> For the complete documentation index, see [llms.txt](https://davidjosearaujo.gitbook.io/notes-mcs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://davidjosearaujo.gitbook.io/notes-mcs/identification-authentication-and-authorization/identity-management/self-sovereign-identity-ssi.md).

# Self-Sovereign Identity (SSI)

It requires a digital wallet.

* For keeping digital credentials.
* Credentials are Verifiable Credentials that can prove to a verifier:
  * Who is the issuer
  * To whom they were issued
  * Whether it has been altered since it was issued
  * Whether it has been revoked by the issuer

## Types of credentials

Third-party attested credentials.

* The credentials a person shows to others to prove their identity attributes.
* They imply the trust of the credential receiver in the credentials’ issuers.
  * Usually verified through cryptographic means.

Self-attested credentials.

* What I say about myself.
  * Opinion, preference, consent.
* Still needs credentials issued by TTPs.
  * To associate identity attributes recognized by others to your opinion, preference or consent.

## Credential issuers

They act in response to requests of credentials’ owners.

* And not the services they access.

They can change/revoke issued credentials at any time.

* But credential owners can still use them.
* Revocation verification should not require contact with the credential issuer.
  * Some public repositories must exist (blockchain).

## P2P sessions

Each entity possesses a wallet, which contains an asymmetric key pair.

Thus, each pair of entities can establish a secure, P2P “connection”, or “session”. With which they can securely exchange credentials