Source-linked AI summary
ZK-eSIM: A Privacy-Centric Zero-Knowledge Approach for eSIM Provisioning
Liza Ahmad, Quan Shi, Joshua Haworth, Yilu Dong, Prosanta Gope, Behzad Abdolmaleki, Syed Rafiul Hussain
TL;DR
Conventional eSIM provisioning exposes persistent identifiers that let infrastructure link otherwise independent provisioning events. ZK-eSIM replaces those disclosures with zero-knowledge proofs and session-scoped credentials, and its authors report anonymity and unlinkability guarantees with a prototype practical within the existing GSMA ecosystem.
Problem
Persistent identifiers in provisioning can link events to the same eUICC and, when associated with account records, to a subscriber.
Source: §1 · p. 2Method
ZK-eSIM combines zero-knowledge proofs, one-time credentials, and per-session pseudonyms, with joint authorisation for identity recovery.
Source: §1 · p. 2Results
The prototype demonstrates provable subscriber anonymity and provisioning-session unlinkability while retaining accountable traceability within the existing GSMA ecosystem.
Source: §11 · p. 14Takeaways & Limitations
A Java Card applet prototype on a test eUICC, integrated with a modified SM-DP+ and LPA, shows the guarantees are practical within existing GSMA roles and interfaces.
Source: §11 · p. 14ZK-eSIM addresses provisioning-layer privacy but leaves cross-protocol risks after profile installation and IP address deanonymisation out of scope.
Source: §10 · p. 13
Abstract
from arXiv · showhide
GSMA Remote SIM Provisioning (RSP) enables over-the-air delivery of eSIM profiles, but it exposes long-lived identifiers during profile ordering and download. In particular, stable device identifiers (e.g., EID), profile identifiers, and long-lived certificate material enable mobile operators and profile-delivery infrastructure to link provisioning events to the same eUICC and, when combined with account records, to the same subscriber. This undermines subscriber anonymity and enables cross-session tracking. We present ZK-eSIM, a privacy-preserving redesign that achieves subscriber anonymity and provisioning-session unlinkability while retaining accountable traceability by exception. ZK-eSIM (i) replaces direct disclosure of device identifiers with a zero-knowledge proof of device validity and eligibility; (ii) enforces session unlinkability through short-lived, one-time pseudonymous credentials and per-session identifiers to prevent cross-session tracking; and (iii) provides privacy-preserving accountable traceability through a jointly authorised escrow mechanism, so that no single entity can unilaterally deanonymise a user. We formalise a multi-entity, honest-but-curious threat model and prove subscriber anonymity and the unlinkability of provisioning sessions under standard cryptographic assumptions. We implement a Java Card applet on a test eUICC to evaluate performance on commodity hardware with a modified LPA and SM-DP+ server. Our experiments quantify end-to-end cryptographic overhead relative to conventional RSP, confirming that ZK-eSIM adds only practical overhead, closing a critical privacy gap while preserving deployability within existing GSMA roles and interfaces.
1 Introduction
Conventional RSP reuses stable device and certificate identifiers, allowing provisioning events to be linked to an eUICC and potentially its subscriber. ZK-eSIM redesigns the workflow for anonymity and session unlinkability while retaining jointly authorised traceability.
1 Introduction
- The EID and persistent certificate material let provisioning infrastructure recognise the same device across sessions and link downloads to subscriber records.At subscription, the operator and SM-DP+ learn the EID with account data; reused identifiers can link otherwise separate profile downloads.Source: §1 · p. 2
- The privacy gap matters as profile switching grows: a persistent EID can connect short-lived travel profiles and their provisioning records.The passage notes an 85% increase in travel eSIM usage in 2025 and stable EID mappings across otherwise independent events.Source: §1 · p. 2
- The paper frames three questions: whether provisioning can protect subscriber anonymity, unlink sessions across operators, and retain accountable traceability.The stated privacy goal is to avoid revealing real-world identity or permanent device identifiers and to keep distinct provisioning sessions unlinkable.Source: §1 · p. 2
- ZK-eSIM uses fresh per-session pseudonyms and zero-knowledge proofs, with one-time credentials that prevent application-layer and certificate-based linkage.Identity recovery requires joint authorisation by the MNO and a designated LEA, while routine provisioning remains anonymous and unlinkable.Source: §1 · p. 2
2 Background and Related Work
GSMA Consumer RSP uses eUICC and SM-DP+ certificates to authenticate devices and protect profile delivery, while identifiers such as EID and ICCID identify the device and profile. Prior work and standards emphasize delivery security; ZK-eSIM adapts established cryptographic techniques to provide privacy across the complete RSP workflow.
