No, the law does allow it with a warrant. It is just like the trunk of your car. Not 'plain sight', and you can deny access. But with a warrant, the cop can force you to hand over the key, or can do whatever damage necessary to break in (at your expense for the damage to property).
There is PLENTY of case law for forensic forays into electronic gear with a warrant.
A warrant requires probable cause. This would require evidence. Again, if its in your mind (like a password) you cannot be compelled by law to divulge.
For the privilege to apply, however, the government must try to compel a person to make a “testimonial” statement that would tend to incriminate him or her. When a person has a valid privilege against self-incrimination, nobody — not even a judge — can force the witness to give that information to the government.
And as we all know, fingerprints do not fall under 5th amendment protection.