What mintBlue is
The envelope model in one screen. Who seals, who carries, who opens, and what the record proves afterwards.
Two organisations that need to exchange data have a choice between two bad options. Pool everything in a shared database, and whoever runs that database becomes the gatekeeper. Keep everything apart, and nobody can prove later what was sent, when, or by whom.
mintBlue takes the postal route instead.
Everyone seals their own envelope
Each party holds its own keys. The content is encrypted and signed on your side, before it goes anywhere, and it leaves your system already sealed. mintBlue carries the envelope and records that it was carried. The addressee opens it.
Sealing is a per-record decision rather than a blanket promise. An output
submitted with encryption switched off is readable by anyone who fetches the
record, exactly as a postcard is. The Quickstart sets both
sign and encrypt on the first record it submits, and
Non-custodial keys sets out precisely which key
does what, and what mintBlue holds in each deployment model.
What the record proves
Two properties survive the delivery, and they are the reason the postal comparison is worth making.
The envelope is signed, so the addressee can check who sealed it without asking mintBlue to vouch for anyone. And the delivery is anchored to a shared record that no single party controls or can rewrite, so the fact that a record existed in a given form at a given moment is checkable afterwards by anyone holding the proof. The public audit layer covers what that buys you, and what it deliberately does not promise.
Where mintBlue fits
The addressing, the sealing and the recording are specified by an open protocol, which anyone can read and anyone can implement. mintBlue can run that implementation for you, together with the parts that are tedious to operate: the infrastructure, the connection to the audit layer, and the SDK that does the cryptographic work on your side.
mintBlue and the SDX Protocol explains that split, and what it means for the organisation on the other end of the envelope.