2 Background and Related Work
- The GSMA trust infrastructure uses certificate chains for mutual authentication and to bind protected profile packages to the intended eUICC.The MNO authorises issuance, while the SM-DP+ prepares, stores, and delivers the protected profile package.Source: §2 · p. 3
- EID identifies the eUICC, ICCID identifies a profile, and Matching ID helps the device retrieve a pending profile.The workflow begins with the device providing its EID during subscription, then proceeds through order, authentication, and profile download.Source: §2 · p. 3
- GSMA specifications and prior analyses focus on correctness, authentication, and secure delivery, leaving subscriber anonymity and unlinkability outside their main goals.Ahmed et al. confirm that RSP delivery guarantees do not provide subscriber anonymity or unlinkability; the transparency proposal still depends on stable identifiers.Source: §2 · p. 3
- ZK-eSIM composes established techniques for the complete, stateful RSP workflow and integrates them with GSMA trust and operational infrastructure.The paper distinguishes this end-to-end adaptation from frameworks aimed at individual authentication tasks and cellular privacy work focused on 5G authentication.Source: §2 · p. 4
3 Privacy Risks in Conventional RSP
Conventional RSP exposes stable identifiers at subscription, across profile downloads, and during certificate authentication, creating linkability risks. ZK-eSIM focuses on the non-primary deployment model, where a third-party or multi-tenant SM-DP+ can correlate activity across operators.
3 Privacy Risks in Conventional RSP
- At subscription, an operator receives the EID with account and KYC data, linking the eUICC to a real-world subscriber.The resulting association can connect other operator-side identifiers and account records to the same person.Source: §3 · p. 4
- Reusing the EID lets operators or profile servers connect separate downloads, and certificate-chain material can preserve that link even if the EID is hidden during ordering.The risks comprise identity–EID binding at subscription (R1), cross-session and cross-operator linkability (R2), and certificate-chain fingerprinting (R3).Source: §3 · p. 4
- A multi-tenant SM-DP+ can join provisioning requests across operators by their reused EID, connecting profile activity to one device.The paper focuses on non-primary deployment, where the SM-DP+ is distinct from the home MNO and creates a new observation point.Source: §3 · p. 4
- Travel eSIM use makes repeated provisioning a recurring setting for these risks, while shared backends can expose EID-to-ICCID mappings.The passage describes reseller dashboards exposing provisioning state and notes that shared services can observe requests across operators and times.Source: §3 · p. 5
- Rotating the factory-programmed EID would require difficult hardware-rooted redesign, while preloading profiles is constrained and leaves the EID exposed.ZK-eSIM keeps the EID and profile-storage model intact and shifts privacy protection to the protocol layer.Source: §3 · p. 5
4 System Model, Threat Model, and Design Goals
ZK-eSIM models the provisioning ecosystem as mutually untrusted entities and addresses privacy risks from parties that follow the protocol but may analyse their views. Its design preserves RSP delivery protections while adding anonymity, session unlinkability, and jointly authorised traceability.
