I was actually wondering... How long would it take to crack/brute force a 32 bit key/encryption and a 16 bit key/encryptions respectively?
Way too fast. It's only 4,294,967,296 combinations for 32 bit and 65,536 for a 16 bit. I assume it can be cracked in seconds/minutes by a high-grade consumer laptop.
I would also suggest reading the article about breaking mnemonic seed where author had to calculate S
HA-256, SHA-512, RIPEMD-160, EC Addition, EC Multiplication in every iteration and he was able to check ~143,000 mnemonics per second.