Currently I am having a doubt, while making a "DES PCBC" encryption on an image I observe a bit of the silhouette of the image (Probably because of the XOR between plaintext blocks and ciphertext ones on the algorithm). That happens if I set IV and Key to 0.
However, if I change just the key (key in HEX values), the silhouette disappears. It doesn't happen when I leave the key at 0 and only change the IV.
Currently, I'm a bit lost. Apparently I'm seeing the ciphertext "prevailing" over the plaintext on key change, but I'm seeing plaintext "prevailing" with ciphertext if I don't change the key.
Can someone explain why that happens?
If I leave IV and Key at 0 in PCBC I see a dim image silouette (I am using DES because I'm making a mode analysis). I also see the dim image silhouette if I increase the IV (with the key at 0), but if you increase the key (and keep IV at 0), the silouette is no longer visible.
I want to know if in the XOR and a big key the Ciphertext prevails over plaintext, because in that case I would have solved a problem in my PCBC analysis.