Encryption
How PinkyBond encrypts messages and calls
Everything she shares with you is encrypted on her phone and decrypted on yours. Our server forwards sealed envelopes it cannot open. We never hold the key.
Built on platform cryptography
We did not write our own crypto. On iPhone we use Apple's CryptoKit. On Android we use Google's Tink. Curve25519 key agreement, HKDF-SHA256 and AES-256-GCM on both, pinned to each other by shared test vectors, so an iPhone and an Android phone produce byte-for-byte identical ciphertext.
Key agreement
Curve25519 (X25519) ECDH
Encryption
AES-256-GCM
Key derivation
HKDF-SHA256
What we do, and what we don't
Every row is checkable. The last three are where we fall short of the best messengers, and we would rather you read that here than find it out later.
| Dimension | PinkyBond |
|---|---|
| Encryption | AES-256-GCM, end-to-end between the two phones |
| Key agreement | Curve25519 (X25519) ECDH, then HKDF-SHA256 |
| Implementation | Apple CryptoKit on iPhone, Google Tink on Android — byte-for-byte interoperable |
| Key storage | iOS Keychain / Android Keystore, hardware-backed where available |
| Pairing | QR code in person, or a 6-character code / link exchanged remotely; both public keys exchanged |
| Verification | A 6-digit code on both phones confirms no one sat in the middle |
| Account | None — no phone number, no email, no password |
| Pristup servera sadržaju poruka i poziva | Nikakav. Nikada ne čuvamo ključ. |
| What the relay stores | ID uparivanja, tip poruke, vremenska oznaka, veličina, šifrovani tekst — briše se čim je isporučeno, najviše 30 dana |
| Fotografije, video snimci i fajlovi | Do 2 GB, zapečaćeno novim ključem za svaki fajl koji imaju samo vaša dva telefona; briše se čim se preuzme, najviše 30 dana. Partnerskoj aplikaciji koja još nije ažurirana: do 25 MB pod ključem uparivanja, čuva se 30 dana |
| Evidencija poziva | Koji je telefon zvao, kada, glasovni ili video poziv, ishod i trajanje — čitljivo za naš server, čuva se 90 dana, briše se kada raskinete uparivanje. Nikada zvuk ili slika. |
| Push notifications | Carry no text; the phone decrypts locally |
| Safety Mode | Yes — her phone sends neutral substitute data instead of her real status. Your app shows no indicator, though the flag itself is in the snapshot. |
| Forward secrecy | No — one key per pairing |
| Open source | No |
| Independent audit | Not yet |
How pairing works
No phone number. No email. No account. In the same room, she shows a QR code and you scan it. Apart, she sends you a 6-character code or a link. Either way both phones exchange public keys, derive the same secret, and show a 6-digit verification code so the two of you can confirm no one sat in the middle.
She taps “Pair with partner” in PinkyBloom
Her phone generates a Curve25519 key pair (Apple CryptoKit on iPhone, Google Tink on Android)
She shows a QR code, or sends you a 6-character code or link if you are apart
You scan or enter it in PinkyBond, and your phone generates its own key pair
Your public key travels back to her the same way; both phones now hold both public keys
Each phone runs ECDH and HKDF-SHA256 to derive the same shared secret — nothing secret crosses the network
The shared secret is stored in the iOS Keychain or the Android Keystore
A 6-digit verification code appears on both phones; if they match, no one sat in the middle
The Blind Relay
Naš server je poštansko sanduče za zapečaćene koverte. Čuva šifrovani tekst samo dok ga drugi telefon ne preuzme, a zatim ga briše — najkasnije posle 30 dana, ako taj telefon ostane offline. Nikada ne čuva ključ. Push obaveštenja ne sadrže tekst; telefon dešifruje lokalno.
PinkyBloom
Encrypts on her phone
Blind Relay
Čuva šifrovani tekst do isporuke, najviše 30 dana
Cannot decrypt
PinkyBond
Decrypts on your phone
Sve što naš server čuva o poruci, fajlu i pozivu:
pairingId
Identifier for the pairing; not a name, number or email
senderRole
Which app sent it: PinkyBloom or PinkyBond
messageType
Koja je to vrsta koverte — na primer poruka u ćaskanju, snimak statusa, potvrda prijema ili uspostavljanje poziva — nikada šta je unutra
timestamp
When it was sent
ciphertext
AES-256-GCM blob we cannot open; its length is the only thing we can measure
retention
Briše se čim ga drugi telefon primi; najviše 30 dana ako ostane offline
relayReceipts
Nakon isporuke, zapis bez sadržaja: koja je to poruka bila i da li je isporučena ili je istekla. Čuva se 30 dana, da bi telefon pošiljaoca mogao da prikaže „nije isporučeno”
mediaObjects
Fotografije, glasovne poruke, video snimci i fajlovi do 2 GB, sačuvani na Cloudflare R2 kao šifrovani tekst pod novim ključem za svaki fajl koji putuje samo unutar šifrovane poruke. Briše se čim ga telefon tvoje partnerke preuzme; najviše 30 dana
callLog
Koji je od dva telefona zvao, kada, glasovni ili video poziv, primljen, propušten ili odbijen, i koliko je trajao. Čitljivo za naš server — tako telefon koji je bio ugašen ipak sazna za propušten poziv. Čuva se 90 dana, briše se kada raskinete uparivanje. Nikada zvuk ili slika
Calls
Voice and video are peer-to-peer WebRTC with DTLS-SRTP and fresh keys for every call. The call setup rides the encrypted relay like any message. Before media flows, your phone checks the peer's DTLS fingerprint against a key derived from the pairing secret; a failed check aborts the call.
Kada mreža blokira direktan put, relej prosleđuje pakete koje ne može da pročita. Nijedan medijski server nikada ne čuje poziv, i nijedan poziv se ne snima. Radi između iPhone-a i Androida. Ono što naš server čuva je evidencija poziva — koji je telefon zvao, kada, glasovni ili video poziv, ishod i koliko je trajao — 90 dana, da bi partner čiji je telefon bio ugašen ipak video propušten poziv. Više na /calls.
Safety Mode
Encryption protects her data from outsiders and from us. Safety Mode is for the case where the person on the other end is the concern. She can pause sharing at any time, and he is never notified. She can also turn on Safety Mode, which substitutes neutral data he cannot distinguish from a real update.
When Safety Mode is active, the partner sees:
Phase
“Follicular”
Mood
“Good”
Energy
3 (Moderate)
The neutral data is encrypted and sent through the normal relay, so it looks the same as a real update in transit and on his screen.
Questions
Encrypted between the two phones. We never hold the key.
No phone number, no email, no account. The same cryptography on iPhone and Android, and a relay that forwards ciphertext it cannot open.
