Is it legal for my employer to require me to consent to releasing information from my personal computer if used for work?

It is perfectly legal. They are not "breaking into" or hacking your computer or files without your consent, which would be illegal--they are saying that if you wish to work there, you have to agree to allow them to do this. If you do not wish to agree to this, conversely, then do not work there (i.e. either quit or risk that they will fire you). Employers may set terms and conditions on employment, which employees must accept, even if intrusive, if they want the job: for example, employees can specify how you dress (dress codes), whether you can have a second or part-time job in addition to your work with them, who you can date (e.g. non-fraternization policies), what you can do for employment after you leave them (e.g. non-competition and non-solicitation agreements), etc. They can also require you give them access to your personal computer.

Suggestion: buy a second computer, as basic and inexpesive as will do the job (or buy a new top-end computer, and make your current one the second computer). Remove all personal files from the second computer and use it only for work.