Proving Identity

Cryptography · Axiom Academy

How do you prove you are who you claim to be in the digital world? Click on different authentication methods to explore how we prove identity in everyday life. Adjust the security level to see how cryptographic authentication is different from traditional methods. Click "Send Challenge" to see how a server can verify your identity without ever learning your secret. Click "Sign Document" to see how digital signatures provide authentication and non-repudiation. Why non-repudiation matters in the real world. Alice claims: "I never authorized that transaction!" With password authentication, Alice could claim someone else learned her password. The server has no proof it was really her. Alice claims: "I never signed that transaction!" With digital signatures, the transaction has cryptographic proof that Alice's private key created it. Since only Alice has her private key, she cannot deny signing it. This provides legal accountability. Cryptographic authentication lets you prove you know a secret without ever exposing it, unlike passwords which must be stored and transmitted. Random challenges prevent replay attacks. Each authentication session is unique, so old responses can't be reused by attackers. Public key cryptography provides authentication, integrity verification, and non-repudiation—all without requiring secure channels. Mathematical proof of identity provides legal accountability. You can't deny actions signed with your private key.

This is the written version of the interactive lesson above. See the full Cryptography course.