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Quickstart

Install 

go install github.com/madstone-tech/cipher/cmd/mdstn-cipher@latest

See Installation for Docker and prebuilt-binary options.

Encrypt a file for yourself

No setup needed — the first time you encrypt, Cipher auto-generates a default key.

mdstn-cipher encrypt secret.pdf
# → secret.pdf.mdstn

The .mdstn file uses streaming AES-256-GCM and is safe to store or move anywhere.

Decrypt a file 

mdstn-cipher decrypt secret.pdf.mdstn --output secret.pdf

The encryption method is auto-detected from the file header.

Encrypt with a passphrase (no stored key) 

mdstn-cipher encrypt secret.pdf --passphrase

You’ll be prompted for the passphrase; decryption prompts for it again.

Encrypt for someone else by email

Cipher looks up the recipient’s public key via CKD and encrypts so only they can open it.

mdstn-cipher encrypt invoice.pdf --for alice@team.com

Next steps