The increasing use of digital documents has created a growing need for mechanisms that can ensure the authenticity and integrity of information. Digital documents can be modified without leaving physical evidence of alteration, making cryptography-based validation mechanisms necessary. This study designs and implements a digital document validation mechanism by integrating an Ed25519-based digital signature with a Visual Cryptography Sharing Scheme. Ed25519 is used to generate and verify digital signatures based on a private and public key pair. The document hash value is used as a representation of the data to be signed so that even minor modifications to the document can affect the verification result. Visual Cryptography is used to divide authentication information into several shares so that the complete information cannot be obtained from a single share. The study applies a research and development approach consisting of requirements analysis, system architecture design, implementation, and functional and security testing. The testing scenarios include original documents, modified documents, invalid signatures, incomplete shares, and share reconstruction. The proposed design demonstrates that Ed25519 can serve as an authentication and document integrity mechanism, while Visual Cryptography can provide an additional layer for distributing validation information. The main contribution of this study is the integration of these two mechanisms into a unified digital document validation process. The developed system can serve as a basis for securing academic documents, administrative documents, certificates, electronic letters, and other digital documents that require authenticity verification.