Digital Signatures

Proving who sent a message

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Sign with the private key: $s = h^d \bmod n$; verify with the public key: $s^e \bmod n = h$.
• Any change to the message changes its hash and breaks the signature.
• Certificates chain signatures to keep web connections authentic.

Steps

1. Running RSA backwards
2. Forge a signature?
3. Tampering
4. The padlock in your browser
5. Sign the fingerprint
6. Verify a signature