Here the keys for encryption and decryption differ. There needs to exist a private key, which is only known to the individual, and a public key, which is published. Every person has her or his own private key that is never published. It is used for decrypting only. Mathematically the different keys are linked to each other, still it is nearly impossible to derive the private key from the public one.
For sending a message to someone, one has to look up the other's public key and encrypt the message with it. The keyholder will use his/her private key to decrypt it. While everybody can send a message with the public key, the private key absolutely has to stay secret - and probably will.
"The best system is to use a simple, well understood algorithm which relies on the security of a key rather than the algorithm itself. This means if anybody steals a key, you could just roll another and they have to start all over." (Andrew Carol)
very famous examples for public-key systems are:
· RSA:
The RSA is probably one of the most popular public-key cryptosystems. With the help of RSA, messages can be encrypted, but also digital signatures are provided.
The mathematics behind are supposedly quite easy to understand (see:
· PGP:
PGP is a public key encryption program. Most of all it is used for e-mail encryption.
It is supposed to be quite safe - until now.
· PGPi is simply the international variation of PGP.
for further information about the RSA and other key-systems visit the RSA homepage:
or:
All of those tools, like hash functions, too, can help to enhance security and prevent crime.
They can theoretically, but sometimes they do not, as the example of the published credit card key of France in March 2000 showed.
For more information see:
Still, cryptography can help privacy.
On the other hand cryptography is only one element to assure safe transport of data. It is especially the persons using it who have to pay attention. A key that is told to others or a lost cryptographic key are the end of secrecy.
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3rd cent. Leiden papyrus: medical information gets enciphered to stop abuses
8th cent. - Abu 'Abd al-Rahman al-Khalil ibn Ahmad ibn 'Amr ibn Tammam al Farahidi al-Zadi al Yahmadi finds the solution for a Greek cryptogram by first of all finding out the plaintext behind the encryption, a method which never got out of date. Afterwards he writes a book on cryptography.
- cipher alphabets for magicians are published
1250 the English monk Roger Bacon writes cipher-descriptions. At that time the art of enciphering was a popular game in monasteries
1379 Gabrieli di Lavinde develops the nomenclature-code for Clement VII (114); a code-system made out of ciphers and codes, which kept being irreplaceable until the 19th century
1392 (probably) the English poet Geoffrey Chaucer writes the book The Equatorie of the Planetis, which contains several passages in ciphers made out of letters, digits and symbols
1412 for the first time ciphers including different substitutions for each letter are developed (in Arabic)
~1467 invention of the "Captain Midnight Decoder Badge", the first polyalphabetic cipher (disk); the inventor, Leon Battista Alberti, also called the father of Western cryptography, uses his disk for enciphering and deciphering at the same time
15th/16th century nearly every state, especially England and France, has people working on en- and deciphering for them
1518 the first printed book on cryptology is written by the German monk Johannes Trithemius. He also changes the form of polyalphabetic cipher from disks into rectangulars
1533 the idea to take a pass-phrase as the key for polyalphabetic cipher is realized by Giovan Batista Belaso
1563 Giovanni Battista Porta suggests to use synonyms and misspellings to irritate cryptoanalysts
1585 Blaise de Vigenère has the idea to use former plaintexts or ciphertexts as new keys; he invents the
1587 Mary, Queen of Scots, is beheaded for the attempt to organize the murder of Queen Elisabeth I., whose agents find out about Mary's plans with the help of decryption
1588 the first book in shorthand is published
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1971 IBM's work on the Lucifer cipher and the work of the NSA lead to the U.S. Data Encryption Standard (=
1976
1977/78 the
1984 Congress passes Comprehensive Crime Control Act
- The Hacker Quarterly is founded
1986 Computer Fraud and Abuse Act is passed in the USA
- Electronic Communications Privacy Act
1987 Chicago prosecutors found Computer Fraud and Abuse Task Force
1988 U.S. Secret Service covertly videotapes a hacker convention
1989 NuPrometheus League distributes Apple Computer software
1990 -
- Charles H. Bennett and Gilles Brassard publish their work on Quantum Cryptography
- Martin Luther King Day Crash strikes AT&T long-distance network nationwide
1991
- one of the first conferences for Computers, Freedom and Privacy takes place in San Francisco
- AT&T phone crash; New York City and various airports get affected
1993 the U.S. government announces to introduce the
1994
- the
1990s work on quantum computer and quantum cryptography
- work on biometrics for authentication (finger prints, the iris, smells, etc.)
