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19. Appendices

THE CYPHERNOMICON: Cypherpunks FAQ and More, Version 0.666, 1994-09-10, Copyright Timothy C. May. All rights reserved. See the detailed disclaimer. Use short sections under "fair use" provisions, with appropriate credit, but don't put your name on my words.

19.2. SUMMARY: Appendices

19.2.1. Main Points

19.2.2. Connections to Other Sections

19.2.3. Where to Find Additional Information

19.2.4. Miscellaneous Comments

  • This is still under construction
  • Disorganized!!!
  • URLs need to be checked

19.3. Appendix -- Sites, Addresses, URL/Web Sites, Etc.

19.3.1. be sure to get soda address straight!!! [use clones]

  • I received mine from the menus are: /pub/cypherpunks/pgp/pgp26

19.3.2. How to use this section

  • comment on URLs being only a snapshot...
    • use reply to Sherry Mayo here

19.3.3. General Crypto and Cypherpunks Sites

  • sci.crypt archive: anon ftp to

    [Mark Henderson]

  • [has probably been changed to site]
  • ml
  • is-cypherpunk.html...[Vincent Cate, 1994-07-03]
  • misc. article on crypto:
  • has REDOC III, Loki91, SHS and HAVAL (Mark Henderson,, 4-17-94, sci.crypt>
    • Some misc. ftp sites to check:
  • PC Expo disk package to [Arsen Ray Arachelian, 1994-07-05]
    • PC Expo disk
  • /pub/crypto/software/dist/US_or_Canada_only_XXXXXXXX/pcxp o/
  • "The FTP site has a bunch of crypto stuff." [Mark Riordan, 1994-07-08]
    • URL for "Applied Cryptography"-related files
  • ography.html

19.3.4. PGP Information and Sites

    • information on where to find PGP
  • send any mail to this site and receive a list back of PGP sites
    • PGP info:, in /pub/gbe and in /pub/qwerty
  • more PGP: <Michael Paul Johnson,, Colorado Catacombs, 4-894>
  • For non-U.S. sources of PGP: send blank mail to
  • Sherry Mayo, a crypto researcher in Australia, is also making versions available:
  • "PGP2.6ui is available (I hope!) on my experimental WWW server, aim your browser at I am new to this WWW thing so let me know if you have any probs downloading. Available on the server is: PGP2.6ui source for unix machines Executable for the PC version of PGP 2.6ui Executable for MacPGP 2.3" [Sherry Mayo, talk.politics.crypto, 1994-09-06]

19.3.5. Key Servers

  • HELP in the subject line for more information about how to use
      • ' 'help' ' as the subject, to get a list of keyservers [Michael Graff,, 1994-07-04]

19.3.6. Remailer Sites

  • To show active remailers: finger

19.3.7. Mail-to-Usenet gateways:

    • <compiled by Matthew J. Ghio, 4-18-94>

19.3.8. Government Information

  • California Legislative Information
    • "You are invited to browse the new edition of my list of Internet and direct dial sources of California government information at URL: " [Chris Mays,, 1994-07-01]
  • NSA Information
    • Can get on NSA/NCSC/NIST mailing list by sending to:

19.3.9. Clipper Info

    • some good Clipper articles and testimony

19.3.10. Other

    • Vincent Cate
  • Export Laws
    • "EFF Board member and Cygnus Support co-founder John Gilmore has set up a World Wide Web page on cryptography export issues, including information on how to apply for export clearance, exchages with Commerce Dept. on export licensing, legal documents on networking issues in relation to export of technology and crypto, and more. The URL is:" [Stanton McCandlish,, 1994-04-21]
  • Large integer math libraries
    • <Mark Riordan,, 4-8 94, sci.crypt>
    • <Michael Paul Johnson, 4-8-94, sci.crypt>
  • Phrack
    • archived at
  • Bruce Sterling's comments at CFP
  • Bruce Sterling's remarks delivered at the "Computers, Freedom and Privacy IV"
  • conference , Mar. 26 1994 in Chicago, are now online at EFF:
  • 4_sterling.speech
  • 94_sterling.speech
  • gopher:// cfp_94_sterling.speech
  •, 1/Publications/Bruce_Sterling, cfp_94_sterling.speech
    • (source: Stanton McCandlish *, 3-31-94)

19.3.11. Crypto papers

  • pub/papers
    • (quantum, other, Siberry, etc.)

19.3.12. CPSR URL


19.4. Appendix -- Glossary


  • Release Note: I regret that I haven't had time to add many new entries here. There are a lot of specialized terms, and I probably could have doubled the number of entries here.
  • Much more work is needed here. In fact, I debated at one point making the FAQ instead into a kind of "Encycopedia Cypherpunkia," with a mix of short and long articles on each of hundreds of topics. Such an organization would suffer the disadvantages found in nearly all lexicographically-organized works: confusion of the concepts.
  • Many of the these entries were compiled for a long handout at the first Cypherpunks meeting, September, 1992. Errors are obviously present. I'll try to keep correcting them when I can.
  • Schneier's "Applied Cryptography" is of course an excellent place to browse for terms, special uses, etc.

19.4.2. agoric systems -- open, free market systems in which voluntary transactions are central.

19.4.3. Alice and Bob -- crypographic protocols are often made clearer by considering parties A and B, or Alice and Bob, performing some protocol. Eve the eavesdropper, Paul the prover, and Vic the verifier are other common stand-in names.

