well institute for diploma in interior designs colleges are given below but i don’t know about whether they provide one year diploma or three years ?so you have to cross check that.

Vogue Institute of Fashion Technology

Gupta College of Management and Technology

JD Institute of Fashion Technology, Bangalore

Inter National Institute of Fashion Design, HSR Layout

Mount Carmel College (MCC Bangalore)

Hope you find it helpful

let me know in the comment box if you are having any further doubts

thanks

Good Luck!