How to determine if the firmware is encrypted

[fredly]

I used binwalk to analyze the zephyr.signed.encrypted.bin file generated by the routine mcuboot_with_encryption. I found that the firmware was not encrypted but merely compressed.The analysis results are as follows.

DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
39012 0x9864 Zlib compressed data, compressed
77680 0x12F70 Zlib compressed data, compressed
93277 0x16C5D Zlib compressed data, best compression
119680 0x1D380 Zlib compressed data, compressed
155108 0x25DE4 Zlib compressed data, compressed
155555 0x25FA3 Zlib compressed data, default compression
179170 0x2BBE2 Zlib compressed data, compressed
211793 0x33B51 Zlib compressed data, best compression

[Turbo J]

The bootloader can't unzip. Thus its not compressed and then encrypted, its encrypted and then compressed.

You have to analyse the decompressed data in order to check whether an image is encrypted.