19.4.4. ANDOS -- all or nothing disclosure of secrets.

19.4.5. anonymous credential -- a credential which asserts some right or privelege or fact without revealing the identity of the holder. This is unlike CA driver's licenses.

19.4.6. assymmetric cipher -- same as public key cryptosystem.

19.4.7. authentication -- the process of verifying an identity or credential, to ensure you are who you said you were.

19.4.8. biometric security -- a type of authentication using fingerprints, retinal scans, palm prints, or other physical/biological signatures of an individual.

19.4.9. bit commitment -- e.g., tossing a coin and then committing to the value without being able to change the outcome. The blob is a cryptographic primitive for this.

19.4.10. BlackNet -- an experimental scheme devised by T. May to underscore the nature of anonymous information markets. "Any and all" secrets can be offered for sale via anonymous mailers and message pools. The experiment was leaked via remailer to the Cypherpunks list (not by May) and thence to several dozen Usenet groups by Detweiler. The authorities are said to be investigating it.

19.4.11. blinding, blinded signatures -- A signature that the signer does not remember having made. A blind signature is always a cooperative protocol and the receiver of the signature provides the signer with the blinding information.

19.4.12. blob -- the crypto equivalent of a locked box. A cryptographic primitive for bit commitment, with the properties that a blobs can represent a 0 or a 1, that others cannot tell be looking whether it's a 0 or a 1, that the creator of the blob can "open" the blob to reveal the contents, and that no blob can be both a 1 and a 0. An example of this is a flipped coin covered by a hand.

19.4.13. BnD -

19.4.14. Capstone -

19.4.15. channel -- the path over which messages are transmitted. Channels may be secure or insecure, and may have eavesdroppers (or enemies, or disrupters, etc.) who alter messages, insert and delete messages, etc. Cryptography is the means by which communications over insecure channels are protected.

19.4.16. chosen plaintext attack -- an attack where the cryptanalyst gets to choose the plaintext to be enciphered, e.g., when possession of an enciphering machine or algorithm is in the possession of the cryptanalyst.

19.4.17. cipher -- a secret form of writing, using substitution or transposition of characters or symbols. (From Arabic "sifr," meaning "nothing.")

19.4.18. ciphertext -- the plaintext after it has been encrypted.

19.4.19. Clipper -- the infamous Clipper chip

19.4.20. code -- a restricted cryptosystem where words or letters of a message are replaced by other words chosen from a codebook.

Not part of modern cryptology, but still useful.

19.4.21. coin flippping -- an important crypto primitive, or protocol, in which the equivalent of flipping a fair coin is possible. Implemented with blobs.

19.4.22. collusion -- wherein several participants cooperate to deduce the identity of a sender or receiver, or to break a cipher. Most cryptosystems are sensitive to some forms of collusion. Much of the work on implementing DC Nets, for example, involves ensuring that colluders cannot isolate message senders and thereby trace origins and destinations of mail.

19.4.23. COMINT -

19.4.24. computationally secure -- where a cipher cannot be broken with available computer resources, but in theory can be broken with enough computer resources. Contrast with unconditionally secure.

19.4.25. countermeasure -- something you do to thwart an attacker

19.4.26. credential -- facts or assertions about some entity. For example, credit ratings, passports, reputations, tax status, insurance records, etc. Under the current system, these credentials are increasingly being cross-linked. Blind signatures may be used to create anonymous credentials.

19.4.27. credential clearinghouse -- banks, credit agencies, insurance companies, police departments, etc., that correlate records and decide the status of records.

19.4.28. cryptanalysis -- methods for attacking and breaking ciphers and related cryptographic systems. Ciphers may be broken, traffic may be analyzed, and passwords may be cracked. Computers are of course essential.

19.4.29. crypto anarchy -- the economic and political system after the deployment of encryption, untraceable e-mail, digital pseudonyms, cryptographic voting, and digital cash. A pun on "crypto," meaning "hidden," and as when Gore Vidal called William F. Buckley a "crypto fascist."

19.4.30. cryptography -- another name for cryptology.

19.4.31. cryptology -- the science and study of writing, sending, receiving, and deciphering secret messages. Includes authentication, digital signatures, the hiding of messages (steganography), cryptanalysis, and several other fields.

19.4.32. cyberspace -- the electronic domain, the Nets, and computergenerated spaces. Some say it is the "consensual reality" described in "Neuromancer." Others say it is the phone system. Others have work to do.

19.4.33. DC protocol, or DC-Net -- the dining cryptographers protocol. DC-Nets use multiple participants communicating with the DC protocol.

19.4.34. DES -- the Data Encryption Standard, proposed in 1977 by the National Bureau of Standards (now NIST), with assistance from the National Security Agency. Based on the "Lucifer" cipher developed by Horst Feistel at IBM, DES is a secret key cryptosystem that cycles 64-bit blocks of data through multiple permutations with a 56-bit key controlling the routing. "Diffusion" and "confusion" are combined to form a cipher that has not yet been cryptanalyzed (see "DES, Security of"). DES is in use for interbank transfers, as a cipher inside of several RSA-based systems, and is available for PCs.

