Are you already in the US? Have you been practicing/in touch with medical studies since you've graduated? Will you be studying full time for steps or have other responsibilities? How many hours per day can you give to Usmle prep?
The time you'll require to pass both the steps with good scores (these days it's very competitive and just passing is not enough), depends on all the factors I have mentioned above. Realistically speaking, 1 year is very less unless you can give 12+ hours to studies almost everyday and have an excellent foundation of the medical studies.
Then you'll also require to do some observerships/externships in the US. It's pretty much a MUST now to have atleast some USCE and LORs before applying.
Anyway, I believe in 2 years it's possible. You can aim for applying in sept 2017 for 2018 match. That gives you 22 months to clear all the steps: (12 months for step 1, 6 months for step 2 CK, 4 months for step 2 CS prep along with few USCE). You can work hard and easily get high scores during this period. But applying in sept 2016 (11 months) will be a little tight schedule, specially for someone who graduated 4 years ago. Once you get to the core of studies you'll understand what I mean. Good luck!