Someone has a standard (non-compressed) bitcoin private key (256 bits) and wishes to store it on paper. Being paranoid about someone finding the sheet of paper, he/she cuts the private key up and stores the two (or more) equally sized pieces separately. There is no overlap between the different pieces.
Assume a malicious party found one (or more, but not all) of the different chunks. Is the malicious actor able to spend the funds? If so, what steps would be required?
Attempt to answer: My understanding would be, that a malicious actor would have to compute the remaining part of the private key to spend the funds. Though this is easier than 'guessing' the whole key, it should be technically unfeasible after about 100 bits at the time of this writing source. Splitting the key into more chunks would only make guessing more difficult (assuming only one is found), yet easier to recover (assuming all but one are owned). Is there some flaw in my reasoning?
Note: I am aware that multi-sig is the standard way of achieving better security. What I am asking is non-standard.
PS: I'm new to Bitcoin (and to StackExchange as well). Feel free to edit as needed and remove this notice afterwards. Thank you!