Posted by Declan McCullagh
December 14, 2007
A federal judge in Vermont has ruled that prosecutors can't force a
criminal defendant accused of having illegal images on his hard drive to
divulge his PGP (Pretty Good Privacy) passphrase.
U.S. Magistrate Judge Jerome Niedermeier ruled that a man charged with
transporting child pornography on his laptop across the Canadian border
has a Fifth Amendment right not to turn over the passphrase to
prosecutors. The Fifth Amendment protects the right to avoid
Niedermeier tossed out a grand jury's subpoena that directed Sebastien
Boucher to provide "any passwords" used with his Alienware laptop.
"Compelling Boucher to enter the password forces him to produce evidence
that could be used to incriminate him," the judge wrote in an order
dated November 29 that went unnoticed until this week. "Producing the
password, as if it were a key to a locked container, forces Boucher to
produce the contents of his laptop."
Especially if this ruling is appealed, U.S. v. Boucher could become a
landmark case. The question of whether a criminal defendant can be
legally compelled to cough up his encryption passphrase remains an
unsettled one, with law review articles for the last decade arguing the
merits of either approach. (A U.S. Justice Department attorney wrote an
article in 1996, for instance, titled "Compelled Production of Plaintext
This debate has been one of analogy and metaphor. Prosecutors tend to
view PGP passphrases as akin to someone possessing a key to a safe
filled with incriminating documents. That person can, in general, be
legally compelled to hand over the key. Other examples include the U.S.
Supreme Court saying that defendants can be forced to provide
fingerprints, blood samples, or voice recordings.
Orin Kerr, a former Justice Department prosecutor who's now a law
professor at George Washington University, shares this view. Kerr
acknowledges that it's a tough call, but says, "I tend to think Judge
Niedermeier was wrong given the specific facts of this case."
The alternate view elevates individual rights over prosecutorial
convenience. It looks to other Supreme Court cases saying Americans
can't be forced to give "compelled testimonial communications" and
argues the Fifth Amendment must apply to encryption passphrases as well.
Courts already have ruled that that such protection extends to the
contents of a defendant's minds, so why shouldn't a passphrase be
shielded as well?
In this case, Judge Niedermeier took the second approach. He said that
encryption keys can be "testimonial," and even the prosecution's
alternative of asking the defendant to type in the passphrase when
nobody was looking would be insufficient.
Laptop files: Unencrypted, then encrypted
A second reason this case is unusual is that Boucher was initially
arrested when customs agents stopped him and searched his laptop when he
and his father crossed the border from Canada on December 17, 2006. An
officer opened the laptop, accessed the files without a password or
passphrase, and allegedly discovered "thousands of images of adult
pornography and animation depicting adult and child pornography."
Boucher was read his Miranda rights, waived them, and allegedly told the
customs agents that he may have downloaded child pornography. But
then--and this is key--the laptop was shut down after Boucher was
arrested. It wasn't until December 26 that a Vermont Department of
Corrections officer tried to access the laptop--prosecutors obtained a
subpoena on December 19--and found that the Z: drive was encrypted with
PGP, or Pretty Good Privacy. (PGP sells software, including whole disk
encryption and drive-specific encryption. It's a little unclear what
exactly happened, but one likely scenario is that Boucher configured PGP
to forget his passphrase, effectively re-encrypting the Z: drive, after
a few hours or days had elapsed.)
According to Niedermeier's written opinion, prosecutors sent Boucher a
grand jury subpoena asking for the passwords because:
Secret Service Agent Matthew Fasvlo, who has experience and training
in computer forensics, testified that it is nearly impossible to
access these encrypted files without knowing the password. There are
no "back doors" or secret entrances to access the files. The only
way to get access without the password is to use an automated system
which repeatedly guesses passwords. According to the government, the
process to unlock drive Z could take years, based on efforts to
unlock similarly encrypted files in another case. Despite its best
efforts, to date the government has been unable to learn the
password to access drive Z.
The opinion added:
If the subpoena is requesting production of the files in drive Z,
the foregone conclusion doctrine does not apply. While the
government has seen some of the files on drive Z, it has not viewed
all or even most of them. While the government may know of the
existence and location of the files it has previously viewed, it
does not know of the existence of other files on drive Z that may
contain incriminating material. By compelling entry of the password
the government would be compelling production of all the files on
drive Z, both known and unknown.
Boucher is a Canadian citizen who is a lawful permanent resident in the
United States and lives with his father in Derry, N.H. Two attorneys
listed as representing him could not immediately be reached for comment
So what happens next? It's possible that prosecutors will be able to
establish that Boucher's laptop has child pornography on it without
being able to access it: after all, there were at least two federal
agents who looked at the laptop when the Z: drive was still unencrypted.
But if this ruling in the case is eventually appealed, it could have a
far-reaching impact in a pro-privacy or pro-law-enforcement direction.
Michael Froomkin, a law professor at the University of Miami, has
written that the government "would have a very hard time" trying to
obtain a memorized passphrase. A similar argument, published in the
University of Chicago Legal Forum in 1996, says:
The courts likely will find that compelling someone to reveal the
steps necessary to decrypt a PGP-encrypted document violates the
Fifth Amendment privilege against compulsory self-incrimination.
Because most users protect their private keys by memorizing
passwords to them and not writing them down, access to encrypted
documents would almost definitely require an individual to disclose
the contents of his mind. This bars the state from compelling its
production. This would force law enforcement officials to grant some
form of immunity to the owners of these documents to gain access to
But prosecutors think they can split the idea of immunity into two
halves: divulging the passphrase, and then using the passphrase to
decrypt the files. A 1996 article by Philip Reitinger of the Department
of Justice's computer crime section proposes a clever device for forcing
a defendant to divulge a PGP passphrase and then convicting him anyway
(remember, the passphrase lets the key be used to decrypt the document):
Finally, even if the foregoing considerations require the government
to grant act-of-production immunity to compel production of a key,
the scope of the immunity should be quite narrow. The contents of
the key are not privileged, and it is the contents that will be used
to decrypt a document. Therefore, the government can use the
contents of the decrypted document without impediment. Unless the
government cannot authenticate the document to be decrypted without
using the act of production of the key, granting act-of-production
immunity should have little effect.
Translation: Giving a defendant limited immunity in terms of forcing
them to turn over the passphrase can lead to a conviction. That's
because the fellow technically isn't being convicted based on his
passphrase; he's being convicted for what it unlocks. Isn't the law
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