Identity at the City Gate

Imagine you are travelling to a city with very strict entry rules.

It is not enough to say, “Hello, I’m here to help.” The guard at the gate needs to know who you are, whether you belong to a recognised group, and whether you are actually allowed to do what you say you are there to do.

This is exactly the problem we face in financial settlement networks. Before participants move funds, they need a reliable way to prove their identity and their authority.

Here is how we solve that using decentralised identity—explained without the jargon.

The Traveller: You and your DID

First, the guard needs to know they are talking to the same person who was issued the pass.

Instead of showing a passport that someone else printed, you have a unique "Traveller’s Mark." This mark is linked to a set of keys that only you control. By performing a simple action with your private key, you can prove the mark is yours.

In the technical world, this is a Decentralised Identifier (DID). It’s an ID that you own and control, rather than one held in a central database.

The Guild: Your trusted authority

Next, the guard asks: "Who says you’re a merchant?"

In our story, a Guild is a trusted authority—such as a regulated institution, recognised issuer, regulator or professional body. They are the only ones allowed to vouch for your skills or your status. You can't just write "I am a Banker" on a piece of parchment; it has to be signed by a Guild the city already trusts.

This Guild is the Issuer. They don't just know you; they have verified your credentials and "stamped" them with their own unique seal.

The Pass: Your Verifiable Credential

The Guild gives you a signed pass. This pass doesn't tell the guard your whole life story; it just proves one specific thing—for example, that you are a "Licensed Diamond Merchant."

In technical terms, this is a Verifiable Credential (VC).

Because the Guild signed it with their own digital seal, the guard can verify it’s real in seconds. They don't have to send a messenger back to the Guild’s headquarters to check. They just look at the signature and the rules in their own city handbook.

The System: Hyperledger Aries and ACA-Py

For any of this to work, every gate and every guild has to follow the same rules — and there must be a public record that anyone can check.

Hyperledger Aries provides the rules: the agreed-upon protocols that define how travellers, guards, and guilds exchange information and verify passes. But there is also the ledger itself — a publicly readable record book where recognised guilds register their official seals. Any guard can check this record to confirm a seal is genuine without contacting the guild directly. This is what "Hyperledger" refers to: distributed ledger infrastructure, like a notary's public register, that no single party controls but everyone can trust. RTGS.global writes each participant's identity to this ledger — maintained by Indicio — as part of onboarding, ensuring only recognised participants can interact on the network. (Aries protocols)

ACA-Py — short for Aries Cloud Agent, Python — is the trained representative who handles gate interactions on your behalf. Think of it as a licensed courier who is fluent in the official gate language, holds your passes in a secure wallet, and manages the formal proof exchange every time you approach a gate. You decide where to go and what authority to claim; ACA-Py handles the paperwork and the cryptographic handshake. (ACA-Py)

Where RTGS.global fits

At RTGS.global, we use these exact patterns. We use ACA-Py to handle the cryptographic "seals" and Aries to handle the communication. Our system acts as the "Controller," making the high-level decisions while the identity layer handles the proof.

This means that, when a participant joins our network, their RTGS.global ID is more than a name in a database: it is a cryptographically verifiable identity that can provide evidence of recognised network membership and authority. Whether that evidence authorises a particular action remains a decision of the applicable trust framework and platform policy.

The Reality Check

The city gate is secure because the rules are clear. The technology provides the evidence, but the "Trust Framework"—the city's rulebook—determines which Guilds are trusted and which passes get you through the gate.

Ready for the non-fantasy version? Read our technical deep dive: Trusted Participant Identity.