If the feds come to me with a valid warrant to decrypt my phone -- I'll do it -- rather than risk contempt of court. Their warrant better say what they are looking for.
Anybody else wants to look at it -- they can suck it.
Police & other government agencies have been snooping on suspects' phones for too long, without a warrant, and that is in direct contradiction to this:
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
That is the fourth amendment to the constitution, and it remains the law of this land. No, you cannot search my phone without a warrant.