Protect your documents: Create and verify digital signatures for any file format. Use locally generated secure key pairs to ensure document privacy, integrity, and authenticity. Generate secure digital signatures and verify file integrity in three simple steps.See the Application User Guide

1. Create Your Digital Identity (Key Pair)

A Key Pair consists of two linked keys: a Private Key (your secret signing tool) and a Public Key (which others use to verify your signature).

2. Sign a Document

Document Fingerprint (SHA-256): Digital Signature Code (This is the proof of signing):

3. Verify Signature

Load the Original File, the sender’s Public Key, and the Signature Code to confirm integrity.

1. Load Original Document: 2. Public Key Code (Paste the key shared by the signer): 3. Digital Signature Code (Paste the signature code from the .sig file):

About this Digital Signature Tool

This online tool provides a robust solution for digital signature creation and verification, ensuring document security and file integrity without ever transmitting your private data to a server. By leveraging the Web Cryptography API, this application performs all key generation and signing processes directly within your browser. This commitment to client-side processing guarantees that your Private Key—the essential element for signing—remains completely secret and is never transmitted over the internet, offering maximum safety and non-repudiation.

The core function of this document signer is to confirm both the sender’s identity and that the file’s content has not been altered since the moment of signing. This makes our tool the ideal way to verify the authenticity of critical files. It can sign virtually any file type, as the cryptographic process operates directly on the underlying binary data (the file’s content hash), regardless of its format. This includes common formats like PDF, DOCX, XLSX, TXT, JSON, HTML, XML, images (JPG, PNG, GIF), audio/video files (MP3, MP4, MOV), compressed archives (ZIP, RAR), and application/software binaries (EXE, DLL), providing comprehensive tamper-proof protection across all your digital assets.

To verify a signature, only three items are needed: the original file, the signature code (often stored in a .sig file), and the sender’s Public Key. If the verification process confirms validity, you can be certain of the file’s source and integrity. Use this secure document tool today to enhance your data governance and protect your digital communication, making it a critical online tool for anyone needing proof of file authenticity.

Application User Guide: Step-by-Step Instructions

Follow these simple, non-technical steps to sign and verify your files securely:

Part 1: Signing Your Document

1. Generate Keys (Step 1): Click "Generate New Key Pair." This creates your unique Private Key (your secret) and Public Key (for sharing).
2. Save Keys: Immediately download the Public Key (.json). You must share this file with anyone who needs to verify your signatures. You should also securely back up your Private Key (by revealing and downloading the JSON) if you intend to sign documents later or on another device.
3. Load Document (Step 2): Use the file input to select the document you want to sign (e.g., PDF, image, spreadsheet). The app automatically calculates a unique digital fingerprint (SHA-256).
4. Sign Document: Click the "Sign Document" button. The app uses your Private Key to cryptographically sign the document’s fingerprint, generating the Digital Signature Code.
5. Download Artifacts: Click "Download Original File & Signature (.sig)". This gives you the original file and a tiny `.sig` file containing the signature code. Send both of these files, along with your Public Key, to the recipient.

Part 2: Verifying a Signature

1. Load Document (Step 3, Item 1): Upload the Original File received from the signer.
2. Input Public Key (Step 3, Item 2): Paste the signer’s Public Key Code (from their `.json` file) into the text area.
3. Input Signature (Step 3, Item 3): Paste the Digital Signature Code (from the `.sig` file) into the final text area.
4. Verify: Click the "Verify Signature" button. The app uses the Public Key to check if the signature matches the document’s content. If it returns "VALID," you are certain of the document’s source and integrity; if "INVALID," the file has been tampered with or the provided keys/signature are incorrect.