Where your secrets really live.
Every Hongi check rests on standard cryptography and one habit: we say plainly which secret lives where. This page covers all three products, what holds if Hongi is hacked, and the limits of any spoken code.
- Hosting
- Amazon Web Services, EU region (Ireland)
- Keys
- AWS Key Management Service, separate keys per purpose
- Directory
- Signed with ECDSA P-256; the app accepts only the production key
- Audit
- Tamper-evident hash chain; daily signed snapshots in test
- Codes
- New every 30 seconds; two different codes per check
- Never received
- Call audio, call content, colleague secrets, private device keys
Five rules everything else follows
The secret is never spoken
People read short codes derived from a secret. The secret itself is never shown, typed, spoken or sent.
Codes expire in 30 seconds
Each code is computed for the current 30-second slot; a checker accepts one slot either side for clock drift. A recorded code is worthless within about a minute and a half.
Two different codes
Each side says a different code and expects the other’s. Hearing one side doesn’t reveal the other.
Every product is separated
Every relationship has its own secret, so a code from one is never valid in another.
Secrets where they belong
Between two people or two colleagues, only on their two phones. Where many agents speak for an organisation, Hongi holds its copy, encrypted under a managed key.
Standard building blocks: X25519, HKDF-SHA512, HMAC-SHA512, Ed25519, ECDSA P-256, AES-256-GCM and XChaCha20-Poly1305, from the widely used open-source noble libraries, shared by server and app.
Where the secret lives
Hongi Work was designed so that no server can compute a colleague’s code. Where an organisation speaks through many agents, Hongi holds the organisation’s side, and says so.
| Question | Hongi Anyone | Hongi Customers | Hongi Work |
|---|---|---|---|
| Who checks whom | Anyone checks your organisation; you see a returning pseudonymous phone | You and a named customer check each other | Named colleagues check each other, and can check a team |
| Where the secret lives | The person’s phone, and Hongi’s server encrypted with a managed key | The customer’s phone, and Hongi’s server encrypted with a managed key | Only on the two phonesNo server, Hongi’s included, holds or can compute the codes |
| Who computes your organisation’s codes | Hongi, for your organisation’s agents only | Hongi, for your organisation’s agents only | There is no organisation side: each colleague’s phone computes its own |
| Needs a connection | Staff yes; the person no, after adding you | Staff yes; the customer no | No; removals are checked when online |
| Codes | 6 digits, every 30 seconds | 6 digits, every 30 seconds | A word and three digits, or 6 digits, every 30 seconds |
| Status | Live | Available for pilots | Available for pilots |
What runs where
Keys in AWS KMS
Separate keys per purpose: a root signing key per organisation for Hongi Work, a master key that wraps organisation pairing data (each unwrap bound to its organisation), audit keys and the directory signing key. Signing happens inside KMS; the keys can’t be exported.
A signed directory
The list of organisations reaches phones signed with ECDSA P-256 by a key in KMS. The app checks it against the production key built into the app; test keys are not accepted, so a tampered list is rejected.
A tamper-evident audit log
An append-only, hash-chained audit log. A daily snapshot signs its head with a KMS key (ECDSA P-256), chains it to the day before and keeps it seven years in write-once storage, so standard OpenSSL can check it against Hongi’s public key. The daily snapshot is in test.
Hosted in the EU
Amazon Web Services, EU region (Ireland). Test and production are separate environments with their own databases, encryption keys and storage.
Network
A web application firewall in front of the application and sign-in endpoints, and default-deny network policies around production services.
On the phone
Secrets in the platform keystore, on this device only and never restored to another device. Adding an organisation requires Apple App Attest or Google Play Integrity. Hongi Work screens have their own lock.
What if Hongi’s servers are hacked?
The question every security team should ask. The answer differs per product, so here it is per product: what holds, and what doesn’t.
