This article explains what it is, how it works, and practical methods to decrypt and analyze it. A normal, unencrypted UImage header (64 bytes) looks like this:
binwalk -E firmware.bin If the first 1 MB shows high entropy (>0.98) with no known signatures, suspect encryption.
Check for HiLink markers:
If you’ve ever run binwalk on a HiLink firmware update (e.g., from an E3372, B310, or AR series router) and seen only high entropy data with no recognizable UImage magic ( 0x27051956 ), you’ve likely encountered this encrypted header.
hexdump -C firmware.bin | head -n 20 Look for strings like "HUAWEI" , "HiLink" , or "UPDATE" at offset > 0x1000 (they often appear after the encrypted header). Method A – Static key (older devices) Search U-Boot binary (extracted via JTAG or from a decrypted image): encrypted hilink uimage firmware header
with open("firmware.bin", "rb") as f: enc_header = f.read(4096)
If the magic appears, you have the correct key. The rest of the firmware may be encrypted in blocks. Many HiLink images encrypt only the header + first block. The remaining data may be plain or compressed. After decryption, run: This article explains what it is, how it
1. Introduction Huawei’s HiLink protocol powers millions of routers, LTE dongles, and IoT gateways. While standard U-Boot images (UImages) use a well-documented header structure ( struct image_header ), recent HiLink firmware variants employ an encrypted header layer —a deliberate obfuscation to prevent third-party firmware modifications, analysis, and repacking.
cipher = AES.new(key, AES.MODE_CBC, iv) dec_header = cipher.decrypt(enc_header) hexdump -C firmware
Key for E3372 (v1): 0x4A,0x6F,0x6B,0x65,0x72,0x73,0x43,0x6F,0x6D,0x65,0x74,0x21,0x2A,0x2A,0x2A,0x00 Key for B310: Derived from serial number + static seed : Modern HiLink devices (2020+) use device-unique keys, making extraction harder but not impossible via hardware glitching. 3.3 Header Structure After Decryption Once decrypted, the header reverts to a standard UImage header with one twist: the ih_name field often contains a secondary signature or a plaintext marker like "SECURE_HILINK_V1" .
strings u-boot.bin | grep -i "aes" Look for key arrays in rodata section.