System Model
- The model includes the UE, MNO, SM-DP+, PCA, LEA, and GSMA PKI, with eUICC secrets protected and local LPA–eUICC communications authenticated.The PCA issues short-lived per-session certificates; the LEA participates only in lawful de-pseudonymisation.Source: §4 · p. 5
Threat Model
- The model assumes non-collusion among separately operated entities; primary deployments where an MNO operates its own SM-DP+ are treated as colluding.It also assumes TLS-protected communications, uncompromised keys and trust anchors, and hardware-protected eUICC keys; physical extraction, denial of service, and global cross-domain traffic correlation are out of scope.Source: §4 · pp. 5–6
- MNO, SM-DP+, and PCA are honest-but-curious: each executes prescribed operations but may use its legitimate view to link sessions or identify users.The MNO sees subscriber onboarding records; the SM-DP+ sees profile and delivery records; the PCA sees certificate requests and eligibility proofs.Source: §4 · p. 6
Design Goals
- ZK-eSIM retains secure communication and profile confidentiality while targeting unlinkable authentication, subscriber anonymity, provisioning-session unlinkability, and accountable traceability.De-anonymisation requires LEA–MNO cooperation under legally authorised conditions; no single entity can deanonymise unilaterally.Source: §4 · p. 6
- Conventional Consumer RSP meets DG1 and DG3 but falls short on the privacy and accountability goals DG2 and DG4–DG6.The design-goal comparison distinguishes baseline security goals retained from RSP from ZK-eSIM’s novel privacy and accountability goals.Source: §4 · p. 6, Table 1 · p. 6
5 High-level Overview of ZK-eSIM
ZK-eSIM replaces stable identifiers in provisioning with eligibility proofs, fresh session credentials, pseudonyms, and escrowed identity. Its phases support unlinkable provisioning for the MNO and SM-DP+ while retaining settlement and lawful traceability by exception.
5 High-level Overview of ZK-eSIM
- Registration establishes an unlinkable eligibility credential once; each later provisioning session begins with a fresh certificate and key pair.The eUICC obtains a short-lived pseudonym certificate from the PCA before requesting a profile.Source: §5 · p. 7
- The UE’s profile request combines a challenge-derived pseudonym, escrowed EID, pseudonym certificate, and zero-knowledge proof of correct formation and same-eUICC binding.The MNO verifies the proof and challenge freshness without learning a stable identifier.Source: §5 · p. 7
- After order authorisation, the SM-DP+ checks session-bound credentials and a single-use token before mutual authentication and encrypted profile delivery.A repeat profile request loops back to certificate initialisation with fresh session credentials; Figure 4 presents the protocol’s high-level phases.Source: §5 · p. 7, Figure 4 · p. 7
- Under a valid legal order, de-pseudonymisation requires the LEA and MNO to cooperate to decrypt the escrowed identity and resolve the subscriber.Settlement reconciles redeemed tokens against prior authorisations without persistent identifiers.Source: §5 · p. 7
- Fresh certificates, pseudonyms, and one-time authorisation bundles for each profile yield session unlinkability for MNO and SM-DP+ views under the paper’s threat model.The workflow preserves operational settlement and lawful traceability by exception.Source: §5 · p. 7
6 Preliminaries for ZK-eSIM
The paper introduces cryptographic notation and non-interactive zero-knowledge, then formalises ZK-eSIM as a sequence of provisioning, settlement, and accountable de-anonymisation algorithms. The scheme is stated to achieve provisioning-session unlinkability and unforgeability.
