FREE ESSAY ON ENCRYPTION

ENCRYPTION

PGP stands for Pretty Good Privacy. It is an encryption program. What encryption does is
hide information from people who do not know the secret word to reveal the information.
Louis J. Freeh, the Director of the Federal Bureau of Investigation, says the honest have
nothing to hide, and only criminals would use encryption. The honest, goes the
implication, have no need of encryption. Let us think about that, for just a minute. The
honest have no need of encryption: they can live completely open lives, and this is
desirable. Their virtue is their defense. This is an attractive argument, but let us see
where it takes us. By this same reasoning, the honest have no need of shades on their
windows. The honest have no need for bathroom doors -- or front doors, for that matter.
The honest have no need to seal the envelopes into which they put their letters or their
bill payments. The honest have no need to take their credit card receipts -- complete
with account number, expiration date, and signature -- but should just leave them at the
sales counter for whoever needs a piece of scrap paper. The honest have no need to look
at anything anyone asks them to sign, but should just sign. The honest should publish
their medical records in their local newspaper. The honest should have their social
security numbers and birth dates on their checks, along with their names and addresses.
The honest should write their PINs on their ATM cards. I think we can imagine a world
where being honest as in these examples would be, shall we say, differently clued. I also
think that world could easily look a lot like the one in which we live. Virtue is a
defense, and a good one. But virtue is a defense against false accusation -- not
victimization. One would think the FBI could tell the difference. That I use encryption
does not mean I am a criminal. It means I recognize that there are people about who are,
or could be tempted into being, less than perfectly honorable. This recognition has a
name. It is called prudence. It is a virtue. What I find truly amusing, though, is that
while the FBI argues that I must be a criminal if I use encryption, the Privacy Act of
1974 requires that I use it if I interact with the government. The Privacy Act of 1974
imposes the legislative requirement on all government agencies to: establish appropriate
administrative, technical, and physical safeguards to insure the security and
confidentiality of records and to protect against any anticipated threats or hazards to
their security or integrity which could result in substantial harm, embarrassment,
inconvenience, or unfairness to any individual on whom information is maintained. The
Federal agencies, of course, in turn impose this requirement on their vendors. For
example, the Health Care Financing Administration, through its rule making body, requires
all health care organizations accepting Federal funds (including Medicare, Medicaid, and
Children's Health Insurance Program) to use, at a minimum, 112 bit symmetric key
encryption and 512 bit asymmetric key encryption. The FBI says only a pedophile or
terrorist would use encryption of this strength. When information is confidential, using
encryption is not furtive: it is responsible. We do not normally confuse prudent and
criminal, or responsible and furtive. That the Clinton administration consistently cannot
tell the difference between these when it comes to encryption is curious. That the
Clinton administration feels the need to convince the rest of us that there is no
difference is absolutely fascinating. The only explanation that springs to mind is that
the Clinton administration has a difficult time distinguishing between public and
private, or imagining that anyone could have a legitimate secret. Given the number of
Clinton administration illegitimate secrets that have been exposed -- certain adult
activities in the Oval Office, and certain failures to notice espionage by foreign powers
that happen to make large campaign contributions, for example -- I suppose I can
understand this point of view. I do not agree with it, however. It may be that the
existence of a pair of underwear may give the Clinton administration an uncontrollable
urge to rummage around in them. I can imagine the sympathy the Clinton administration has
for someone who really wants to rummage around in someone else's shorts, and cannot. But
I believe most people would understand that an urge to rummage around in someone else's
underwear should be suppressed, not made a right under law. Maybe after they outlaw
encryption, they will outlaw belts -- after all, belts block access to people's shorts.
Only someone with something to hide would use a belt. What is wrong with them? Are they
ashamed of what is inside their pants? I do not have to be ashamed of what is inside my
pants to decline to show it to you, thank you very much. It says right here in the
Constitution: The right of the citizen to be free of others rummaging around in his or
her shorts shall not be abridged. Well, actually, it does not say that, but apparently it
should. Perhaps that would be language the Clinton administration could understand. Ah,
but, the argument goes, encryption may prevent the exercise of purient curiosity, but it
also prevents law enforcement from gathering evidence. Well, this is indeed a concern.
