binwalk -Me tpsk706spc822.bin
Look for entropy analysis. High entropy suggests encryption or compression. Low entropy + known magic bytes (e.g., hsqs for squashfs, \x1F\x8B for gzip) indicates modifiable sections.
Before touching a single hex editor, we must understand the anatomy of the keyword.
Typical source devices for this firmware include: tpsk706spc822 firmware repack
Vendors rarely publish complete build instructions, so the tpsk706spc822 bin file you encounter may be encrypted, checksummed, or padded with a vendor-specific header.
Example: Add a custom startup script
cat header_updated.bin uboot_modified.bin new_rootfs.squashfs > tpsk706spc822_mod.bin
For JFFS2:
For UBIFS:
Update kernel image if modified; otherwise reuse the original.
This is the most error-prone step. You must replace the old filesystem chunk in the original tpsk706spc822.bin with your new_rootfs.squashfs while keeping the header, footer, and bootloader intact. binwalk -Me tpsk706spc822
Calculate the byte offsets from the original extraction. For example:
Use dd to concatenate:
dd if=original.bin of=header.bin bs=1 count=512
dd if=kernel.bin of=header+kernel.bin
cat header+kernel.bin new_rootfs.squashfs > repacked_raw.bin