BerryChain

A letter written to one person, carried a long way, and opened by nobody else. BerryChain brings that back.

Write a letter on your phone. It is sealed there, with a key that only the person you are writing to holds, and carried by a public blockchain of volunteer miners. They can see that a letter went from one address to another. They cannot read a word of it. The recipient opens it whenever they next look: today or in a month. No accounts, no sign-up, no servers holding your mail, and an option to burn a letter for good with rotating keys.

WHAT THE APP DOES
• Creates a wallet on your phone, sealed with a passphrase, with twelve recovery words that rebuild it anywhere. Open it with Face ID or Touch ID if you like; the passphrase still rules.
• Claims your starter: a few BERRY from the network's treasury, and a name so people can write to you. No form, no approval.
• Writes and reads sealed letters, with a small photo if you like, kept in a folder per friend. A letter shows the moment it reaches the network, before its block.
• Parcels: attach a file up to 100 MB, sealed on your phone, fetched and checked by the recipient, and deleted when the letter is burned.
• Crews: write one letter to a group of friends, and everyone in the crew can reply to all.
• Contacts: everyone you have corresponded with, by name, plus anyone you add by address, checked against the chain as you type.
• Receiving keys that rotate every month, so a burned letter stays burned.
• Sends and receives BERRY, with a QR code for your address.
• Notifications when a letter arrives.
• Opens on your letters or on your chest, as you prefer.
• The Harbourmaster: a pen pal who answers every letter and keeps a small purse. A welcome tip for your first letter, a letter of the week, and a bonus for pen pals who go on to mine a block.

ABOUT BERRY
BERRY is the stamp on the envelope: a unit of account on this network that pays the miner a tiny fee for carrying a letter. It has no price, no exchange and no promise of value, and the app does not sell it. You earn it by taking part: a starter when you join, more as you correspond with more people.

HONEST NOTES
• This is pre-audit software from a small project. Do not keep anything on it you cannot afford to lose.
• The ledger is public and permanent: addresses, times and sizes of letters are visible to anyone; their contents are not.
• Your keys never leave your phone. Lose the passphrase and the words and nobody can help.

Open source, MIT licence: github.com/Keysersoze1991/berrychain