6 Preliminaries for ZK-eSIM
- The preliminaries define the paper’s cryptographic notation, including probabilistic algorithms, uniform sampling, and negligible functions.Additional background is deferred to Appendix A.Source: §6 · p. 7
6.1 Non-Interactive Zero-Knowledge
- A non-interactive zero-knowledge argument lets a prover convince a verifier of a statement’s validity without leaking beyond that validity, using one message and a common reference string.The paper specifies completeness, zero-knowledge, and knowledge soundness.Source: §6.1 · p. 7
6.2 ZK-eSIM: Definitions
- ZK-eSIM is formalised as algorithms and protocols for setup, registration, certificate initialisation, pseudonymous requests, profile ordering, provisioning, settlement, and de-anonymisation.Correctness requires the user to obtain the intended profile, the token to be recorded exactly once, and the MNO and SM-DP+ to obtain consistent logs and receipts.Source: §6.2 · p. 8
- Registration issues an unlinkable eligibility credential; certificate initialisation creates a fresh session key pair and short-lived pseudonym certificate.The request protocol attests in zero knowledge that the pseudonym, escrow, and eligibility credential are correctly formed and bound to the same eUICC without revealing its EID.Source: §6.2 · p. 8
- The MNO authorises a hashed pseudonym and returns a credential and one-time token; the SM-DP+ checks their bindings, records token use, and delivers the profile.The download protocol outputs an acceptance flag; settlement reconciles authorisation and spent ledgers, while de-anonymisation requires a valid warrant and LEA–MNO cooperation.Source: §6.2 · p. 8
- ZK-eSIM is stated to achieve provisioning-session unlinkability and unforgeability.The paper refers to its formal security analysis for these properties.Source: §6.2 · p. 8
7 ZK-eSIM Construction
ZK-eSIM replaces persistent identifiers in provisioning with eligibility proofs, fresh pseudonyms, and session-bound credentials. Its workflow retains profile delivery and accountable traceability while requiring cooperation to resolve a session to an EID.
7 ZK-eSIM Construction
- At registration, the eUICC proves correct formation of a blinded request and receives a blind-signed, device-bound eligibility credential without revealing its underlying values.The user presents EID for eligibility and KYC; the device-sealed bootstrap secret binds issuance to that eUICC.Source: §7 · p. 9
- For each provisioning session, the eUICC proves its fresh hardware-bound key belongs to the eligibility-checked device, and the PCA issues a time-bounded pseudonym certificate.The certificate is freshly initialised for each session to preserve multi-session unlinkability.Source: §7 · p. 9, Figure 7 · p. 9
- Fresh per-session pseudonyms replace the long-lived EID in profile ordering, while download authorisation is bound to a fresh session and one-time release token.The flow follows the GSMA Activation Code control flow with modified semantics, using Hpid as the session-scoped Matching ID or activation token.Source: §7 · p. 9
- The MNO verifies a zero-knowledge request proof that binds device eligibility, a challenge-derived pseudonym, and an EID escrow ciphertext without revealing those values.The fresh nonce supports unlinkability across sessions; the MNO learns a pseudonym and proof of hardware continuity and eligibility.Source: §7 · p. 9
- The order and download phases turn pseudonymous authorisation into a one-time, session-bound profile download with authenticated key establishment and protected profile delivery.The SM-DP+ verifies eligibility and rejects a reused token; the eUICC verifies the profile package and installs the profile.Source: §7 · p. 10
- After installation, ordinary enable, disable, and delete operations remain unchanged and local, while backend management can use a profile-scoped alias rather than re-exposing EID.The design also leaves the standard 5G-AKA procedure unchanged after provisioning.Source: §7 · pp. 10–11
- For lawful resolution, the MNO stores the EID escrow ciphertext, which the LEA can decrypt for a specific session under a valid, scoped warrant and joint cooperation.The MNO learns identity during registration and can resolve the recovered EID to the corresponding KYC record; provisioning-layer anonymity does not hide registration identity.Source: §7 · p. 11
8 Security Analysis
The security analysis establishes provisioning-session unlinkability and order-side and download-side unforgeability under stated cryptographic assumptions. The results cover the MNO, SM-DP+, and PCA as potential observers.
8 Security Analysis
- ZK-eSIM achieves provisioning-session unlinkability for MNO, SM-DP+, and PCA if the NIZK, commitments, KDF, PRF, random-oracle, encryption, and pseudonym-certificate assumptions hold.The theorem bounds adversarial advantage in terms of the total random-oracle queries to H′ and H′′.Source: §8 · p. 11
- MNO-side unforgeability follows under NIZK knowledge soundness, anonymous-credential unforgeability, hash collision resistance, and fresh MNO challenges.The property concerns accepted order-side provisioning state.Source: §8 · p. 11
- SM-DP+-side unforgeability follows under credential and one-time-token security, hash collision resistance, and correctness of the stateful spent-token check.The property concerns accepted download-side provisioning state.Source: §8 · p. 11
9 Implementation and Evaluation
ZK-eSIM was implemented on a test eUICC with modified GSMA-compliant LPA and SM-DP+ components. The evaluation reports higher cryptographic runtime than commercial RSP alongside bounded server memory and linear load scaling.