19.4.35. DES, Security of -- many have speculated that the NSA placed a trapdoor (or backdoor) in DES to allow it to read DESencrypted messages. This has not been proved. It is known that the original Lucifer algorithm used a 128-bit key and that this key length was shortened to 64 bits (56 bits plus 8 parity bits), ths making exhaustive search much easier (so far as is known, brute-force search has not been done, though it should be feasible today). Shamir and Bihan have used a technique called "differential cryptanalysis" to reduce the exhaustive search needed for chosen plaintext attacks (but with no import for ordinary DES).

19.4.36. differential cryptanalysis -- the Shamir-Biham technique for cryptanalyzing DES. With a chosen plaintext attack, they've reduced the number of DES keys that must be tried from about 2Л56 to about 2Л47 or less. Note, however, that rarely can an attacker mount a chosen plaintext attack on DES systems.

19.4.37. digital cash, digital money -- Protocols for transferring value, monetary or otherwise, electronically. Digital cash usually refers to systems that are anonymous. Digital money systems can be used to implement any quantity that is conserved, such as points, mass, dollars, etc. There are many variations of digital money systems, ranging from VISA numbers to blinded signed digital coins. A topic too large for a single glossary entry.

19.4.38. digital pseudonym -- basically, a "crypto identity." A way for individuals to set up accounts with various organizations without revealing more information than they wish. Users may have several digital pseudonyms, some used only once, some used over the course of many years. Ideally, the pseudonyms can be linked only at the will of the holder. In the simplest form, a public key can serve as a digital pseudonym and need not be linked to a physical identity.

19.4.39. digital signature -- Analogous to a written signature on a document. A modification to a message that only the signer can make but that everyone can recognize. Can be used legally to contract at a distance.

19.4.40. digital timestamping -- one function of a digital notary public, in which some message (a song, screenplay, lab notebook, contract, etc.) is stamped with a time that cannot (easily) be forged.

19.4.41. dining cryptographers protocol (aka DC protocol, DC nets) -the untraceable message sending system invented by David

Chaum. Named after the "dining philosophers" problem in computer science, participants form circuits and pass messages in such a way that the origin cannot be deduced, barring collusion. At the simplest level, two participants share a key between them. One of them sends some actual message by bitwise exclusive-ORing the message with the key, while the other one just sends the key itself. The actual message from this pair of participants is obtained by XORing the two outputs. However, since nobody but the pair knows the original key, the actual message cannot be traced to either one of the participants.

19.4.42. discrete logarithm problem -- given integers a, n, and x, find some integer m such that aAm mod n = x, if m exists.

Modular exponentiation, the aAm mod n part, is straightforward (and special purpose chips are available), but the inverse problem is believed to be very hard, in general. Thus it is conjectured that modular exponentiation is a one-way function.

19.4.43. DSS, Digital Signature Standard -- the latest NIST (National Institute of Standards and Technology, successor to NBS) standard for digital signatures. Based on the El Gamal

cipher, some consider it weak and poor substitute for RSA- based signature schemes.

19.4.44. eavesdropping, or passive wiretapping -- intercepting messages without detection. Radio waves may be intercepted, phone lines may be tapped, and computers may have RF emissions detected. Even fiber optic lines can be tapped.

19.4.45. Escrowed Encryption Standard (EES) -- current name for the key escrow system known variously as Clipper, Capstone, Skipjack, etc.

19.4.46. factoring -- Some large numbers are difficult to factor. It is conjectured that there are no feasible--i.e."easy," less than exponential in size of number-- factoring methods. It is also an open problem whether RSA may be broken more easily than by factoring the modulus (e.g., the public key might reveal information which simplifies the problem).

Interestingly, though factoring is believed to be "hard", it is not known to be in the class of NP-hard problems. Professor Janek invented a factoring device, but he is believed to be fictional.

19.4.47. HUMINT -

19.4.48. information-theoretic security -- "unbreakable" security, in which no amount of cryptanalysis can break a cipher or system. One time pads are an example (providing the pads are not lost nor stolen nor used more than once, of course). Same as unconditionally secure.

19.4.49. key -- a piece of information needed to encipher or decipher a message. Keys may be stolen, bought, lost, etc., just as with physical keys.

19.4.50. key exchange, or key distribution -- the process of sharing a key with some other party, in the case of symmetric ciphers, or of distributing a public key in an asymmetric cipher. A major issue is that the keys be exchanged reliably and without compromise. Diffie and Hellman devised one such scheme, based on the discrete logarithm problem.

19.4.51. known-plaintext attack -- a cryptanalysis of a cipher where plaintext-ciphertext pairs are known. This attack searches for an unknown key. Contrast with the chosen plaintext attack, where the cryptanalyst can also choose the plaintext to be enciphered.

19.4.52. listening posts -- the NSA and other intelligence agencies maintain sites for the interception of radio, telephone, and satellite communications. And so on. Many sites have been identified (cf. Bamford), and many more sites are suspected.

19.4.53. mail, untraceable -- a system for sending and receiving mail without traceability or observability. Receiving mail anonymously can be done with broadcast of the mail in encrypted form. Only the intended recipient (whose identity, or true name, may be unknown to the sender) may able to decipher the message. Sending mail anonymously apparently requires mixes or use of the dining cryptographers (DC) protocol.

19.4.54. Message Pool

19.4.55. minimum disclosure proofs -- another name for zero knowledge proofs, favored by Chaum.

