Meet the cast
Every character in Keystone plays a part that real security people talk about every day. Learn the character, and you have learned the role.
Relying party
The castle's IT guy. Dry, kind and always underestimated. He has never built a kingdom's trust system before; neither has anyone else. He pushes his glasses up before every check, and he answers every question of the Royal Exam.
In real PKI: A relying party is whoever decides whether to trust something: it checks signatures, certificates and chains before it believes them. Your browser is a relying party every time it opens an HTTPS page.
Key holder
She will be crowned in thirty days. Quick, funny, impatient with ceremony, and never the one who needs rescuing. She hosts the Royal Exam, and her signet ring goes everywhere with her.
In real PKI: A key holder owns a private key and keeps it secret. She signs with it and asks for certificates that bind her name to her public key. Later in the story she runs the kingdom's own certificate authority.
Man-in-the-middle and impostor
A quick-change artist who wants the crown. Her disguise as Rosa is perfect, down to the long black hair, so you can never tell them apart by looking.
In real PKI: A man-in-the-middle sits between two people and swaps or fakes their messages. Mallory never breaks the maths. She tricks people into trusting the wrong key, which is exactly what certificates are there to stop.
Eavesdropper
Gramophone horns for ears and a shelf of jars full of recorded messages. She listens to everything and changes nothing.
In real PKI: An eavesdropper is a passive attacker: she reads and records traffic but does not alter it. Encryption is what keeps her recordings useless, as long as nobody can later recover the keys that protected them.
Forger
An ink blob in a beret who can copy the look of any document, seal and all. Comic relief, mostly.
In real PKI: A forger fakes how a document looks. He cannot fake a digital signature, because the signature depends on the exact content and on a private key he does not have. The maths catches him every time.
Certificate authority
The Royal Notary, with spectacles on a chain and ink on his cuffs. When the kingdom needs someone to vouch for keys, he takes the job.
In real PKI: A certificate authority (CA) checks who controls a name and then signs a certificate saying "this public key belongs to this name". Everyone who trusts the CA can then trust the key.
Cryptographers really use these names. When they describe an attack, Eve is the eavesdropper who only listens and Mallory is the attacker who changes messages. In the game, villains show attacks only as story moments, never as real tools or step-by-step methods.