9.1 Testbed Setup and GSMA Integration
- The testbed uses a Java Card applet on a test eUICC, modified GSMA-compliant LPA and SM-DP+ components, and an additional PCA server.The evaluation setup uses a PC running Ubuntu 22.04 with an 8-core Ryzen 7 CPU and 64 GB RAM for server-side operations.Source: §9.1 · p. 12, §9 · p. 12
9.2 Implementation and Deployability
- ZK-eSIM adds six request-response message pairs and optional ASN.1 fields, with about 628 lines of SM-DP+ code and about 6.7K lines for the custom applet.It is offered as an optional workflow alongside commercial RSP; existing profile applets may reduce real-world applet code, while the PCA certificate service requires a change or separate offering.Source: §9.2 · p. 12
9.3 End-to-End Cost Comparison
- 98.199 seconds versus 53.660 seconds: ZK-eSIM’s cryptographic processing time is approximately 83% higher than commercial RSP.Considering only phases within commercial RSP, the reported increase is approximately 64%; Table 2 presents mean and standard deviation over 25 runtimes.Source: §9.3 · pp. 12–13, Table 2 · p. 13
9.4 Server Scalability of ZK-eSIM
- 998 ± 9 MB at the SM-DP+, 1006 ± 7 MB at the MNO, and 1008 ± 8 MB at the PCA: peak memory remains closely clustered at large request scale.The server-load evaluation extends toward 1,000,000 concurrent download requests; memory remains bounded and load scales linearly with requests served.Source: §9.4 · p. 13, Figure 11 · p. 13
- 2,843.6 s at the MNO versus 234.8 s at the SM-DP+ and 111.5 s at the PCA: average CPU time for serving 1,000,000 requests is concentrated at the MNO.The passage attributes this to the MNO’s EC-based Schnorr identity-proof verification.Source: §9.4 · p. 13
10 Discussion
ZK-eSIM focuses on provisioning-layer privacy and does not address cross-protocol risks that persist after a profile is installed.
10 Discussion
- The design leaves post-installation cross-protocol risks and IP-address deanonymisation outside its scope.Future work includes routing transparency, IP anonymisation, constrained profile behaviour, and resilient lifecycle management.Source: §10 · p. 13
11 Conclusion
ZK-eSIM replaces persistent identifiers in Consumer RSP with zero-knowledge proofs and session-specific credentials, while retaining accountable traceability and the existing GSMA ecosystem. Its formal definitions specify unlinkability and unforgeability goals for provisioning.
11 Conclusion
- ZK-eSIM uses zero-knowledge proofs, single-use pseudonym certificates, and per-session pseudonyms to provide subscriber anonymity and session unlinkability while retaining accountable traceability.The prototype combines a Java Card applet on a test eUICC with modified LPA and SM-DP+ components.Source: §11 · p. 14
A Additional Preliminaries
- Pedersen commitments are perfectly hiding and computationally binding under the discrete-logarithm assumption and unknown log_g u.The commitment is C(m;r) = g^r u^m; producing distinct valid openings would recover log_g u.Source: §A.0.1 · p. 16
A.1 ZK-eSIM Construction: Notation and Interfaces
- The construction’s notation defines interfaces for zero-knowledge proofs, pseudorandom functions, encryption, and commitments.These conventions are used to describe the protocol algorithms.Source: §A.1.1 · p. 16
B Algorithms
- The algorithms initialise per-card secrets and authorization logs, issue credentials, and accept download tokens only once after checking their bindings.The MNO records authorized pseudonyms, while the SM-DP+ records spent tokens.Source: B Algorithms · pp. 16–18
- Escrow traceability is triggered by a valid legal warrant and scope; the LEA decrypts the selected EID, and the MNO verifies the escrow record before resolving it to KYC information.The returned identity is directed to the lawful process.Source: B Algorithms · p. 18
C Game-based Definition
- The security definitions require negligible unlinkability advantage across MNO, SM-DP+, and PCA views, and negligible order-side and download-side forgery advantages.The unlinkability game excludes timing and packet-size metadata; unforgeability covers unauthorized requests and downloads.Source: C Game-based Definition · pp. 18–19
D.1 Proof of Theorem 1
The proofs establish provisioning-session unlinkability through hybrids that remove identity-dependent transcript fields, then analyze unauthorized MNO requests through soundness, credential, freshness, and binding cases.