A leak yields no secrets; your codes are computed by Hongi
- A database leak alone yields no pair secrets: they are stored only encrypted
- The operations dashboard has no rights to decrypt pairing material
- Whoever fully controls the signing service and its key rights could compute organisation-side codes. Limited operationally, not cryptographically
- The signed directory protects phones in normal operation; it is not a promise against someone who controls Hongi’s systems
A leak yields no secrets and no names; your codes are computed by Hongi
- A database leak alone yields no pair secrets or customer names: both are stored only encrypted
- The operations dashboard has no rights to decrypt pairing material
- Whoever fully controls the signing service and its key rights could compute organisation-side codes. The signing service runs separately and is the only service granted that key
The server can’t compute your colleagues’ codes
- No colleague codes: they need a private work key that exists only on the phones
- No past secrets: none are stored
- No rollback: phones refuse an older revocation list
- A phone that can reach your domain refuses any organisation key other than yours
- Enrolling a forged phone under a real colleague’s name. The colleague’s own phones ask “Was this you?”, unless the attacker withholds that too
- Re-signing a colleague’s certificate with another display name or role label; phones show “Name changed from …” for 30 days
- Re-signing an old revocation list again and again, so that new removals don’t reach phones
- Not covered: a phone set up for the first time while the attacker also blocks your domain, or an organisation not in the directory
Limits that apply to every spoken code
| Limit | What it means and what we do |
|---|---|
| Real-time relay | Someone on two calls at once (pretending to be Tom to Sarah and Sarah to Tom) can pass codes across within 30 seconds. No spoken code can prevent this. The defence is procedural and taught in the app: check on a call you placed to a number you know, and say why you are calling before you read codes. |
| No forward secrecy | Keys are long-lived so checks work offline and need no pairing. A stolen device key works until the phone is revoked or its certificate expires (30 days at most); it cannot renew itself. Past codes are useless after about 90 seconds. |
| An unlocked phone in the wrong hands | Out of scope for any app. Hongi Work screens have their own lock (Face ID, fingerprint or passcode), and a lost phone should be removed straight away. |
| Guessing | A random guess at a colleague code succeeds about 1 in 333,000 times for six digits, and 1 in 217,000 for a word and three digits, against a colleague with one phone. The app allows only a few attempts a minute and locks after repeated failures. |
What is live, in test and planned
Until the external review, all reviews of Hongi are internal. We don’t claim certifications.
| Component | Status |
|---|---|
| Hongi Anyone: the verified directory, signed directory, app attestation when someone adds an organisation | Live |
| Signed daily audit snapshot: hash chain, head signed with a KMS key, seven years write-once | In test |
| Hongi Customers: named customers | Available for pilots |
| Hongi Work: colleague verification and role identities | Available for pilots |
| Company sign-in with Microsoft Entra ID, SCIM provisioning | In test |
| Your own root key in your own AWS key management; key rotation | Planned |
| Self-service audit export with chain verification | Planned |
| Independent review of the cryptography and architecture by an external firm | Planned |
| Information-security management working towards ISO/IEC 27001 | Planned |
Updated October 2026. Available for pilots: running on our servers; the app version that includes it is in test (TestFlight and Google Play beta), not yet in the stores.
What Hongi never receives
Hongi never receives personal or colleague codes, colleague secrets, private device keys, call audio or call content. For organisation pairs (Hongi Anyone and Hongi Customers), Hongi computes the organisation’s codes from the encrypted pair secret, for that organisation’s agents only. Hongi is never part of the call; the app only shows codes.
Hongi Work is a personal safety tool, not a monitoring tool: there is no report of individual checks, and the audit log never records who checked whom.
Controller and processor
For Hongi Customers, you are the controller of your customers’ names and Hongi is the processor. Names are encrypted under a key used for your organisation alone and never appear in audit records. The portal asks you to accept a Data Processing Agreement before you invite customers; its final text is being prepared, and we share the draft on request.
Sub-processors include Amazon Web Services (hosting, Ireland) and Expo, which passes push notifications to Apple’s and Google’s push services.
Found a vulnerability?
Email us what you found and how to reproduce it, and give us time to fix it before you publish.