"The Teenager's Library of Alexandria": The Skyblog Mass Shadow Archival, Informational Dispossession, and the Post-Quantum Accountability Gap in GDPR Rights Against Inalienable Public Archives

This paper study documents the exercise of data subject rights under Articles 14, 15, 17 and 21 GDPR against the Bibliothèque nationale de France (BnF), arising from the mass archival of approximately 12.6 million Skyblog personal internet sites following the platform's closure in August 2023. This case study introduces two concepts: shadow archival - the institutional collection of personal data under statutory authority that operates outside the practical reach of data subject rights - and informational dispossession - the compounded condition in which those rights are formally available but structurally inoperable through architectural foreclosure and temporal incapacity. The analysis maps nine compliance frictions (F1–F9) in the BnF's handling of the access request, and applies a legal analytics framework adapted from Restrepo & Charlotin to assess descriptive, diagnostic, predictive, and prescriptive dimensions of the case. The paper further identifies a quantum accountability gap: the legally unresolved convergence of archival inalienability under Article 17(3)(d) GDPR, pseudonymisation dependency, and post-quantum cryptographic vulnerability through the Harvest Now, Decrypt Later (HNDL) strategy. This dimension is advanced as a research proposition rather than a legal finding, drawing on Commission Recommendation C(2024) 1801 on post-quantum cryptography transition, CJEU Grimaldi (C-322/88), and NIST FIPS 203/204/205, and is identified as a priority question for subsequent research at the intersection of archival law, data protection, and post-quantum cryptographic governance. Note on scope. This paper originated as a graded assignment for the Data Law course at the Université Libre de Bruxelles (ULB) taught by Professor David Restrepo-Amariles and Professor Sébastien Meeùs. The post-quantum dimension was developed independently by the author after the course submission deadline and does not form part of the assessed coursework. No external funding was received.