None of us wants criminals and scofflaws to have no fear of law enforcement. However,
encryption in fact does not prevent law enforcement from gathering evidence. There has
not been a single case where encryption has prevented law enforcement from obtaining a
conviction. Not one. Zero. Zip. Nada. This is because encryption merely raises the bar on
obtaining information -- it does not prevent it. And it raises the bar only for the
criminal and the curious, not for law enforcement. Encryption does not encumber action of
law: search warrants are not prevented by encryption; subpoenas are not prevented by
encryption; interrogation is not prevented by encryption. Then the argument goes, but
what if there is no evidence other than the encrypted data? As Freeh says in his
testimony before Congress, Police soon may be unable through legal process and with
sufficient probable cause to conduct a reasonable and lawful search or seizure, because
they cannot gain access to evidence being channeled or stored by criminals, terrorists
and spies. Clearly, this is not desirable. But, let us think about this, for just a
second: how could that be? If the only evidence of my criminal activity is encrypted data
on my computer, it must be some awfully strange criminal activity. I cannot have stolen
anything, for example, the Mona Lisa: the Mona Lisa is on a block of wood, and it is
difficult to encrypt a block of wood. I cannot have threatened anyone, say, my sister:
threatening my sister would be rather ineffective if no one knew about it. I cannot have
killed anyone: a body and a weapon cannot be encrypted. I cannot have evaded taxes by
concealing income: the bank has to know about my ill-gotten gains for me to write a check
against them. I cannot even have committed copyright infringement: I need to make illicit
copies of something to do that, and if they are all encrypted their market value is low.
Seriously: what possible crime could there be where the criminal could encrypt all the
evidence? Or even enough evidence to prevent conviction? So, then, why is the Clinton
administration so anti-encryption? It has to be that it just likes rummaging around in
other people's shorts -- or thongs. There really is no other explanation that makes
sense. Encryption does not prevent law enforcement from enforcing the law. What it does
do, however, is keep nosy neighbors' noses out of my business. If there is a legitimate
need to know the information, the neighbor can force the issue in any number of ways:
complain about me to the police, sue me and go through discovery, subpoena my employer,
and so forth. But if it is just purient curiosity, they are out of luck. And I really
feel no need to satisfy someone else's purient curiosity. Wink, wink, nudge, nudge --
what's it like?, as the Monty Python sketch put it. I am just a normal person. I am not
even particularly privacy conscious: I never go around in sunglasses, a trenchcoat with
the collar turned up, and a hat pulled down. I do not have a second identity and a bank
account in Euros. When someone asks me who I am, I tell them: I do not invent a name for
privacy. I am just a person -- a person who uses envelopes for my mail, who takes my
charge card receipts, and who encrypts my data. This is not criminal. This is not even
abnormal. It is just sensible. What PGP DoesPGP, Network Associates' encryption program,
does four types of encryption. These types of encryption are useful in different ways.
Each is discussed below. Conventional EncryptionThe first type of encryption is what most
people think of when they think of encryption. It is called conventional encryption, or
symmetric encryption, or shared secret encryption. In this type of encryption,
information is encrypted with a key, or secret phrase, and is decrypted (recovered) with
the same key. This means that if I want to end you a message, and we agree on using
conventional encryption, we have to meet and agree on the key. If one of us remembers the
key incorrectly, we cannot communicate. If I encrypt the message with the key RED SAIL
and you try to decrypt the message with READ SALE, you will not be able to recover the
message. Key distribution -- getting you the key along with the encrypted message -- is a
real problem with convention encryption. There are several possible ciphers, or
encryption algorithms, that PGP can use. These are CAST, IDEA, and triple DES. (These
names are acronyms for the actual cipher names.) Although cryptographers may prefer one
over the other, they are all sufficient to keep nosy neighbors out of your hair. And none
of them are sufficient to keep governments out of your hair, if you are the type that
attracts the attention of governments. Unless you tell it otherwise, PGP will use CAST.