D.1 Proof of Theorem 1
- The unlinkability hybrid proof simulates proofs, randomizes pseudonyms and hashes, makes pseudonym certificates independent of device identity, and replaces escrow ciphertexts with encryptions of zero.The remaining credentials, tokens, and authorization logs have the same distribution for either challenge bit when generated from fresh session randomness and session-local values.Source: §D.1 · pp. 19–20
D.2 Proof of Theorem 2
- The MNO-side unforgeability proof partitions accepting unauthorized requests into cases involving false proofs, forged credentials, freshness violations, or inconsistent bindings.The cases reduce to violations of proof soundness, credential security, nonce freshness, or hash collision resistance.Source: §D.2 · p. 20, §D.1 · p. 20
D.3 Proof of Theorem 3
The SM-DP+ proof addresses unauthorized or replayed downloads by separating authorisation forgery, token forgery, token reuse, and hash-rebinding cases.
D.3 Proof of Theorem 3
- The SM-DP+ proof covers unauthorized or replayed downloads through cases for forged authorisation credentials, forged tokens, replayed spent tokens, and hash rebinding.The proof identifies signature forgery, failure of the spent-token check, or hash collisions as the corresponding failure conditions.Source: §D.3 · p. 20
E Collusion Analysis
Collusion analysis shows that privacy degrades according to which infrastructure roles combine records, while protocol security checks and provisioning correctness remain intact. The paper also provides reproducibility artefacts and describes ethical safeguards and evaluation boundaries.
E Collusion Analysis
- Without collusion, the MNO retains the Phase 0 subscriber–EID mapping, while fresh session values keep the SM-DP+ and PCA from receiving that identity or linking sessions.DG1–DG6 and provisioning correctness hold.Source: E Collusion Analysis · p. 21
- MNO–SM-DP+ and MNO–PCA collusion both enable repeat-session association and bypass DG6, while SM-DP+–PCA collusion links certificate issuance to one session but preserves DG1–DG6.In the SM-DP+–PCA case, the combined view lacks the MNO’s subscriber–EID record and a persistent cross-session identifier.Source: E Collusion Analysis · p. 21
- Full infrastructure collusion links the subscriber to the pseudonym certificate, profile request and order, ICCID, and provisioning session, causing DG2, DG4, DG5, and DG6 to fail.DG1, DG3, and provisioning correctness remain.Source: E Collusion Analysis · p. 21
- Authorisation, one-time-token, authenticated-key, and profile-confidentiality checks remain performed in every collusion case, preserving DG1, DG3, and provisioning correctness.An authorised profile is installed on the intended eUICC, tokens are accepted only once, and MNO and SM-DP+ records remain consistent.Source: E Collusion Analysis · pp. 21–22
F Open Science
- The authors provide a modified GSMA-compliant SM-DP+ server, an extended LPA, and a Java Card applet to support reproduction and further work.The artefacts are made available in the project repository.Source: F Open Science · p. 22
G Ethical Considerations
- The evaluation is limited to a controlled testbed with test eUICCs and modified open-source RSP components; real deployment requires operator, standards-body, and jurisdiction-specific legal review.The study uses no production carrier infrastructure, carrier secrets, subscriber telemetry, or human-subject data.Source: G Ethical Considerations · p. 22