19.4.56. mixes -- David Chaum's term for a box which performs the function of mixing, or decorrelating, incoming and outgoing electronic mail messages. The box also strips off the outer envelope (i.e., decrypts with its private key) and remails the message to the address on the inner envelope. Tamperresistant modules may be used to prevent cheating and forced disclosure of the mapping between incoming and outgoing mail. A sequence of many remailings effectively makes tracing sending and receiving impossible. Contrast this with the software version, the DC protocol. The "remailers" developed by Cypherpunks are an approximation of a Chaumian mix.

19.4.57. modular exponentiation -- raising an integer to the power of another integer, modulo some integer. For integers a, n, and m, aAm mod n. For example, 5Л3 mod 100 = 25. Modular

exponentiation can be done fairly quickly with a sequence of bit shifts and adds, and special purpose chips have been designed. See also discrete logarithm.

19.4.58. National Security Agency (NSA) -- the largest intelligence agency, responsible for making and breaking ciphers, for intercepting communications, and for ensuring the security of U.S. computers. Headquartered in Fort Meade, Maryland, with many listening posts around the world. The NSA funds cryptographic research and advises other agencies about cryptographic matters. The NSA once obviously had the world's leading cryptologists, but this may no longer be the case.

19.4.59. negative credential -- a credential that you possess that you don't want any one else to know, for example, a bankruptcy filing. A formal version of a negative reputation.

19.4.60. NP-complete -- a large class of difficult problems. "NP" stands for nondeterministic polynomial time, a class of problems thought in general not to have feasible algorithms for their solution. A problem is "complete" if any other

NP problem may be reduced to that problem. Many important combinatorial and algebraic problems are NP-complete: the travelling salesman problem, the Hamiltonian cycle problem, the graph isomorphism problem, the word problem, and on and on.

19.4.61. oblivious transfer -- a cryptographic primitive that involves the probablistic transmission of bits. The sender does not

know if the bits were received.

19.4.62. one-time pad -- a string of randomly-selected bits or symbols which is combined with a plaintext message to produce the ciphertext. This combination may be shifting letters some

amount, bitwise exclusive-ORed, etc.). The recipient, who also has a copy of the one time pad, can easily recover the plaintext. Provided the pad is only used once and then destroyed, and is not available to an eavesdropper, the system is perfectly secure, i.e., it is information- theoretically secure. Key distribution (the pad) is obviously a practical concern, but consider CD-ROM's.

19.4.63. one-way function -- a function which is easy to compute in one direction but hard to find any inverse for, e.g. modular exponentiation, where the inverse problem is known as the discrete logarithm problem. Compare the special case of trap door one-way functions. An example of a one-way operation

is multiplication: it is easy to multiply two prime numbers of 100 digits to produce a 200-digit number, but hard to factor that 200-digit number.

19.4.64. P ?=? NP -- Certainly the most important unsolved problem in complexity theory. If P = NP, then cryptography as we know it today does not exist. If P = NP, all NP problems are "easy."

19.4.65. padding -- sending extra messages to confuse eavesdroppers and to defeat traffic analysis. Also adding random bits to a message to be enciphered.

19.4.66. PGP

19.4.67. plaintext -- also called cleartext, the text that is to be enciphered.

19.4.68. Pool

19.4.69. Pretty Good Privacy (PGP) -- Phillip Zimmerman's implementation of RSA, recently upgraded to version 2.0, with more robust components and several new features. RSA Data Security has threatened PZ so he no longer works on it.

Version 2.0 was written by a consortium of non-U.S. hackers.

19.4.70. prime numbers -- integers with no factors other than themselves and 1. The number of primes is unbounded. About 1% of the 100 decimal digit numbers are prime. Since there are about 10л70 particles in the universe, there are about 10л23...100 digit primes for each and every particle in the


19.4.71. probabalistic encryption -- a scheme by Goldwasser, Micali, and Blum that allows multiple ciphertexts for the same plaintext, i.e., any given plaintext may have many ciphertexts if the ciphering is repeated. This protects

against certain types of known ciphertext attacks on RSA.

19.4.72. proofs of identity -- proving who you are, either your true name, or your digital identity. Generally, possession of the right key is sufficient proof (guard your key!). Some work

has been done on "is-a-person" credentialling agencies, using the so-called Fiat-Shamir protocol...think of this as a way to issue unforgeable digital passports. Physical proof of identity may be done with biometric security methods. Zero knowledge proofs of identity reveal nothing beyond the fact that the identity is as claimed. This has obvious uses for computer access, passwords, etc.

19.4.73. protocol -- a formal procedure for solving some problem. Modern cryptology is mostly about the study of protocols for many problems, such as coin-flipping, bit commitment (blobs), zero knowledge proofs, dining cryptographers, and so on.

19.4.74. public key -- the key distributed publicly to potential message-senders. It may be published in a phonebook-like directory or otherwise sent. A major concern is the validity of this public key to guard against spoofing or impersonation.

19.4.75. public key cryptosystem -- the modern breakthrough in cryptology, designed by Diffie and Hellman, with contributions from several others. Uses trap door one-way functions so that encryption may be done by anyone with access to the "public key" but decryption may be done only by the holder of the "private key." Encompasses public key encryption, digital signatures, digital cash, and many other protocols and applications.

19.4.76. public key encryption -- the use of modern cryptologic methods to provided message security and authentication. The RSA algorithm is the most widely used form of public key encryption, although other systems exist. A public key may be freely published, e.g., in phonebook-like directories, while the corresponding private key is closely guarded.

