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 |
| Serverens adgang til besked- og opkaldsindhold | Ingen. Vi har aldrig nøglen. |
| What the relay stores | Parrings-id, beskedtype, tidsstempel, størrelse, krypteret tekst — slettes så snart den er leveret, højst 30 dage |
| Billeder, videoer og filer | Op til 2 GB, forseglet med en ny nøgle pr. fil, som kun jeres to telefoner har; slettes så snart den er downloadet, højst 30 dage. Til en partner-app, der endnu ikke er opdateret: op til 25 MB under parringsnøglen, gemt i 30 dage |
| Opkaldslog | Hvilken telefon der ringede, hvornår, tale eller video, resultatet og varigheden — læsbart for vores server, gemt i 90 dage, slettet når I ophæver parringen. Aldrig lyden eller billedet. |
| 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
Vores server er en postkasse til forseglede kuverter. Den holder på krypteret tekst, kun indtil den anden telefon henter den, og sletter den så — efter højst 30 dage, hvis den telefon forbliver offline. Den har aldrig en nøgle. Push-beskeder indeholder ingen tekst; telefonen dekrypterer lokalt.
PinkyBloom
Encrypts on her phone
Blind Relay
Holder på krypteret tekst indtil levering, højst 30 dage
Cannot decrypt
PinkyBond
Decrypts on your phone
Alt hvad vores server gemmer om en besked, en fil og et opkald:
pairingId
Identifier for the pairing; not a name, number or email
senderRole
Which app sent it: PinkyBloom or PinkyBond
messageType
Hvilken slags kuvert det er — for eksempel en chatbesked, et statusøjebliksbillede, en kvittering eller en opkaldsopsætning — aldrig hvad der er indeni
timestamp
When it was sent
ciphertext
AES-256-GCM blob we cannot open; its length is the only thing we can measure
retention
Slettet så snart den anden telefon modtager den; højst 30 dage hvis den forbliver offline
relayReceipts
Efter levering, en post uden indhold: hvilken besked det var, og om den blev leveret eller udløb. Gemt i 30 dage, så afsenderens telefon kan vise “ikke leveret”
mediaObjects
Billeder, talebeskeder, videoer og filer op til 2 GB, gemt på Cloudflare R2 som krypteret tekst under en ny nøgle pr. fil, der kun rejser inde i den krypterede besked. Slettet så snart din partners telefon har downloadet den; højst 30 dage
callLog
Hvilken af de to telefoner der ringede, hvornår, tale eller video, besvaret, mistet eller afvist, og hvor længe det varede. Læsbart for vores server — det er sådan en telefon, der var slukket, alligevel finder ud af et mistet opkald. Gemt i 90 dage, slettet når I ophæver parringen. Aldrig lyd eller billede
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.
Når et netværk blokerer den direkte vej, videresender et relæ pakker, det ikke kan læse. Ingen medieserver hører nogensinde et opkald, og intet opkald optages. Det virker mellem iPhone og Android. Det vores server gemmer, er en opkaldslog — hvilken telefon der ringede, hvornår, tale eller video, resultatet og hvor længe det varede — i 90 dage, så en partner, hvis telefon var slukket, alligevel ser det mistede opkald. Mere på /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.
