[1009] in cryptography@c2.net mail archive
Re: Undecrypted cyphertext (was: Re: Dorothy and the four
daemon@ATHENA.MIT.EDU (John Young)
Fri Jun 13 14:03:38 1997
Date: Fri, 13 Jun 1997 13:55:25 -0400
To: cryptography@c2.net
From: John Young <jya@pipeline.com>
Carl Ellison wrote in response to Phil Karn's comment on the Federal
Guidelines for Searching and Seizing Computers:
>I remember a discussion with Scott Charney in which he claimed that
>passphrases were protected by the 5th amendment. Then again, he was
>arguing for mandatory Clipper chip use at the time. :)
----------
Excerpts on consent-protected passwords from the
Federal Guidelines for Searching and Seizing Computers,
Department of Justice, 1994 (Scott Charney led the DOJ team).
http://jya.com/doj-search.htm (332K)
These excerpts and others can be found by searching[!] for "password."
***
[page 52]
Although an encrypted computer file has been analogized to a locked
file cabinet (because the owner is attempting to preserve secrecy), it
is also analogous to a document written in a language which is foreign
to the reader. As both of these metaphors demonstrate, the authority
granted by the warrant to search for and seize the encrypted
information also brings the implied authority to decrypt: to "break the
lock" on the cabinet or to "translate" the document. Indeed, a warrant to
seize a car and its contents implicitly authorizes agents to unlock it.
Of course, the rule may be different if the search is based upon consent.
A court might well find that a target who has encrypted his data and has
not disclosed the necessary password has tacitly limited the scope of
his consent. In that case, the better practice is to ask explicitly for
consent to search the encrypted material, as well as for the password.
If the target refuses, agents should obtain a warrant for the encrypted
data.
In United States v. David, 756 F. Supp. 1385 (D. Nev. 1991), the defendant
was cooperating with the government by giving them drug-dealing
information from encrypted files in his computer memo book. During one
interview, the agent learned the defendant's password by standing over
his shoulder and watching as he typed it. Later, when the defendant
stopped cooperating and started destroying information in the notebook,
the agent seized it and used the defendant's password to access the
remaining information. The court reasoned that the agent's learning the
password was like his picking up the key to the container. When the
defendant withdrew his consent to give more information from the memo
book, the act which required a warrant was looking inside the container
--whether locked or unlocked--not the acquisition or even the use of
the key. If the agent did not have authority to search the data, then
knowing the password would not confer it. Id. at 1391. Conversely, if
the agent does have a warrant for the data, she may break the "lock"
to search it. For more comment on the consent issues in the David case,
see the discussion at p. 13 [below].
As a practical matter, getting past the encryption may not be easy, but
there are several approaches to try. First of all, the computer crime
lab or the software manufacturer may be able to assist in decrypting the
file. Investigators should not be discouraged by claims that the
password "can't be broken," as this may simply be untrue. Some can be
done easily with the right software. If that fails, there may be clues
to the password in the other evidence seized--stray notes on hardware
or desks; scribbles in the margins of manuals or on the jackets of disks.
Agents should consider whether the suspect or someone else will provide
the password if requested. In some cases, it might be appropriate to
compel a third party who may know the password (or even the suspect)
to disclose it by subpoena (with limited immunity, if appropriate).
***
[page 13]
1. Scope of the Consent
A person who consents to a search may explicitly limit this consent
to a certain area. United States v. Griffin, 530 F.2d 739, 744
(7th Cir. 1976). When the limits of the consent are clearly
given, either at the time of the search or even afterwards, agents
must respect their bounds. In Vaughn v. Baldwin, 950 F.2d 331 (6th Cir.
1991), the plaintiff dentist had voluntarily turned over records to
the IRS. The IRS agent kept the records for months and refused several
informal requests for their return. Plaintiff then formally, in
writing, revoked his consent to the IRS, which still kept the records
to make copies. Finally, plaintiff sued and the IRS returned the
originals but kept the copies. The court found that the IRS had
violated the Fourth Amendment. Although the IRS was entitled to copy
the records while they lawfully had them, they could not keep the
records once plaintiff revoked his consent. Moreover, considering the
long period of time that the IRS held the documents, the court rejected
the argument that once the plaintiff demanded return of his documents
the government should be entitled to retain them for a reasonable
period for copying.
Consent may also be limited implicitly. In United States v. David,
756 F. Supp. 1385 (D. Nev. 1991), the court held that while the defendant
had consented, pursuant to a cooperation agreement, to share some of
the information contained in his hand-held computer memo book, his
attempt to prevent agents from seeing the file password constituted a
limit on his consent. Although the agent did nothing wrong by leaning
over defendant's shoulder to watch him enter the password, the
government clearly exceeded the implicit limits of David's consent when
agents used the password to read the whole computer book without
David's permission. For a more extensive discussion of encryption issues,
see, infra p. 52.
***
... creating a separate personal directory on a computer may not
sufficiently mark it as exclusive, but protecting that separate
directory with a secret password may "lock the container." In that
event, if law enforcement analysts search the directory by breaking
the password (because the co-user who consented to the search did not
know that password), a court would probably suppress the result.
***
... if parents consent to a search and seizure of floppy disks or
passwords locked in the minor child's room, that consent should be
upheld. The issue becomes more complicated, however, when the sons
and daughters who reside with their parents are adults. In these
situations, courts may reach the opposite result when, as a
practical matter, the adult child has established an exclusive area
in the home that the parents have respected. Id. at 285. See
discussion of United States v. Block, supra p. 14.
***