(Previous version of PGP used IDEA, which is an older cipher than CAST. However, in
cryptography, new does not mean better. Many cryptographers think new means untried. You
can have PGP use IDEA if you are conservative. Like me.) Public Key EncryptionThe second
type of encryption PGP can do is called public key encryption, or asymmetric encryption.
This type of encryption is based on a type of mathematics where the encryption key and
decryption key are different but related. Information is encrypted with the public key
but cannot be decrypted without the related private key. This means that if I want to
send you a message, I get your public key somewhere, encrypt my message, and send it. The
only knowledge the public key gives me is how to encrypt a message so you can read it. It
does not let me recover messages encrypted to that key. Only you -- with your private key
-- can read the message. Now, since the only thing the public key lets you do is send a
message to the owner of the corresponding private key, there is no need to restrict
distribution of the public key. You can give your public key to everyone you know. You
can publish your public key in the newspaper. You can publish your public key on your web
page. Like this: my public keys. PGP's public key encryption actually uses a symmetric
cipher for the actual data. PGP generates a random session key for each encryption, and
encrypts with that. It solves the key distribution problem by encrypting the session key
with the recipient's public key. So only someone who has the recipient's private key can
recover the session key, and, using that, recover the message. As public key encryption
uses conventional encryption, PGP lets you specify which convention cipher to use. There
are also two types of public keys that PGP can used. These are RSA and DH. (These names,
also, are acronyms for the actual public key scheme names.) Although cryptographers may
prefer one over the other, they are both sufficient to keep nosy neighbors out of your
hair. And neither of them are sufficient to keep governments out of your hair, if you are
the type that attracts the attention of governments. The freeware version of PGP will use
DH, and in fact cannot use RSA. (This has to do with patent licensing, not cryptographic
security.) Unless, you get the international freeware version of PGP: that version of PGP
can do RSA. (The patent that needs to be licensed is a US-only patent.) Or unless you
have the 128-bit security add-on for Internet Explorer, either version 4 or version 5:
then PGP can do RSA. (Microsoft licensed the patent, and PGP can use the Internet
Explorer libraries.) Note that current freeware versions of PGP can use RSA keys, as
described above. They cannot, however, create RSA keys. You need an old version of
freeware PGP for that. (For which RSA gave a free license.) Or you need the RSA-capable
commercial version of PGP: that PGP can use RSA keys and generate them. (If you have that
version, you licensed the patent, or rather paid the license fee.) Digital SignaturesThe
third type of encryption PGP can do is a digital signature. This is a variation on public
key encryption that lets others know a message came from you. Remember that keys in
public key encryption came in two related halves: a public key and a private key. The
private key can decrypt messages encrypted with the public key. But the mathematics work
out so that the public key can also decrypt messages encrypted with the private key. Now,
the private key is private -- only the owner has access to it. This means that if you can
decrypt a message with someone's public key, then the message was encrypted with that
person's private key. This means the message came from the person. What is actually
encrypted is a message digest or a message fingerprint, not the actual message. The
message digest is a long binary value derived from the message contents with what is
called a cryptographic hash. What makes a hash cryptographic is that it is impossible to
reverse. That in turn means that you cannot come up with a message to match a specified
hash value. So it is impossible to remove the signature from one message and put it on
another. In this way, digital signatures are actually more secure than physical
signatures: no matter how creative I am with photocopiers or binary editors, I can never
get someone's signature onto a message that they have not, in fact, signed. Encrypted
DisksThe fourth, and last, type of encryption PGP can do is a PGP disk. This is a file on
your computer that acts like another disk drive when it is mounted. But the disk contents
-- all of them, files and free space alike -- are encrypted. When you mount the disk, you
give the pass phrase which decrypts the encryption key which lets PGP access the PGP disk
on behalf of other programs. The other programs do not need to know they are using an
encrypted disk. Without the pass phrase, however, no dice -- the data is locked up tight.
You can access the file containing the encrypted disk, but that will not give you any
information (other than, this is a PGP disk, but you could tell that anyway). Other
TopicsAfter you get used to using PGP, you can enter the world of anonymous remailers and
nyms. These let you be anonymous or pseudonymous. And some day, I will write about them.
But not today. Copyright ? 1999 Brian Hetrick Page last updated 21 June 1999 
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