- Seamless encryption and decryption of data using asymmetric encryption
- Good compression and decompression rates
- Easily implemented in any programming language (this implementation is written in Golang)
The easiest way to install packd is by using go install:
go install github.com/xerosic/packd/cmd/pcdt@latestYou can also clone the repository and build the binary yourself:
git clone github.com/xerosic/packd.git
cd packd
go build ./cmd/pcdtA .pakd file is essentially made up of boxes of compressed data, each containing their path and the box size (8 bytes).
The data is compressed using zstd, providing good compression and decompression rates within reasonable time.
The first 8 bytes are dedicated to the Packd Identification Entry (aka magic bytes, file signature, etc...), which is <!PAKD!> (3C 21 50 41 4B 44 21 3E in bytes).
A packd file is NOT a valid archive if those bytes are not present at the beginning of the file.
The first header is 8 bytes long and contains general information about the archive. For now only 1 byte is used, which is the encrypted flag.
- 1 byte for the encryption flag. If the flag is 0x00, the data is not encrypted. If the flag is 0x01, the data is encrypted.
The rest of the data is assumed to be empty and is ignored.
The header for each file in the archive (box) is 10 bytes long and has the following characteristics:
- 2 bytes for the path length
- 8 bytes for the box size
The box itself contains the path of the file and the compressed data.
- n bytes for the path
- x bytes for the data
The data is placed after the path so it can be accessed from [header_addr] + path_length.
⚠️ The endianness is to be considered little-endian.
The encryption is done by using an hybrid method of the AES and RSA algorithms.
The AES key is generated randomly and is used to encrypt the data. The AES key is then encrypted using the RSA public key and stored in the archive (to bypass RSA message size limit). The data can be then decrypted using the private key associated with the public key used to encrypt the file.
This method aims to provide a secure way to encrypt and decrypt data without the need to store the password (in case of symmetric encryption) in an edge server (which may not be considered secure).