Digital Signature Signer & Verifier
Sign documents or text with a private key and verify cryptographic digital signatures with the matching public key.
1 How to Use the Digital Signature Signer & Verifier
To Sign: Provide private key and text message, click 'Sign Message' to produce cryptographic signature in Base64.
To Verify: Provide public key, text message, and signature, click 'Verify Signature'.
Or click 'Generate Sample Keys & Test' for an instant 1-click demonstration.
Confirm validity: Signature passes (green) or fails tamper detection (red).
2 Technical Specifications
| Specification | Details & Capabilities |
|---|---|
| Algorithms | ECDSA (P-256 with SHA-256) and RSASSA-PKCS1-v1_5 |
| Signature Format | Base64 and Hexadecimal |
| Verification Status | Tamper-evident mathematical verification |
| Engine | Web Crypto API (crypto.subtle.sign / verify) |
Trust and Privacy
100% Client-Side Privacy Guarantee
All calculations run directly in your local browser memory. Zero data is ever transmitted, logged, or stored on remote servers.
4 Frequently Asked Questions
Q. What does a digital signature prove?
A digital signature proves two essential things: Authenticity (the message was signed by the private key holder) and Integrity (the message was not modified in transit by even 1 character).
Q. What happens if someone modifies the signed message?
Even changing a single comma or space will cause mathematical verification to immediately fail, warning the recipient of tampering.