Huawei S7721u Recovery Image — Verify Failed Repack

First, obtain a legitimate, known-good recovery image for the S7721U (e.g., S7721U_V100R003C01B011_recovery.bin ). Using tools like binwalk , unsquashfs , or Huawei-specific unpackers (e.g., HWFW_tool or unpack_huawei.py ), the image is dissected. On some S7721U variants, the image is also encrypted with AES; here, one must first decrypt using a known key derived from the device's serial number or a global vendor key (often obtainable from leaked SDKs or reverse-engineered bootloaders).