extract keys from and decrypt contents of eOneBook SD cards http://src.kaivo.net/hw/deonebook/
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Jakob Kaivo fba801355b implement decryption 6 months ago
tiny-AES-c@3f69a5899e implement decryption 6 months ago
.gitignore initial commit 6 months ago
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README.md implement decryption 6 months ago
decrypt.c implement decryption 6 months ago
deonebook.c implement decryption 6 months ago
deonebook.h implement decryption 6 months ago
extract.sh implement decryption 6 months ago
genkey.c enforce device type of mmcblk, fail if /sys/block/<device>/device is not a readable directory 6 months ago
getkey.c implement decryption 6 months ago
readkey.c add separate path for reading key from SHM 6 months ago

README.md

DeOneBook

This program is designed to decrypt the contents of eOneBook SD cards. It is able to extract the encryption keys from SD cards to make this automatic with the proper hardware. Without hardware support, decryption is a two-step process, extracting a key using the eOneBook itself, and decryption using that key.

Building

If you have a system with a directly attached SD card reader (i.e. a device that appears as /dev/mmcblk0 or similar, not as /dev/sdb), you can build a native version of the program with:

make

If you do not (this includes all USB readers and some internal devices that are attached through an internal USB adapter), you'll need to cross-compile the tool to run directly on the eOneBook. First install a cross compiler. On Debian and Ubuntu systems, you can do this with:

sudo apt install crossbuild-essential-armhf

Then build with the cross compiler:

make CC=arm-linux-gnueabihf-gcc

Automatic Decryption

If your system has a directly connected SD card reader, you can decrypt files with:

deonebook [-d devicename] <input-file> <output-file>

The default device is mmcblk0. If your SD card reader is something else (n.b. it must be an mmcblk device), specify that via the -d option. Replace with the path to an encrypted file (e.g. /media/sd/001/100E) and with the path to place the newly decrypted file. DeOneBook will determine the encryption key by reading information directly from the SD card.

On-device Key Extraction

If your system does not have a directly connected SD card reader, you can use your eOneBook device to extract the encryption key. You'll need to prep the SD card to execute the program and save its output. First, make sure the SD card is not write-protected by moving the write-protect slider to the end of its slot nearest the pins of the card. Mount the SD card somewhere you can write to it, cd to that mount point, and run the following commands, replacing $DEONEBOOKDIR with the path to the compiled DeOneBook.

Be very careful with these commands, as if you lose or overwrite the original .A001 file, you will not be able to use that SD card in your eOneBook anymore. You are strongly advised to back up the entire SD card before attempting this.

mv .A001 eonebook                   # rename the official firmware
cp $DEONEBOOKDIR/deonebook .        # copy over the key extractor
cp $DEONEBOOKDIR/extract.sh .A001   # copy over the extraction script
chmod +x deonebook .A001            # ensure deonebook files are executable

Put the SD card in your eOneBook and open it up. When the official interface comes up, the key extraction is complete. Close the eOneBook and there will be a file called eonebook.key containing the encryption key for that card.

Manual Decryption

Once you have extraced the key using your eOneBook, you can use that key to manually decrypt that SD card's files. Run:

deonebook -k $KEY <input-file> <output-file>

Replace $KEY with the contents of eonebook.key from the previous step (you could also simply replace it with $(cat eonebook.key)). Replace with the path to an encrypted file, and with the path for the newly decrypted file.