The most secure and private way to send files over the internet.
Transfer Me It moves files from one Mac to another. They are encrypted before they leave your machine, and only the Mac you sent them to can open them.
otter-quartz-lantern
-
01
Ask for words
Your Mac gives you three words. Give them to whoever is sending. Ask for new ones and the old ones stop working immediately.
-
02
They send
They type your three words and pick what to send; a folder is zipped first. Their Mac encrypts it with your public key before anything is uploaded.
-
03
It arrives
Your Mac checks the bytes against their digest, unseals the key with your private key, decrypts the file and saves it. Then it tells the server to delete the copy, which happens immediately.
The server holds ciphertext it cannot read.
Every file gets a fresh random 256-bit key, generated on the sender's Mac. The body is encrypted there with that key, before it leaves the machine. That part is symmetric encryption, which is fast enough for a file of any size.
That key is then encrypted to the recipient's public key, so only the recipient's Mac can open it. That part is public key encryption, which is slow but needs no shared secret, and a key is small enough for it to carry.
What the server keeps is a public key, an opaque sealed header, the encrypted bytes and a digest of them. It cannot decrypt anything it stores.
Each Mac works out four safety words on its own, by hashing both public keys and the transfer id. Read them to the other person: if anything swapped a key on the way, the two sets differ. Transfers are deleted after 24 hours.
Here is the code. Host it yourself.
The client and the server are both open source. Read them, then run the server on your own machine and point the app at it.
It is one field in Settings. Nothing above changes when you do, because none of it depends on our server being honest.
A menu bar app for macOS. No account, no email, no password. Your identity is a key pair in your Mac's Keychain.