Misplaced Pages

#825174

138-886: Until about the 1970s, cryptography was mainly practiced in secret by military or spy agencies. However, that changed when two publications brought it into public awareness: the first publicly available work on public-key cryptography , by Whitfield Diffie and Martin Hellman , and the US government publication of the Data Encryption Standard (DES), a block cipher which became very widely used. The technical roots of Cypherpunk ideas have been traced back to work by cryptographer David Chaum on topics such as anonymous digital cash and pseudonymous reputation systems, described in his paper "Security without Identification: Transaction Systems to Make Big Brother Obsolete" (1985). In

276-473: A chosen-plaintext attack , Eve may choose a plaintext and learn its corresponding ciphertext (perhaps many times); an example is gardening , used by the British during WWII. In a chosen-ciphertext attack , Eve may be able to choose ciphertexts and learn their corresponding plaintexts. Finally in a man-in-the-middle attack Eve gets in between Alice (the sender) and Bob (the recipient), accesses and modifies

414-428: A classical cipher (and some modern ciphers) will reveal statistical information about the plaintext, and that information can often be used to break the cipher. After the discovery of frequency analysis , nearly all such ciphers could be broken by an informed attacker. Such classical ciphers still enjoy popularity today, though mostly as puzzles (see cryptogram ). The Arab mathematician and polymath Al-Kindi wrote

552-501: A shot , contains explosives or other fillings, in use since the 19th century. Artillery shells are ammunition that is designed to be fired from artillery which has an effect over long distances, usually indirectly (i.e., out of sight of the target). There are many different types of artillery ammunition, but they are usually high-explosive and designed to shatter into fragments on impact to maximize damage. The fuze used on an artillery shell can alter how it explodes or behaves so it has

690-638: A book on cryptography entitled Risalah fi Istikhraj al-Mu'amma ( Manuscript for the Deciphering Cryptographic Messages ), which described the first known use of frequency analysis cryptanalysis techniques. Language letter frequencies may offer little help for some extended historical encryption techniques such as homophonic cipher that tend to flatten the frequency distribution. For those ciphers, language letter group (or n-gram) frequencies may provide an attack. Essentially all ciphers remained vulnerable to cryptanalysis using

828-606: A book, Crypto: How the Code Rebels Beat the Government ;– Saving Privacy in the Digital Age , covering the crypto wars of the 1990s in detail. "Code Rebels" in the title is almost synonymous with cypherpunks. The term cypherpunk is mildly ambiguous. In most contexts it means anyone advocating cryptography as a tool for social change, social impact and expression. However, it can also be used to mean

966-438: A committee of talented people. It recommended a gradual relaxation of the existing U.S. government restrictions on encryption. Like many such study reports, its conclusions were largely ignored by policy-makers. Later events such as the final rulings in the cypherpunks lawsuits forced a more complete relaxation of the unconstitutional controls on encryption software. Cypherpunks have filed a number of lawsuits, mostly suits against

1104-404: A corresponding modification has occurred in the method of supplying ammunition in the quantity required. As soon as projectiles were required (such as javelins and arrows), there needed to be a method of replenishment. When non-specialized, interchangeable or recoverable ammunition was used (e.g., arrows), it was possible to pick up spent arrows (both friendly and enemy) and reuse them. However, with

1242-430: A cryptographic hash function is computed, and only the resulting hash is digitally signed. Cryptographic hash functions are functions that take a variable-length input and return a fixed-length output, which can be used in, for example, a digital signature. For a hash function to be secure, it must be difficult to compute two inputs that hash to the same value ( collision resistance ) and to compute an input that hashes to

1380-514: A day from December 1, 1996, to March 1, 1999, and suggests that the number was probably higher earlier. The number of subscribers is estimated to have reached 2,000 in the year 1997. In early 1997, Jim Choate and Igor Chudov set up the Cypherpunks Distributed Remailer, a network of independent mailing list nodes intended to eliminate the single point of failure inherent in a centralized list architecture. At its peak,

1518-412: A different password. Interrogators, having extracted a password, are led to believe that they have indeed unlocked the desired secrets, whereas in reality the actual data is still hidden. In other words, even its presence is hidden. Likewise, cypherpunks have also discussed under what conditions encryption may be used without being noticed by network monitoring systems installed by oppressive regimes. As

