This small CLI program efficiently decrypts files, directory trees, or a stream from stdin encrypted client-side by QNAP's Hybrid Backup Sync (HBS) app.
The program requires the libcrypto library (which is provided by OpenSSL) to be installed on your system.
Also, please be aware that at the moment, the source code only compiles on Unix-like systems,
but adapting it to Windows should not be too hard.
If you do manage to build it on Windows, feel free to submit a pull request!
To compile this program, run:
$ make
Then, you may run
$ ./qnap-hbs-decryptor -h
to print out the following help page on how to use the program:
Usage: ./qnap-hbs-decryptor [-p <pw>] [-m <mem>] [-t <tmp>] [-v] [file/dir...]
Options:
-p <password> The password you have set when creating the HBS backup job.
Omitting this option will lead to an interactive password
prompt.
-m <memory> Maximum amount of megabytes in RAM which may be consumed
for buffering a decrypted file. Decrypting files larger
than this limit needs a temporary file. Default is 512.
-t <temp file> Path to a file which may be (over)written with arbitrary
temporary data. It may become as big as the largest
decrypted file. Omitting this option will ask the OS for
a temporary file, which might not fit enough data if your
decrypted files weigh multiple GB, leading to IO errors.
-v Enable verbose output. Prints every successfully
decrypted file and every non-HBS file to stdout, while
errors are still printed to stderr. Only effective
when not reading from stdin.
When providing files and/or directories as arguments, these files will be
decrypted in-place. Caution! That means that their contents will be
overwritten, but their file attributes are preserved.
If no files or directories are provided, the program expects an encrypted file
on stdin and writes the decrypted file to stdout.