19.4.77. public key patents -- M.I.T. and Stanford, due to the work of Rivest, Shamir, Adleman, Diffie, Hellman, and Merkle, formed Public Key Partners to license the various public key, digital signature, and RSA patents. These patents, granted in the early 1980s, expire in the between 1998 and 2002. PKP has licensed RSA Data Security Inc., of Redwood City, CA, which handles the sales, etc.

19.4.78. quantum cryptography -- a system based on quantum-mechanical principles. Eavesdroppers alter the quantum state of the system and so are detected. Developed by Brassard and Bennett, only small laboratory demonstrations have been made.

19.4.79. remailers -- software versions of Chaum's "mixes," for the sending of untraceable mail. Various features are needed to do this: randomized order of resending, encryption at each stage (picked in advance by the sender, knowing the chain of remailers), padding of message sizes. The first remailer was written by E. Hughes in perl, and about a dozen or so are active now, with varying feature sets.

19.4.80. reputations -- the trail of positive and negative associations and judgments that some entity accrues. Credit ratings, academic credentials, and trustworthiness are all examples. A digital pseudonym will accrue these reputation credentials based on actions, opinions of others, etc. In crypto anarchy, reputations and agoric systems will be of paramount importance. There are many fascinating issues of how reputation-based systems work, how credentials can be bought and sold, and so forth.

19.4.81. RSA -- the main public key encryption algorithm, developed by Ron Rivest, Adi Shamir, and Kenneth Adleman. It exploits the difficulty of factoring large numbers to create a private key and public key. First invented in 1978, it remains the core of modern public key systems. It is usually much slower than DES, but special-purpose modular exponentiation chips will likely speed it up. A popular scheme for speed is to use RSA to transmit session keys and then a high-speed cipher like DES for the actual message text.

  • Description -- Let p and q be large primes, typically with more than 100 digits. Let n = pq and find some e such that e is relatively prime to (p - 1)(q - 1). The set of numbers p, q, and e is the private key for RSA. The set of numbers n and e forms the public key (recall that knowing n is not sufficient to easily find p and q...the factoring problem). A message M is encrypted by computing MAe mod n. The owner of the private key can decrypt the encrypted message by exploiting number theory results, as follows. An integer d is computed such that ed =1 (mod (p - 1)(q - 1)). Euler proved a theorem that MA(ed) = M mod n and so Мл(ed) mod n = M. This means that in some sense the integers e and d are "inverses" of each other. [If this is unclear, please see one of the many texts and articles on public key encryption.]

19.4.82. secret key cryptosystem -- A system which uses the same key to encrypt and decrypt traffic at each end of a communication link. Also called a symmetric or one-key system. Contrast

with public key cryptosystem.

19.4.83. SIGINT -

19.4.84. smart cards -- a computer chip embedded in credit card. They can hold cash, credentials, cryptographic keys, etc. Usually these are built with some degree of tamper-resistance. Smart cards may perform part of a crypto transaction, or all of it. Performing part of it may mean checking the computations of a more powerful computer, e.g., one in an ATM.

19.4.85. spoofing, or masquerading -- posing as another user. Used for stealing passwords, modifying files, and stealing cash.

Digital signatures and other authentication methods are useful to prevent this. Public keys must be validated and protected to ensure that others don't subsititute their own public keys which users may then unwittingly use.

19.4.86. steganography -- a part of cryptology dealing with hiding messages and obscuring who is sending and receiving messages. Message traffic is often padded to reduce the signals that would otherwise come from a sudden beginning of messages.

"Covered writing."

19.4.87. symmetric cipher -- same as private key cryptosystem.

19.4.88. tamper-responding modules, tamper-resistant modules (TRMs) -sealed boxes or modules which are hard to open, requiring extensive probing and usually leaving ample evidence that the tampering has occurred. Various protective techniques are

used, such as special metal or oxide layers on chips, armored coatings, embedded optical fibers, and other measures to thwart analysis. Popularly called "tamper-proof boxes." Uses include: smart cards, nuclear weapon initiators, cryptographic key holders, ATMs, etc.

19.4.89. tampering, or active wiretapping -- intefering with messages and possibly modifying them. This may compromise data security, help to break ciphers, etc. See also spoofing.

19.4.90. Tessera

19.4.91. token -- some representation, such as ID cards, subway tokens, money, etc., that indicates possession of some property or value.

19.4.92. traffic analysis -- determining who is sending or receiving messages by analyzing packets, frequency of packets, etc. A

part of steganography. Usually handled with traffic padding.

19.4.93. traffic analysis -- identifying characteristics of a message (such as sender, or destination) by watching traffic.

Remailers and encryption help to foil traffic analysys.

19.4.94. transmission rules -- the protocols for determining who can send messages in a DC protocol, and when. These rules are needed to prevent collision and deliberate jamming of the channels.

19.4.95. trap messages -- dummy messages in DC Nets which are used to catch jammers and disrupters. The messages contain no private information and are published in a blob beforehand so that the trap message can later be opened to reveal the disrupter. (There are many strategies to explore here.)

19.4.96. trap-door -- In cryptography, a piece of secret information that allows the holder of a private key to invert a normally hard to invert function.

