[hugh3]

Further, I believe that this strategy would be employed as an argument to not ever giving up the passphrase. You would tell the judge, or whomever, that the phrase is a literal confession of a crime, and thus, by doing so, invoke 5th amendment protection.

I'm not assuming the confession is for a false crime, but nonetheless uttering the phrase "my password is $string' where $string is a true confession is still not a confession.

In your strategy, there are two parts to your confession:

1. The information that your password is the string "$s", and

2. Your volunteering of the information to the judge that the strong $s is in fact a confession of a real crime which you did in fact commit.

Part 1 is not testifying against yourself, unless in conjunction with part 2. Since you voluntarily threw Part 2 into the discussion, you're voluntarily testifying against yourself, and there's no rule against that.

A physical equivalent to your strategy would be to write out a letter of confession, leave it in your basement, and tell the police that the existence of this letter means they're not allowed to search your basement. It's not gonna work.