JPAK v2.0 Extended

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Multiuse Javascript Package By: Lucas Teske https://github.com/TeskeVirtualSystem/jpak

#JPAK v2.0 Extended Mode

1.0 Filesystem Specification

The Extended Mode of JPAK is consisted of two new JPAK Format files: a JDS (JPAK Data Storage) and JMS (JPAK Meta Storage). The JPAK Data Storage is consisted about raw (or encrypted/compressed) data described by a JMS file. The struct is as follow:

START	END	Description
0x0	0x4	JDS1 Magic Number
0x4	0xC	Padding (0x00)
0xC	0xY	Start of Files Data

The JPAK Meta Storage is similar to JPAK Filetable Structure, but aditionally has a volume list (JDK) for acessing the data storage. It has the follwing struct:

START	END	Description
0x0	0x4	JMS1 Magic Number
0x4	0xC	Padding (0x00)
0xC	0xU	JSON Volume Table
0xU	0xW	JSON File Table
0xX	0xX+4	uint32_t Producer ID (Look JPAK2.0 spec at 2.1)
0xX+4	0xX+8	uint32_t JPAK Flags (Look JPAK2.0 spec at 2.1)
0xX+8	0xX+12	uint32_t User Flags (Look JPAK2.0 spec at 2.1)
0xX+12	END	uint32_t JSON FileTable Offset

The JSON Filetable is the same, the offset is relative to the first volume. The JSON Volume Table is as follow:

{
    "vol0.jds" :   {
        "filename"  :   "vol0.jds",     //  Volume Filename
    },
    "vol1.jds" :   {
        "filename"  :   "vol1.jds",     //  Volume Filename
    }
}

2.0 File Sharing

The JPAK 2.0 Extended Mode supports file sharing across users keeping the same JPAK Data Storage file. This allows to save space and allows to share it across Cloud Storage accounts. For using the File Sharing mode the full key support must be enabled (Directory Key and File Key set for every file). This allows the owner to selective share only few files/directories with someone. To do so, the owner must decrypt is own file, wipe the keys of directories or files he doesn't want to share (set them to TRUE), and send to the client. The client itself should reencrypt the Meta Storage with his own Master Key and store it on its personal cloud/storage. Then the owner shares the Data Storage with that customer. So when a JPAK Reader reads the extended mode jpak, when it encounters a directory/file with the key set to boolean TRUE it will know its encrypted but it doesnt have the key, so it will give access denied.