SECTION 10

#1732780463826

1656-516: A given output ( preimage resistance ). MD4 is a long-used hash function that is now broken; MD5 , a strengthened variant of MD4, is also widely used but broken in practice. The US National Security Agency developed the Secure Hash Algorithm series of MD5-like hash functions: SHA-0 was a flawed algorithm that the agency withdrew; SHA-1 is widely deployed and more secure than MD5, but cryptanalysts have identified attacks against it;

1794-486: A good cipher to maintain confidentiality under an attack. This fundamental principle was first explicitly stated in 1883 by Auguste Kerckhoffs and is generally called Kerckhoffs's Principle ; alternatively and more bluntly, it was restated by Claude Shannon , the inventor of information theory and the fundamentals of theoretical cryptography, as Shannon's Maxim —'the enemy knows the system'. Different physical devices and aids have been used to assist with ciphers. One of

1932-428: A hashed output that cannot be used to retrieve the original input data. Cryptographic hash functions are used to verify the authenticity of data retrieved from an untrusted source or to add a layer of security. Symmetric-key cryptosystems use the same key for encryption and decryption of a message, although a message or group of messages can have a different key than others. A significant disadvantage of symmetric ciphers

2070-440: A keystream (in place of a Pseudorandom number generator ) and applying an XOR operation to each bit of the plaintext with each bit of the keystream. Message authentication codes (MACs) are much like cryptographic hash functions , except that a secret key can be used to authenticate the hash value upon receipt; this additional complication blocks an attack scheme against bare digest algorithms , and so has been thought worth

2208-409: A modern soldier is an assault rifle , which, like other small arms, uses cartridge ammunition in a size specific to the weapon. Ammunition is carried on the person in box magazines specific to the weapon, ammunition boxes, pouches or bandoliers. The amount of ammunition carried is dependent on the strength of the soldier, the expected action required, and the ability of ammunition to move forward through

2346-422: A more specialized effect. Common types of artillery ammunition include high explosive, smoke, illumination, and practice rounds. Some artillery rounds are designed as cluster munitions . Artillery ammunition will almost always include a projectile (the only exception being demonstration or blank rounds), fuze and propellant of some form. When a cartridge case is not used, there will be some other method of containing

2484-414: A more specific meaning: the replacement of a unit of plaintext (i.e., a meaningful word or phrase) with a code word (for example, "wallaby" replaces "attack at dawn"). A cypher, in contrast, is a scheme for changing or substituting an element below such a level (a letter, a syllable, or a pair of letters, etc.) to produce a cyphertext. Cryptanalysis is the term used for the study of methods for obtaining

2622-759: A participant in the Cypherpunks electronic mailing list described below . The two meanings obviously overlap, but they are by no means synonymous. Documents exemplifying cypherpunk ideas include Timothy C. May's The Crypto Anarchist Manifesto (1992) and The Cyphernomicon (1994), A Cypherpunk's Manifesto . A very basic cypherpunk issue is privacy in communications and data retention . John Gilmore said he wanted "a guarantee -- with physics and mathematics, not with laws -- that we can give ourselves real privacy of personal communications." Such guarantees require strong cryptography , so cypherpunks are fundamentally opposed to government policies attempting to control

2760-530: A range of viewpoints and there was probably no completely unanimous agreement on anything. The general attitude, though, definitely put personal privacy and personal liberty above all other considerations. The list was discussing questions about privacy, government monitoring, corporate control of information, and related issues in the early 1990s that did not become major topics for broader discussion until at least ten years later. Some list participants were highly radical on these issues. Those wishing to understand

2898-458: A reply-to-subscribe system. Approximately two hundred messages a day was typical for the mailing list, divided between personal arguments and attacks, political discussion, technical discussion, and early spam. The cypherpunks mailing list had extensive discussions of the public policy issues related to cryptography and on the politics and philosophy of concepts such as anonymity, pseudonyms, reputation, and privacy. These discussions continue both on

SECTION 20

#1732780463826

3036-476: A secret key is used to process the message (or a hash of the message, or both), and one for verification , in which the matching public key is used with the message to check the validity of the signature. RSA and DSA are two of the most popular digital signature schemes. Digital signatures are central to the operation of public key infrastructures and many network security schemes (e.g., SSL/TLS , many VPNs , etc.). Public-key algorithms are most often based on

