How to decrypt ancast image

[CrazyBoy]

hello everyone,

sorry if this is a stupid question, but what program should i use to decrypt the ancast images (fw.img, c2w.img etc)? i want to do this for reverse engineering purposes.
i already have the keys.
trying with openssl with these commands:
$ openssl enc -d -aes-128-cbc -K keygoeshere -iv ivgoeshere -in image.img -out image-dec-1st.img $ openssl enc -d -aes-128-cbc -K keygoeshere -iv ivgoeshere -in image-dec-1st.img -out image-dec.img
outputs the wrong data.
i believe that the images are double encrypted with the same key.
please tell me if i'm wrong!
thanks.