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Subject: agsc-tpki-requirements.txt - The Encryption "Business Requirement"
"2) The ability to encrypt web-form content
using public-key
cryptography with public-keys embedded in the form, or that can be found using URIs at encrypt-time. The encrypted transaction must propogate all the way to the end-application as opposed to just the web-server;" This was AFAIK introduced due to anticipated
requirements put by HIPPA, GLBA, etc.
At 50000 ft. it indeed seems quite reasonable to consider
encryption as a general solution to reduce data breaches. But since
TPKI is targeted to also function where "the rubber meets the road", I believe
it is wise to perform some initial feasibility studies before
casting things in stone. Here are my
current findings.
Media Encryption
It is obvious that encryption is a natural solution
for protecting against data theft for backup tapes and for disks in mobile
computers. This type of encryption is already widely deployed, and is
usually transparent for users. Such facilities are also likely to
very soon be a part of the operating systems itself due to the advent of Trusted
Platform Modules (TPMs). In fact, Windows Vista will reportedly
support volume encryption in its very first incarnation.
Selective Data
Encryption
In health care systems there is a whish to make
certain data encrypted so that only the right group of people can make use of
it. This is particularly interesting for research applications where you gather
statistics on patients, but preferably without violating their
privacy. Nevertheless, even when performed in a server environment
(outside of TPKI territory), encryption create issues regarding key management
and much slower operations (like short-circuiting Indexes in databases),
making other options such as "data filtering" an alternative way of dealing with
these requirements.
User-initiated
Encryption
However, making explicit encryption and decryption
by users, a major activity seems less attractive for a number of reasons which I
will try to explain.
Encryption during data capture may not seem
like a problem since you could use the storage server's public
key to encrypt data for secure storage. However, the primary reason for
storing data, is presumably for using it a number of times in the
future. This opens a can of worms. First, hardly
any financial or health data is likely to only be accessed by a single
person. Due to this, there will be a need for multiple keys and
server-based decryption schemes, or distribution of the same secret key to
multiple persons. This breaks the nice and clean picture, as well
as introducing new kinds of vulnerabilities. Secondly, no matter
what security scheme you use, it is in an organizational context unthinkable to
not have a master key (stored in a safe deposit box), which is the 21st century
version of "open sesame".
Personally, I am a firm believer in transparent
security. A PIN-code every now and when is OK, but selecting
encryption keys for carrying out day-to-day tasks seems quite a bit over the
top. Even Doctors are only humans.
Solution
Strong user authentication, transport
encryption using SSL, TPM-hardened operating systems, master keys, and
transparent media encryption should in my opinion sufficiently address the
technical part of current and future data protection regulations and
directives. The rest is "simply" procedures...
The "Super User" - A remaining
problem?
In a paper found on the Internet, the problem
with the super-user was mentioned. It is true that if a server is
compromised and somebody is able to login as "root" (UNIX) or Administrator
(Windows), data could be stolen. TPM-hardened operating systems address
this problem. But even then the super-user
is actually a problem; In spite of the fact that you trust the super-user
for administering accounts, creating backups and installing applications,
you don't not necessarily approve of unrestricted access to sensitive
data. However, it appears that strong authentication using PKI and thus
eliminating the need for "password reset", together with new account
administration modes, requiring user consent or access to the corporate master
key, can enable that fine balance between flexibility and rigidity
that advanced data protection schemes require.
Legislators do
typically not specify technology
Few if any current data protection acts specify
technical solutions[1], but rather the goals of data protection. This is
similar to HSPD-12 (PIV) which does not specify how the identity scheme is
to be engineered, but what it is supposed to accomplish. That NIST, the
technology arm of the US government, forged PIV in PKI,
is because NIST found that PKI was the most suitable technology for the
task. There is though little reason to assume
that legislators will begin to deal with technical
solutions. Somehow, even legislators in all their power and
glory, feel their limits...
My conclusion FWIW, is that there is no apparent reason for adding message encryption to Transaction PKI, and if there is, it is at least lacking a description showing how this would work in real-world applications. From an implementation point of view, message
encryption, severely complicates the design as well.
Anders Rundgren
1) The signature directives are exceptions to
this rule but they are not really about data protection, but about
enabling computer applications to replace critical paper-based
processes.
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