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2025
 Díaz-Sánchez, Daniel;  Campo, Celeste;  García-Rubio, Carlos
Zero‑Trust Token Authorization with Trapdoor Hashes for Scalable Distributed Firewalls Journal Article 
In: pp. 18, 2025.
Abstract | Links | BibTeX | Tags: blind signatures, decentralized authorization, Discovery, I-Shaper, IoT, Qursa, Ramones, TLS Integration
@article{danieldiaz030,

title = {Zero‑Trust Token Authorization with Trapdoor Hashes for Scalable Distributed Firewalls},

author = {Daniel Díaz-Sánchez and Celeste Campo and Carlos García-Rubio },

url = {https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5313600},

doi = {http://dx.doi.org/10.2139/ssrn.5313600},

year  = {2025},

date = {2025-08-31},

urldate = {2025-08-31},

pages = {18},

abstract = {Massive Internet of Things (IoT) deployments expose networks to severe risks, as a single compromised device can facilitate lateral movements across the entire infrastructure. Traditional firewalls, based on static rules, are fragile, difficult to synchronize across domains, and poorly suited for Zero Trust principles. In this work, we propose a scalable authorization architecture where each flow carries a cryptographically protected textit{token} that incorporates a signed and immutable policy, verifiable in a non-interactive manner. The textit{tokens} are issued based on attestation evidence, and the messages are reinforced using trapdoor textit{chameleon hashes}, which allows for flexible delegation and transferability without invalidating the original policy. Through key aggregation techniques, we enable collaborative issuance, optional anonymity, and multi-party governance. The experimental evaluation in a real textit{testbed} demonstrates that the verification of this embedded authorization incurs a fixed and predictable cost—higher than that of rule lookups, but constant regardless of network size, rule growth, or concurrency. This balance eliminates the burden of distributing and maintaining large rule tables while ensuring granular per-flow authorization, privacy preservation, and interoperability between providers. The proposal materializes a Zero Trust model resistant to impersonation, replay, and lateral attacks, and lays the groundwork for future optimizations through the progressive incorporation of post-quantum primitives.},

keywords = {blind signatures, decentralized authorization, Discovery, I-Shaper, IoT, Qursa, Ramones, TLS Integration},

pubstate = {published},

tppubtype = {article}

}

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Massive Internet of Things (IoT) deployments expose networks to severe risks, as a single compromised device can facilitate lateral movements across the entire infrastructure. Traditional firewalls, based on static rules, are fragile, difficult to synchronize across domains, and poorly suited for Zero Trust principles. In this work, we propose a scalable authorization architecture where each flow carries a cryptographically protected textit{token} that incorporates a signed and immutable policy, verifiable in a non-interactive manner. The textit{tokens} are issued based on attestation evidence, and the messages are reinforced using trapdoor textit{chameleon hashes}, which allows for flexible delegation and transferability without invalidating the original policy. Through key aggregation techniques, we enable collaborative issuance, optional anonymity, and multi-party governance. The experimental evaluation in a real textit{testbed} demonstrates that the verification of this embedded authorization incurs a fixed and predictable cost—higher than that of rule lookups, but constant regardless of network size, rule growth, or concurrency. This balance eliminates the burden of distributing and maintaining large rule tables while ensuring granular per-flow authorization, privacy preservation, and interoperability between providers. The proposal materializes a Zero Trust model resistant to impersonation, replay, and lateral attacks, and lays the groundwork for future optimizations through the progressive incorporation of post-quantum primitives.
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https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5313600
doi:http://dx.doi.org/10.2139/ssrn.5313600
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