19.4.97. trap-door one way functions -- functions which are easy to compute in both the forward and reverse direction but for which the disclosure of an algorithm to compute the function in the forward direction does not provide information on how to compute the function in the reverse direction. More simply put, trap-door one way functions are one way for all but the holder of the secret information. The RSA algorithm is the best-known example of such a function.

19.4.98. unconditional security -- same as information-theoretic security, that is, unbreakable except by loss or theft of the key.

19.4.99. unconditionally secure -- where no amount of intercepted ciphertext is enough to allow the cipher to be broken, as with the use of a one-time pad cipher. Contrast with computationally secure.

19.4.100. URLs

19.4.101. voting, cryptographic -- Various schemes have been devised for anonymous, untraceable voting. Voting schemes should have several properties: privacy of the vote, security of the vote (no multiple votes), robustness against disruption by jammers or disrupters, verifiability (voter has confidence in the results), and efficiency.

19.4.102. Whistleblowers

19.4.103. zero knowledge proofs -- proofs in which no knowledge of the actual proof is conveyed. Peggy the Prover demonstrates to Sid the Skeptic that she is indeed in possession of some piece of knowledge without actually revealing any of that knowledge. This is useful for access to computers, because eavesdroppers or dishonest sysops cannot steal the knowledge given. Also called minimum disclosure proofs. Useful for proving possession of some property, or credential, such as age or voting status, without revealing personal information.

19.5. Appendix -- Summary of Crypto Versions

19.5.1. DOS and Windows

  • SecureDevice
  • SecureDrive
  • "Secdrv13d is the latest version. There was an unupdated .exe file in the package that had to be fixed. From the readme file: If you found this file inside FPART13D.ZIP, this is an update and bug fix for the FPART utility of SecureDrive Release 1.3d,
    • Edgar Swank involved?
    • SecureDevice
      • Major Versions:
      • Functions:
      • Principal Authors:
      • Major Platforms:
      • Where to Find:
  • secdrv/secdev.arj See for the ???????
    • Strengths:
    • Weaknesses:
    • Notes:
  • By the way, I'm not the only one who gets SecureDrive and SecureDevice confused. Watch out for this.
    • SFS
  • "A MS-DOS-based package for hard disk encryption. It is implemented as a device driver and encrypts a whole partition (i.e., not a file or a directory). It uses the MDC/SHA cipher. ... It is available from Grabo (, I think), and also from our ftp site: ftp.informatik.uni- I would recommend the Garbo site, because ours is a bit slow." [Vesselin Bontchev,, 1994-09-05]
  • Compared to SecureDrive, users report it to be faster, better-featured, has a Windows interface, is a device driver, and is robust. The disadvantages are that it currently does not ship with source code and uses a more obscure cipher.
  • "SFS (Secure FileSystem) is a set of programs which create and manage a number of encrypted disk volumes, and runs under both DOS and Windows. Each volume appears as a normal DOS drive, but all data stored on it is encryped at the individual-sector level...SFS 1.1 is a maintenance release which fixes a few minor problems in 1.0, and adds a number of features suggested by users. More details on changes are given in in the README file." [Peter Gutmann, sci.crypt, 1994-08-25]
    • "from and all its mirror sites worldwide as /pc/crypt/"
    • WinCrypt.
  • "WinCrypt is pretty good IF you keep your encrypted text to less than the length of your password, AND IF you generate your password randomly, AND IF you only use each password ONCE. :-)" [Michael Paul Johnson, sci.crypt, 1994-07-08]
    • Win PGP
      • there seem to be two identically-named programs:
        • WinPGP, by Christopher w. Geib
        • WinPGP, by Timothy M. Janke and Geoffrey C. Grabow
  • ftp WinPGP 1.0 from - Until this is clarified...
    • PGPShell
  • "PGPShell v3.2 has been released and is available at these sites: (U.S.) (Euro) [still@rintintin.Colorado.EDU (Johannes Kepler), 1994-0707]
    • PGS
  • ftp.informatik.uni-
  • "I just uploaded the bug fix of PGS (v0.99b) on some FTPsites: (Just uploaded it, should be on in a few days) (Just uploaded it, should be on in a few days) [Eelco Cramer, 1994-06-27]
    • DOS disk encryption utilities
      • Several free or nearly free utilities are available:
  • [Vesselin Vladimirov Bontchev, as of 1994-08]
    • Norton's "Diskreet" is weak and essentially useless
  • uses DES in weak (ECB) probably the "snake oil" that Zimmermann writes about in his docs. SFS docs say it is even worse than that.
    • PGS
      • "PGS v0.99c is out there! This new version of PGS supports 8 bytes keyid's. This version will be able to run in a OS/2 DOS box. PGS v0.99c is available on the following site:" [ER CRAMER, 1994-07-08]
    • Program:
      • Major Versions:
      • Functions:
      • Principal Authors:
      • Major Platforms:
      • Where to Find:
      • Strengths:
      • Weaknesses:
      • Notes:

19.5.2. OS/2

19.5.3. Amiga

  • Program: PGPAmiga, Amiga PGP
    • Major Versions: 2.3a.4, PGP 2.6
  • "The Amiga equivalent of PGP 2.6ui is called PGP 2.3a.3" [unknown commenter]
    • Functions:
    • Principal Authors:
    • Major Platforms:
    • Where to Find:
    • Strengths:
    • Weaknesses:
  • Notes: Situation is confusing. 2.3a.3 is not equivalent to PGP 2.6ui.

