W4-007 · Condition 02 — Portable identity
Credential portability
Credential portability is the property that an attestation issued on one surface can be presented and verified on another, without the verifier contacting the issuer or the holder losing control of what is disclosed.
If the verifier has to phone the issuer, you have built a lookup, not a credential.
The practical test is offline verification. A credential that requires the verifier to call the issuer’s API is a permission check wearing a credential’s clothes: the issuer remains in the loop, can revoke silently, and learns every place the holder goes.
Real portability means the attestation carries its own proof. The verifier checks a signature against a known issuer key, the holder chooses what to reveal, and the issuer learns nothing about where it was used.
For a founder this is the difference between an identity layer they can build on and one they are a tenant of. The distinction is invisible in a demo and decisive at scale.