Hidden Photo — send a photo only they can see

The idea

One picture. Two realities.

The cover image is what the world sees — in the chat, on a camera roll, in a backup. The real photo only ever appears inside PrivateMark, for the one person who shares your passphrase.

What everyone seesThe cover — in the chat, on their camera roll, everywhere.

🔓

What your contact seesThe real photo — only in PrivateMark, only with your shared passphrase.

Step by step

Four steps — and three of them happen once.

01 · PAIR

Pair, in person

You and your contact set a four-word passphrase once — scan a QR or read the words aloud. Nothing secret ever travels with your photos again.

02 · CHOOSE

Pick photo & cover

Choose the real photo to hide and an innocent cover. PrivateMark builds one picture that looks like the cover.

03 · SEND

Send it anywhere

Share it like any photo — a chat, AirDrop, email. To everyone it's just the cover image.

04 · REVEAL

They reveal it

Your contact opens it in PrivateMark and the real photo appears — watermarked to them, so a leak still traces back.

Two ways to send

File mode stays on your phone. Photo mode survives any chat.

📴

File mode

MAXIMUM PRIVACY

The real photo travels inside the file itself. Nothing leaves your device — no cloud, no servers, ever.

✓AirDrop, Mail, Files, “send as Document”
✓100% offline & zero metadata anywhere
–Not through inline chat photos (they'd recompress it)

💬

Photo mode

SEND THROUGH ANY CHAT

Send a normal-looking photo through WhatsApp, iMessage and more. The real photo is stored end-to-end encrypted in your own iCloud and fetched by your contact.

✓Survives chat-app recompression
✓Shows a real photo thumbnail in the chat
–Needs iCloud; a small encrypted copy lives ~2 weeks, unreadable without your passphrase

Is it safe?

Sealed with encryption only the two of you can open.

✓Only your passphrase opens it. The real photo is protected with AES-256 — the same class of encryption banks and governments rely on.
✓Not us. Not Apple. Not the chat app. Whoever stores or carries the file only ever sees unreadable ciphertext and an innocent cover.
✓The passphrase never travels with the photo. You set it once, in person — so intercepting a message gives an attacker nothing.
✓Watermarked on reveal. The recovered photo is marked to the person who opened it, so a leak still points to a name.

We're honest about the limits. This is concealment plus end-to-end encryption — not a magic trick. The hidden data is detectable to forensic file inspection, so we never claim it's “undetectable.” What we claim is that nobody without your passphrase can open it. File mode leaves nothing anywhere. Photo mode keeps a short-lived encrypted copy in your own iCloud so the picture can survive a chat app's recompression — Apple hosts ciphertext it cannot read.

Some photos are meant for one person.

Hidden Photo is part of PrivateMark — on iPhone, iPad and Mac.