Synology Cloud Sync encryption/decryption in Go

Overview

A Go library to decrypt/encrypt Synology Cloud Sync files on various Operating Systems (Linux, macOS, Windows).

The file format was originally discovered by @marnix and is summarized in this document.

Command line tool

Installation

Assuming you have the go toolchain installed:

go install github.com/maxlaverse/synocrypto/cli/synocrypto

You can also download pre-compiled binaries from the releases page.

Usage

NAME:
   synocrypto - A cli for encrypting and decrypting Synology Cloud Sync files

USAGE:
   synocrypto [global options] command [command options] [arguments...]

COMMANDS:
   decrypt, d   Decrypts a file
   encrypt, e   Encrypts a file
   metadata, m  Displays the metadata of a file
   version      Prints the version
   help, h      Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --debug     outputs additional debug lines (default: false)
   --help, -h  show help (default: false)

Library

Decryption Usage

encFile, err := os.Open("./my-encrypted-file.jpg")
if err != nil {
      panic(err)
}
defer encFile.Close()

decFile, err := os.OpenFile("./my-decrypted-file.jpg", os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
      panic(err)
}
defer decFile.Close()

decrypter := synocrypto.NewDecrypter(synocrypto.DecrypterOptions{
      Password: "synocrypto",
})

err = decrypter.Decrypt(encFile, decFile)
if err != nil {
      panic(err)
}

Encryption Usage

plainFile, err := os.Open("./my-plain-file.jpg")
if err != nil {
      panic(err)
}
defer plainFile.Close()

encFile, err := os.OpenFile("./my-encrypted-file.jpg", os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
      panic(err)
}
defer encFile.Close()

privateKey, err := ioutil.ReadFile("private.pem")
if err != nil {
      panic(err)
}

encrypter := synocrypto.NewEncrypter(synocrypto.EncrypterOptions{
      Password: "synocrypto",
      PrivateKey: privateKey,
})

err = encrypter.Encrypt(plainFile, encFile)
if err != nil {
      panic(err)
}