What Is Tamper-Evident File Authentication?

Tamper-evident file authentication is a way to check whether a signed file still matches the state it was in when it was signed.

For WaveSign, the focus is visual files: images and PDFs. The signed output is meant to look visually identical, or close to identical, while carrying an invisible signal that can later be verified.

The problem it solves

Visual files are easy to copy and edit. A small crop, text overlay, brightness change, compression pass, or replacement image can change the meaning of a file without making the workflow obvious.

Traditional metadata can help, but metadata is often separated from the file. Platform audit trails can help, but they depend on the platform still being available and trusted.

WaveSign gives teams another layer: a signed media file plus verification metadata that can be checked later.

How WaveSign authentication works

At signing time:

1. the user uploads an image or PDF
2. the user enters a secret key
3. WaveSign embeds an invisible authenticity signal
4. WaveSign creates verification metadata
5. the user receives the signed file and sig.json

At verification time:

1. the user uploads the signed file
2. the user uploads the matching sig.json
3. the user enters the same secret key
4. WaveSign returns whether the file verifies

The signed media and sig.json are both required.

Tamper-evident does not mean impossible to alter

"Tamper-evident" means a later check can reveal that a file no longer verifies. It does not mean the file cannot be copied, edited, deleted, or replaced.

This language matters. WaveSign should not be marketed as making files impossible to modify. It should be marketed as helping teams detect when a signed file has been modified or no longer matches its verification package.

What makes WaveSign different from a visible watermark

A visible watermark is meant to be seen. It discourages unauthorized use or identifies ownership, but it changes the look of the file.

WaveSign is different. Its signal is intended to be invisible or nearly invisible. The file remains useful for inspection, review, or sharing, while still carrying a verification signal.

What makes WaveSign different from an e-signature workflow

E-signature platforms are built around people signing documents: routing, recipient identity, consent, audit logs, and legal workflow.

WaveSign is built around file integrity. It helps answer whether a signed visual file still verifies. It is not a drop-in replacement for every contract-signing workflow.

Best fit customers

WaveSign is most compelling for teams that rely on visual evidence:

• insurance and claims
• inspections and audits
• construction and field work
• legal evidence preparation
• compliance document control
• media verification and review

These workflows care less about drawing a signature box and more about proving that an image or PDF did not silently change after signing.

Bottom line

Tamper-evident file authentication gives teams a practical way to protect visual integrity. With WaveSign, the core package is simple: signed media, sig.json, and the same key used for verification.