Keys and authorization

Mementom lets you sign in and approve actions without handing over your name, phone number or an email tied to your identity.

You create digital keys by pairing pictures with captions. Your digital keyring is the saved collection you use across your devices.

When a site asks you to prove you have access, Mementom picks a key at random, shows its picture and asks for the matching caption. We call that request a challenge.

Who controls what

One keyring connects your keys to the permissions companies grant you.

A person owns and controls their keyring; companies own apps and define challenges; Mementom manages permission grants and randomly selects an eligible key for each challenge. Full explanation below.

Read the diagram

You own and control your keyring.: Add, edit, replace, share or remove keys. Each key pairs an image with a caption. Your images stay on your device.
The company controls its apps and challenges.: It defines actions, such as signing in or authorizing home entry, and issues permissions for its apps and challenges.
Mementom checks the proof and permissions.: For each challenge, Mementom randomly selects an eligible key, shows its image and asks for its matching caption. It checks permissions and their limits before returning a scoped approval or rejection.
Identity-free access control.: Permission records retain no name or email tied to your identity. Identity-free email uses a separate mailbox and controlled delivery records. The company receives an app-specific reference, never the global keyring ID or your key images and captions.

A challenge, step by step

Follow a home-entry request from Aster through the secure Mementom window and back to the company.

Six-step challenge flow: Aster starts a request, opens Mementom, sends its private details directly to the window, Mementom checks the key proof and returns a signed approval, then Aster authorizes the action. Full explanation below.

Read the six steps

The company starts a request. Aster asks for permission to authorize home entry.
A secure Mementom window opens. The company page opens a separate window using a short-lived, service-issued URL.
Aster provides the request details. Private details come directly from Aster into its part of the window. They do not pass through Mementom’s service.
You answer the challenge. Mementom randomly selects an eligible key from your keyring. You see its image and enter the matching caption. The image stays on your device; Mementom checks the derived image code and caption.
Mementom returns the result. After checking the proof and permissions, it returns a signed result scoped to this request. The diagram shows the approval path.
The company acts on that result. Aster validates and consumes the approval before authorizing home entry.