1996 France liberates its cryptography law: one now can use cryptography if registered
- OECD issues Cryptography Policy Guidelines; a paper calling for encryption exports-standards and unrestricted access to encryption products
1997 April European Commission issues Electronic Commerce Initiative, in favor of strong encryption
1997 June PGP 5.0 Freeware widely available for non-commercial use
1997 June 56-bit DES code cracked by a network of 14,000 computers
1997 August U.S. judge assesses encryption export regulations as violation of the First Amendment
1998 February foundation of Americans for Computer Privacy, a broad coalition in opposition to the U.S. cryptography policy
1998 March
1998 April NSA issues a report about the risks of key recovery systems
1998 July
1998 October Finnish government agrees to unrestricted export of strong encryption
1999 January RSA Data Security, establishes worldwide distribution of encryption product outside the USA
- National Institute of Standards and Technologies announces that 56-bit
- 56-bit DES code is cracked in 22 hours and 15 minutes
1999 May 27 United Kingdom speaks out against key recovery
1999 Sept: the USA announce to stop the restriction of cryptography-exports
2000 as the German government wants to elaborate a cryptography-law, different organizations start a campaign against that law
- computer hackers do no longer only visit websites and change little details there but cause breakdowns of entire systems, producing big economic losses
for further information about the history of cryptography see:
for information about hacker's history see:
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1455
Gutenberg's printing press was an innovative aggregation of inventions known for centuries before Gutenberg: the olive oil press, oil-based ink, block-print technology, and movable types allowed the mass production of the movable type used to reproduce a page of text and enormously increased the production rate. During the Middle Ages it took monks at least a year to make a handwritten copy of a book. Gutenberg could print about 300 sheets per day. Because parchment was too costly for mass production - for the production of one copy of a medieval book often a whole flock of sheep was used - it was substituted by cheap paper made from recycled clothing of the massive number of deads caused by the Great Plague.
Within forty-five years, in 1500, ten million copies were available for a few hundred thousand literate people. Because individuals could examine a range of opinions now, the printed Bible - especially after having been translated into German by Martin Luther - and increasing literacy added to the subversion of clerical authorities. The interest in books grew with the rise of vernacular, non-Latin literary texts, beginning with Dante's Divine Comedy, the first literary text written in Italian.
Among others the improvement of the distribution and production of books as well as increased literacy made the development of print mass media possible.
Michael Giesecke (Sinnenwandel Sprachwandel Kulturwandel. Studien zur Vorgeschichte der Informationsgesellschaft, Frankfurt am Main: Suhrkamp, 1992) has shown that due to a division of labor among authors, printers and typesetters Gutenberg's invention increasingly led to a standardization of - written and unwritten - language in form of orthography, grammar and signs. To communicate one's ideas became linked to the use of a code, and reading became a kind of rite of passage, an important step towards independency in a human's life.
With the growing linkage of knowledge to reading and learning, the history of knowledge becomes the history of reading, of reading dependent on chance and circumstance.
For further details see:
Martin Warnke, Text und Technik,
Bruce Jones, Manuscripts, Books, and Maps: The Printing Press and a Changing World,
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Gutenberg's printing press, an innovative aggregation of inventions known for centuries before Gutenberg: the olive oil press, oil-based ink, block-print technology, and movable types, allowed the mass production of the movable type used to reproduce a page of text and increased the production rate enormously. During the Middle Ages monks took at least a year over making a handwriting copy of a book. Gutenberg printed about 300 sheets per day. Because parchment was too costly for mass production - often for the production of one copy of a medieval book a whole flock of sheep was used - it was substituted by cheap paper made from recycled clothing left over from the massive number of dead caused by the Great Plague.
Within forty-five years, in 1500, already ten million copies were available for a few hundred thousand literate. Because individuals could examine a range of opinions now, the printed Bible, especially after having been translated into German by Martin Luther, and increasing literacy added to the subversion of clerical authorities. The interest in books increased with the rise of vernacular, non-Latin literary texts, beginning with Dante's Divine Comedy, the first literary text written in Italian.
Among others, the improvement of the distribution and the production of books and increased literacy made the development of print mass media possible.
Michael Giesecke (Sinnenwandel Sprachwandel Kulturwandel. Studien zur Vorgeschichte der Informationsgesellschaft, Frankfurt am Main: Suhrkamp, 1992) has shown that due to a division of labor among authors, printers and typesetters Gutenberg's invention increasingly led to a standardization of - written and unwritten - language in form of orthography, grammar and signs. To communicate one's ideas became linked to the use of a kind of code, and reading became a kind of rite of passage, in every human's life an important step towards independency.
With the increasing linkage of knowledge to wide reading and learnedness, the history of knowledge becomes the history of readings, of readings dependent on chance and on circumstance.
For further details see:
Martin Warnke, Text und Technik,
Bruce Jones, Manuscripts, Books, and Maps: The Printing Press and a Changing World,