19.5.4. Unix

  • NeXTStep
  • Sun 4.3
  • Solaris
  • HP
  • SGI
  • swIPe
  • Metzger: It was John Ioannidis' swIPe package, and it was not merely announced but released. Phil has done a similar package for KA9Q and was one of

19.5.5. SFS ?

  • "A MS-DOS-based package for hard disk encryption. It is implemented as a device driver and encrypts a whole partition (i.e., not a file or a directory). It uses the MDC/SHA cipher. ... It is available from Grabo (, I think), and also from our ftp site: ftp.informatik.uni- I would recommend the Garbo site, because ours is a bit slow." [Vesselin Bontchev,, 1994-09-05]

19.5.6. Macintosh

  • more on MacPGP
  • From: phinely@uhunix.uhcc.Hawaii.Edu (Peter Hinely) Subject: Re: MacPGP 2.6ui doesn't actually work Message-ID: CsI3wr.I3B@news.Hawaii.Edu Sender: news@news.Hawaii.Edu Organization: University of Hawaii References: Date: Wed, 6 Jul 1994 04:17:15 GMT Lines: 9 In article (mathew at home) writes: >Well, I downloaded the rumoured MacPGP 2.6ui, but sadly it bombs out >immediately with an address error when I try to run it. MacPGP 2.6ui works on my Quadra 605. The MacBinary process cannot handle pathnames >63 characters, but as long an you encrypt files on the desktop, it's not too much of a problem.
    • From: warlord@MIT.EDU (Derek Atkins) Newsgroups: Subject: Re: When will there be a bug fix for MacPGP? Followup-To: Date: 6 Jul 1994 10:19:13 GMT Organization: Massachusetts Institute of Technology Lines: 19 Message-ID: References: NNTP-Posting-Host: In-reply-to: AWILSON@DRUNIVAC.DREW.EDU's message of 2 Jul 1994 12:25:14 GMT In article AWILSON@DRUNIVAC.DREW.EDU (AL WILSON) writes: When will there be a bug fix for MacPGP (1.1.1)? I am not complaining, I know that the software is free. I just want to start utilizing it for communications at the earliest possible time. There are still a number of outstanding bugs that need to be fixed, but the hope is to make a bugfix release in the near future. I don't know when that is going to be, but hopefully it will be Real Soon Now (TM).
    • Date: Wed, 6 Jul 1994 10:42:08 -0700 From: tcmay (Timothy C. May) To: tcmay Subject: (fwd) Re: What is the difference between 2.6 & 2.6ui? Newsgroups: Organization: NETCOM On-line Communication Services (408 261-4700 guest) Status: O Xref: Path:!netcomsv!decwrl!lll-!!howland.reston.ans.n et!pipex!!iwj10 From: (Ian Jackson) Newsgroups: Subject: Re: What is the difference between 2.6 & 2.6ui? Date: Wed, 6 Jul 1994 10:14:24 GMT Organization: Linux Unlimited Lines: 55 Message-ID: References: NNTP-Posting-Host: Summary: Use 2.6ui :-). Originator: ...BEGIN PGP SIGNED MESSAGE... In article, Stainless Steel Rat wrote:

Ed Dantes writes [quoting normalised - iwj]: >> subject line says it all. > PGP 2.6 is distributed from MIT and is legally available to US and Canadian residents. It uses the RSAREF library. It has code that will prevent >interoperation with earlier versions of PGP. > PGP 2.6ui is a modified version of PGP 2.3a which functions almost identically to MIT PGP 2.6, without the "cripple code" of MIT PGP 2.6. It >is legally available outside the US and Canada only. This is false. PGP 2.6ui is available to US and Canadian residents. It is definitely legal for such people to download PGP 2.6ui and study it. However, RSADSI claim that using PGP 2.6ui in the US and Canada violates their patents on the RSA algorithm and on public key cryptography in general. Other people (like myself) believe that these patents wouldn't stand up if tested in court, and that in any case the damages recoverable would be zero. You might also like to know that the output formats generated by 2.6ui and MIT-2.6 are identical, so that if you choose to use 2.6ui in North America noone will be able to tell the difference anyway. Unfortunately these patent problems have caused many North American FTP sites to stop carrying 2.3a and 2.6ui, for fear of committing contributory infringement. If you would like to examine PGP 2.3a or 2.6ui, they are available on many FTP sites. Try for starters. Look out for the regular postings here in for other sites.

     Version: 2.6
     Ian Jackson, at home <> or

+44 223 575512 Escoerea on IRC. 2 Lexington Close, Cambridge, CB4 3LS, England. Urgent:

This is an export controlled ftp site: read pub/crypt/GETTING_ACCESS for information. ncrypt/ is also export-controlled: read /mpj/README for the characters to replace ???????." [ "W. Kinney" kinney@bogart.Colorado.EDU, 1994-07-08]

  • RIPEM on Macintosh
  • Carl Ellison says "I've only used RIPEM on AOL -- but it should be the same...I run on a Mac, generating the armored file, and then use AOL's "paste from file" option in the File menu to include the encrypted file in the body of my message...In the other direction, I have to use Select All and Copy to get it out of AOL mail, Paste to get it into an editor. From there I can file it and give that file to PGP or RIPEM...BBEDIT on the Mac has good support for RIPEM. I wish I knew how to write BBEDIT extensions for Mac PGP as well." [C.E., 1994-0706]
    • URL for Stego (Macintosh)

