I want to look at her phone.
Why do you want to look at her phone?
She has her secrets for doing that. The girl is trying to hide something.
If you think she is keeping secrets, you can ask her about it. Invading her privacy is not the way to go.
Fuck her, I want to see what she is hiding.
Everyone deserves their privacy, and not all want their secrets out. How about telling her you notice something odd about her, and maybe she'll tell you?