If you are not under arrest the only information you have to provide the police is your name and address if they ask. Police can only search you in a public place without a warrant if they have reasonable suspicion that you have committed a crime OR if you give consent.
If you are stopped by police for a public search, you have the right to ask:
“What is your reason for searching me?”
And to state
“I do not consent to this search.”
For more information on your rights in police encounters visit highalert.com.au