PGPstands for “Pretty Good Privacy. ” It is an encryption program. Whatencryption does is hide information from people who do not know the “secretword” to reveal the information. Louis J.
Freeh, the Director of theFederal Bureau of Investigation, says the honest have nothing to hide, and onlycriminals would use encryption. The honest, goes the implication, have no needof encryption. Let us think about that, for just a minute. The honest have noneed 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 seewhere it takes us. By this same reasoning, the honest have no need of shades ontheir windows. The honest have no need for bathroom doors — or front doors, forthat matter. The honest have no need to seal the envelopes into which they puttheir letters or their bill payments. The honest have no need to take theircredit card receipts — complete with account number, expiration date, andsignature — but should just leave them at the sales counter for whoever needs apiece of scrap paper.
The honest have no need to look at anything anyone asksthem to sign, but should just sign. The honest should publish their medicalrecords in their local newspaper. The honest should have their social securitynumbers 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 aworld where being “honest” as in these examples would be, shall wesay, “differently clued. ” I also think that world could easily look alot like the one in which we live.
Virtue is a defense, and a good one. Butvirtue is a defense against false accusation — not victimization. One wouldthink the FBI could tell the difference. That I use encryption does not mean Iam a criminal.
It means I recognize that there are people about who are, orcould be tempted into being, less than perfectly honorable. This recognition hasa name. It is called “prudence. ” It is a virtue. What I find trulyamusing, though, is that while the FBI argues that I must be a criminal if I useencryption, the Privacy Act of 1974 requires that I use it if I interact withthe government.
The Privacy Act of 1974 imposes the legislative requirement onall government agencies to: establish appropriate administrative, technical, andphysical safeguards to insure the security and confidentiality of records and toprotect against any anticipated threats or hazards to their security orintegrity which could result in substantial harm, embarrassment, inconvenience,or unfairness to any individual on whom information is maintained. The Federalagencies, of course, in turn impose this requirement on their vendors. Forexample, the Health Care Financing Administration, through its rule making body,requires all health care organizations accepting Federal funds (includingMedicare, Medicaid, and Children’s Health Insurance Program) to use, at aminimum, 112 bit symmetric key encryption and 512 bit asymmetric key encryption. The FBI says only a pedophile or terrorist would use encryption of thisstrength.
When information is confidential, using encryption is not furtive: itis responsible. We do not normally confuse “prudent” and”criminal,” or “responsible” and “furtive. ” Thatthe Clinton administration consistently cannot tell the difference between thesewhen it comes to encryption is curious. That the Clinton administration feelsthe need to convince the rest of us that there is no difference is absolutelyfascinating.
The only explanation that springs to mind is that the Clintonadministration has a difficult time distinguishing between “public”and “private,” or imagining that anyone could have a legitimatesecret. Given the number of Clinton administration illegitimate secrets thathave been exposed — certain adult activities in the Oval Office, and certainfailures to notice espionage by foreign powers that happen to make largecampaign contributions, for example — I suppose I can understand this point ofview. I do not agree with it, however. It may be that the existence of a pair ofunderwear may give the Clinton administration an uncontrollable urge to rummagearound in them. I can imagine the sympathy the Clinton administration has forsomeone 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 insomeone else’s underwear should be suppressed, not made a “right”under law. Maybe after they outlaw encryption, they will outlaw belts — afterall, belts block access to people’s shorts. “Only someone with something tohide would use a belt. What is wrong with them? Are they ashamed of what isinside their pants?” I do not have to be ashamed of what is inside my pantsto decline to show it to you, thank you very much.
It says right here in theConstitution: “The right of the citizen to be free of others rummagingaround in his or her shorts shall not be abridged. ” Well, actually, it doesnot say that, but apparently it should. Perhaps that would be language theClinton administration could understand. Ah, but, the argument goes, encryptionmay prevent the exercise of purient curiosity, but it also prevents lawenforcement from gathering evidence. Well, this is indeed a concern.
None of uswants 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 enforcementfrom obtaining a conviction. Not one. Zero.
Zip. Nada. This is becauseencryption merely raises the bar on obtaining information — it does not preventit. And it raises the bar only for the criminal and the curious, not for lawenforcement. Encryption does not encumber action of law: search warrants are notprevented by encryption; subpoenas are not prevented by encryption;interrogation is not prevented by encryption. Then the argument goes, but whatif there is no evidence other than the encrypted data? As Freeh says in histestimony before Congress, Police soon may be unable through legal process andwith sufficient probable cause to conduct a reasonable and lawful search orseizure, because they cannot gain access to evidence being channeled or storedby criminals, terrorists and spies.
Clearly, this is not desirable. But, let usthink about this, for just a second: how could that be? If the only evidence ofmy criminal activity is encrypted data on my computer, it must be some awfullystrange criminal activity. I cannot have stolen anything, for example, the MonaLisa: the Mona Lisa is on a block of wood, and it is difficult to encrypt ablock of wood. I cannot have threatened anyone, say, my sister: threatening mysister would be rather ineffective if no one knew about it. I cannot have killedanyone: a body and a weapon cannot be encrypted. I cannot have evaded taxes byconcealing income: the bank has to know about my ill-gotten gains for me towrite 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 allencrypted their market value is low. Seriously: what possible crime could therebe where the criminal could encrypt all the evidence? Or even enough evidence toprevent conviction? So, then, why is the Clinton administration soanti-encryption? It has to be that it just likes rummaging around in otherpeople’s shorts — or thongs. There really is no other explanation that makessense. Encryption does not prevent law enforcement from enforcing the law. Whatit does do, however, is keep nosy neighbors’ noses out of my business.
