the use of blockchain and distributed ledger technologies. Indeed, these technologies enable decentralized certification systems that rely on the immutability and persistence of their distributed ledgers. However, in the absence of a central trusted authority, it is not easy to guarantee the authenticity of the connection between the real identity of an academic institution and the digital identity of the certificate issuer. In this paper, we demonstrate that one of such systems, known as Block.co, has a vulnerability that allows the production of forged certificates that are recognized as valid by the system. Since this is an inherent limitation of the approach used for blockchain-based certification, our attack is likely to be extendable to other systems adopting the same approach.

Problem

• blockchain
• digital credentials
• forgery attack
• identity verification
• decentralized certification

Innovation

• blockchain-based certification
• digital credential forgery
• identity binding vulnerability
• decentralized authentication
• certificate validation