Nails or carriage bolts for securing chicken coop to 4x4 posts(legs)?

Basically I am building a 6x3ft(5ft tall) chicken coop and am going to raise it off the ground about 14inches with 4x4 posts that will be used as a leg on each corner.

Should I just secure the 2x4 frame with nails(4 on each face/8 for each corner) or should i use 6 inch carriage bolts?

Nails seem easier but is that enough to hold it?

https://myoutdoorplans.com/animals/large-chicken-coop-plans/?fbclid=IwAR0iaiw1No-4QOLDYGQ966jtGRy_wbNwIC38djOXiJB2LjwfvO5qtZ1tkS0 (basically the design of this floor but with 14" tall 4x4 posts)