If thereis a legitimate need to know the information, the neighbor can force the issuein any number of ways: complain about me to the police, sue me and go throughdiscovery, subpoena my employer, and so forth. But if it is just purientcuriosity, they are out of luck. And I really feel no need to satisfy someoneelse’s purient curiosity. Wink, wink, nudge, nudge — what’s it like?, as theMonty Python sketch put it. I am just a normal person.
I am not evenparticularly privacy conscious: I never go around in sunglasses, a trenchcoatwith the collar turned up, and a hat pulled down. I do not have a secondidentity and a bank account in Euros. When someone asks me who I am, I tellthem: I do not invent a name for “privacy. ” I am just a person — aperson who uses envelopes for my mail, who takes my charge card receipts, andwho encrypts my data. This is not criminal. This is not even abnormal.
It isjust sensible. What PGP DoesPGP, Network Associates’ encryption program, doesfour types of encryption. These types of encryption are useful in differentways. Each is discussed below. Conventional EncryptionThe first type ofencryption is what most people think of when they think of”encryption.
” It is called conventional encryption, or”symmetric” encryption, or “shared secret” encryption. Inthis type of encryption, information is encrypted with a “key,” orsecret phrase, and is decrypted (recovered) with the same key. This means thatif 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 keyincorrectly, we cannot communicate. If I encrypt the message with the key”RED SAIL” and you try to decrypt the message with “READSALE,” you will not be able to recover the message.
“Keydistribution” — getting you the key along with the encrypted message — isa real problem with convention encryption. There are several possible ciphers,or encryption algorithms, that PGP can use. These are CAST, IDEA, and tripleDES. (These names are acronyms for the actual cipher names. ) Althoughcryptographers may prefer one over the other, they are all sufficient to keepnosy neighbors out of your hair. And none of them are sufficient to keepgovernments out of your hair, if you are the type that attracts the attention ofgovernments.
Unless you tell it otherwise, PGP will use CAST. (Previous versionof 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 areconservative. Like me.
) Public Key EncryptionThe second type of encryption PGPcan do is called public key encryption, or “asymmetric” encryption. This type of encryption is based on a type of mathematics where the encryptionkey and decryption key are different but related. Information is encrypted withthe “public” key but cannot be decrypted without the related”private” key. This means that if I want to send you a message, I getyour public key somewhere, encrypt my message, and send it. The only knowledgethe public key gives me is how to encrypt a message so you can read it. It doesnot let me recover messages encrypted to that key.
Only you — with your privatekey — can read the message. Now, since the only thing the public key lets youdo is send a message to the owner of the corresponding private key, there is noneed to restrict distribution of the public key. You can give your public key toeveryone you know. You can publish your public key in the newspaper. You canpublish your public key on your web page. Like this: my public keys.
PGP’spublic key encryption actually uses a symmetric cipher for the actual data. PGPgenerates a random session key for each encryption, and encrypts with that. Itsolves the key distribution problem by encrypting the session key with therecipient’s public key. So only someone who has the recipient’s private key canrecover the session key, and, using that, recover the message. As public keyencryption uses conventional encryption, PGP lets you specify which conventioncipher to use.
There are also two types of public keys that PGP can used. Theseare RSA and DH. (These names, also, are acronyms for the actual public keyscheme names. ) Although cryptographers may prefer one over the other, they areboth sufficient to keep nosy neighbors out of your hair. And neither of them aresufficient to keep governments out of your hair, if you are the type thatattracts 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, notcryptographic security. ) Unless, you get the “international” freewareversion of PGP: that version of PGP can do RSA. (The patent that needs to belicensed is a US-only patent. ) Or unless you have the 128-bit security add-onfor Internet Explorer, either version 4 or version 5: then PGP can do RSA.
(Microsoft licensed the patent, and PGP can use the Internet Explorerlibraries. ) Note that current freeware versions of PGP can use RSA keys, asdescribed above. They cannot, however, create RSA keys. You need an old versionof freeware PGP for that.
(For which RSA gave a free license. ) Or you need theRSA-capable commercial version of PGP: that PGP can use RSA keys and generatethem. (If you have that version, you licensed the patent, or rather paid thelicense fee. ) Digital SignaturesThe third type of encryption PGP can do is adigital signature. This is a variation on public key encryption that lets othersknow a message came from you.
Remember that keys in public key encryption camein two related halves: a public key and a private key. The private key candecrypt messages encrypted with the public key. But the mathematics work out sothat 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 meansthat if you can decrypt a message with someone’s public key, then the messagewas encrypted with that person’s private key. This means the message came fromthe person. What is actually encrypted is a message digest or a “messagefingerprint,” not the actual message. The message digest is a long binaryvalue derived from the message contents with what is called a cryptographichash. What makes a hash “cryptographic” is that it is impossible toreverse.
That in turn means that you cannot come up with a message to match aspecified hash value. So it is impossible to remove the signature from onemessage and put it on another. In this way, digital signatures are actually moresecure than physical signatures: no matter how creative I am with photocopiersor binary editors, I can never get someone’s signature onto a message that theyhave not, in fact, signed. Encrypted DisksThe fourth, and last, type ofencryption PGP can do is a “PGP disk.
” This is a file on your computerthat acts like another disk drive when it is “mounted. ” But the diskcontents — all of them, files and free space alike — are encrypted. When you”mount” the disk, you give the pass phrase which decrypts theencryption key which lets PGP access the “PGP disk” on behalf of otherprograms. The other programs do not need to know they are using an encrypteddisk.
Without the pass phrase, however, no dice — the data is locked up tight. You can access the file containing the encrypted “disk,” but that willnot give you any information (other than, “this is a PGP disk,” butyou could tell that anyway). Other TopicsAfter you get used to using PGP, youcan enter the world of anonymous remailers and nyms. These let you be anonymousor pseudonymous. And some day, I will write about them.