Authors:
S. Rogit, K. N. Nawaz Sheriff, B. Mahesh Bala, V. Nivedita

Addresses:
Department of Computer Science and Engineering, SRM Institute of Science and Technology, Ramapuram, Chennai, Tamil Nadu, India.

Abstract:

When it comes to secure document collaboration in organisational settings, access control is not enough; it also requires end-to-end traceability of every activity that is performed on a document during its entire lifecycle. Researchers introduce TrustFlow, a full-stack framework that integrates cryptographic chain-of-custody (CoC) tracing, steganographic watermarking, Shamir threshold secret sharing, time-lock encryption, and tamper-evident audit logging into a unified document collaboration platform. TrustFlow is a full-stack framework. TrustFlow constructs a hash-linked provenance tree for each document. Within this tree, each node corresponds to an Ed25519-signed state transition, which may include uploading, sharing, revoking, or deleting. Forensic leak identification is made possible by the utilisation of three complementary steganographic watermarking modes: zero-width Unicode, linguistic synonym replacement, and whitespace encoding. All recipients are guaranteed that their documents will be destroyed in a verifiable manner using a deletion-cascade engine equipped with signed tokens and replay prevention. PostgreSQL serves as the system's database, with a Fast-API backend and a React frontend. Additionally, researchers provide an outline of a staged roadmap to complete decentralisation through the use of abstract backend interfaces, blockchain anchoring, and threshold-gated access controls.

Keywords: Chain-of-Custody; Document Traceability; Steganographic Watermarking; Shamir Secret Sharing; Time-Lock Encryption; Tamper-Evident Logging; Access Control Lists.

Received on: 28/03/2025, Revised on: 25/05/2025, Accepted on: 02/09/2025, Published on: 12/06/2026

DOI: 10.69888/FTSCS.2026.000684

FMDB Transactions on Sustainable Computing Systems, 2026 Vol. 4 No. 2, Pages: 78-96

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