19.5.7. Newton

19.5.8. Atari

19.5.9. VMS

19.5.10. IBM VM/etc.

19.5.11. Miscellaneous

19.5.12. File-splitting utilities

  • Several exist.
    • XSPLIT
    • cryptosplit, Ray Cromwell
    • shade

19.6. Appendix -- References

19.6.1. the importance of libraries

  • "Use a library. That's a place with lots of paper periodicals and paper books. Library materials not online, mostly, but it is still where most of the world's encoded knowledge is stored. If you don't like paper, tough. That's the way the world is right now." [Eric Hughes, 199404-07]

19.6.2. Books

  • Bamford, James, "The Puzzle Palace," 1982. The seminal reference on the NSA.
  • N. Koblitz, "A course in number theory and cryptography", QA3.G7NO.114. Very technical, with an emphasis on elliptic functions.
  • D. Welsh, "Codes and Cryptography", Oxford Science Publications, 1988, Eric Hughes especially recommends this.
    • Z103.W461988
    • D.E. Denning, "Cryptography and Data Security", Addison-Wesley, 1982, QA76.9.A25D46. A classic, if a bit dated, introduction by the woman who later became the chief supporter of Clipper.
  • G. Brassard, "Modern Cryptology: a tutorial", Lecture Notes in Computer
  • Science 325, Springer 1988, QA76.L4V.325 A slim little book that's a gem. Sections by David Chaum.
  • Vinge, V., "True Names," 1981. A novel about digital pseudonyms and cyberspace.
  • Card, Orson Scott, "Ender's Game," 1985-6. Novel about kids who adopt digital pseudonyms for political debate.
  • G.J. Simmons,"Contemporary Cryptology", IEEE Press, 1992, QA76.9.A25C6678. A collection of articles by well-known experts. Surprisingly, no discussion of digital money. Gus Simmons designed "Permissive Action Links" for nukes, at Sandia.

19.6.3. sci.crypt

  • archived at and
  • The cryptography anon ftp archive at
    • has been moved to

19.6.4. cryptography-faq

  • in about 10 parts, put out by Crypt Cabal (several Cypherpunks on it)
  •, in /pub/usenet/news.answers/cryptography- faq/part[xx]
  • posted every 21 days to sci.crypt, talk.politics.crypto,
    • sci.answers, news.answers .6.5. RSA FAQ
  • Paul Fahn, RSA Laboratories
  • anonymous FTP to
  •, /pub/usenet/news.answers/cryptography-faq/rsa .6.6. Computers, Freedom and Privacy Conference
  • next Computers, Freedom and Privacy Conference will be March 1995, San Francisco

19.6.7. Various computer security papers, publications, and programs can be found at

  • anonymous ftp to it and look in /pub. /pub/info even has the NSA "Orange Book." (Not a secret, obviously. Anyone can get on the NSA/NCSC's mailing list and get a huge pile of documents sent to them, with new ones arriving every several weeks.)
  • or try /pub/security .6.8. Clipper information by Internet

19.7. Glossary Items

19.7.1. message pools --

19.7.2. pools -- see "message pools."

19.7.3. cover traffic --

19.7.4. padding -- see "message padding

19.7.5. message padding --

19.7.6. latency -

19.7.7. BlackNet -- an experiment in information markets, using anonymous message pools for exchange of instructions and items. Tim May's experiment in guerilla ontology.

19.7.8. ILF -- Information Liberation Front. Distributes copyrighted material via remailers, anonymously. Another experiment in guerilla ontology.

19.7.9. digital mix --

19.7.10. FinCEN -- Financial Crimes Enforcement Network.

19.7.11. true name -- one's actual, physical name. Taken from Vernor Vinge's novel of the same name.

19.7.12. mix --

19.7.13. TEMPEST --

19.7.14. OTP --

19.7.15. Vernam cipher --

19.7.16. detweiler -- verb, to rant and rave about tentacles that are destroying one's sanity through crypto anarchist thought control. Named after L. Detweiler. "He's just detweilering."

19.7.17. remailer -

19.7.18. Stego -

19.7.19. incipits -- message indicators or tags (relates to stego) .7.20. duress code -- a second key which can decrypt a message to something harmless. Could be useful for bank cards, as well as for avoiding incrimination. A form of security through obscurity, and not widely used.

19.8. A comment on software versions, ftp sites, instructions, etc. .8.1. I regret that I can't be complete in all versions, platforms supported, sites for obtaining, instructions, incompatibilities, etc. Frankly, I'm drowning in reports of new versions, questions about use, etc. Most of these versions I have no direct knowledge of, have no experience with, and no appreciation of subtle incompatibilites involved.

19.8.2. There are others who have concentrated on providing up-to- date reports on what is available. Some of them are"

  • site

19.8.3. Reading sci.crypt,, and related groups for a few weeks and looking for programs of interest to one's own situation should give the most recent and current results.

Things are moving quickly, so if one is interested in "AmigaPGP," for example, then the right place to look for the latest versions is in the groups just mentioned, or in groups and ftp sites specific to the Amiga. (Be careful that sabotaged or spoofed versions are not used, as in all crypto. "Joe's AmigaPGP" might need a closer look.)