Digital Signature Chains for Secure Document Exchange in ERP-Based Procurement Workflows

Abstract

Procurement workflows in modern enterprises involve the continuous exchange of critical documents
such as purchase requisitions, purchase orders, goods receipts, and invoices. However, conventional ERP-based
communication channels often lack end-to-end authenticity guarantees, making documents vulnerable to tampering,
impersonation, and unauthorized modification. This study proposes a digital signature chain (DSC) framework
integrated with SAP S/4HANA to ensure secure, immutable, and verifiable document exchange throughout
procurement lifecycles. The proposed approach employs multi-level digital signatures, cryptographic hashing, and
blockchain anchoring to preserve the integrity and provenance of each document state transition. A lightweight
blockchain audit layer is implemented externally to anchor document fingerprints, while the ERP system manages
workflow logic and metadata propagation. A functional prototype was developed and validated using SAP Business
Technology Platform (BTP), demonstrating improved traceability, non-repudiation, and regulatory compliance over
traditional ERP mechanisms. Results show that DSC integration introduces minimal latency (below 190 ms per
transaction) while providing strong assurance against forgery and unauthorized changes. The study concludes that
digital signature chaining significantly enhances trust, transparency, and governance in procurement ecosystems,
making it especially useful for regulated industries where document integrity and auditability are critical.