3174-520: A security perspective to develop a new standard to "significantly improve the robustness of NIST 's overall hash algorithm toolkit." Thus, a hash function design competition was meant to select a new U.S. national standard, to be called SHA-3 , by 2012. The competition ended on October 2, 2012, when the NIST announced that Keccak would be the new SHA-3 hash algorithm. Unlike block and stream ciphers that are invertible, cryptographic hash functions produce

3312-464: A shared secret key. In practice, asymmetric systems are used to first exchange a secret key, and then secure communication proceeds via a more efficient symmetric system using that key. Examples of asymmetric systems include Diffie–Hellman key exchange , RSA ( Rivest–Shamir–Adleman ), ECC ( Elliptic Curve Cryptography ), and Post-quantum cryptography . Secure symmetric algorithms include the commonly used AES ( Advanced Encryption Standard ) which replaced

3450-519: A significant impact on anti-tank ammunition design, now common in both tank-fired ammunition and in anti-tank missiles, including anti-tank guided missiles . Naval weapons were originally the same as many land-based weapons, but the ammunition was designed for specific use, such as a solid shot designed to hole an enemy ship and chain-shot to cut rigging and sails. Modern naval engagements have occurred over far longer distances than historic battles, so as ship armor has increased in strength and thickness,

3588-401: A specialized effect on a target, such as armor-piercing shells and tracer ammunition , used only in certain circumstances. Ammunition is commonly labeled or colored in a specific manner to assist in its identification and to prevent the wrong ammunition types from being used accidentally or inappropriately. The term ammunition can be traced back to the mid-17th century. The word comes from

3726-406: A story by Edgar Allan Poe . Until modern times, cryptography referred almost exclusively to "encryption", which is the process of converting ordinary information (called plaintext ) into an unintelligible form (called ciphertext ). Decryption is the reverse, in other words, moving from the unintelligible ciphertext back to plaintext. A cipher (or cypher) is a pair of algorithms that carry out

3864-558: A stream cipher. The Data Encryption Standard (DES) and the Advanced Encryption Standard (AES) are block cipher designs that have been designated cryptography standards by the US government (though DES's designation was finally withdrawn after the AES was adopted). Despite its deprecation as an official standard, DES (especially its still-approved and much more secure triple-DES variant) remains quite popular; it

4002-425: A warship is referred to as the "ship's magazine". On a smaller scale, magazine is also the name given to the ammunition storage and feeding device of a repeating firearm. Gunpowder must be stored in a dry place (stable room temperature) to keep it usable, as long as for 10 years. It is also recommended to avoid hot places, because friction or heat might ignite a spark and cause an explosion. The standard weapon of

4140-427: A way to integrate this functionality with the new mailing list software. For a time, the cypherpunks mailing list was a popular tool with mailbombers, who would subscribe a victim to the mailing list in order to cause a deluge of messages to be sent to him or her. (This was usually done as a prank, in contrast to the style of terrorist referred to as a mailbomber.) This precipitated the mailing list sysop(s) to institute

4278-465: A wide variety of cryptanalytic attacks, and they can be classified in any of several ways. A common distinction turns on what Eve (an attacker) knows and what capabilities are available. In a ciphertext-only attack , Eve has access only to the ciphertext (good modern cryptosystems are usually effectively immune to ciphertext-only attacks). In a known-plaintext attack , Eve has access to a ciphertext and its corresponding plaintext (or to many such pairs). In

Cypherpunk - Misplaced Pages Continue

4416-446: A widely used tool in communications, computer networks , and computer security generally. Some modern cryptographic techniques can only keep their keys secret if certain mathematical problems are intractable , such as the integer factorization or the discrete logarithm problems, so there are deep connections with abstract mathematics . There are very few cryptosystems that are proven to be unconditionally secure. The one-time pad

4554-437: Is a list of noteworthy cypherpunks and their achievements: * indicates someone mentioned in the acknowledgements of Stephenson's Cryptonomicon. Cryptography This is an accepted version of this page Cryptography , or cryptology (from Ancient Greek : κρυπτός , romanized :  kryptós "hidden, secret"; and γράφειν graphein , "to write", or -λογία -logia , "study", respectively ),

4692-408: Is activated by the fuze, which causes the ammunition effect (e.g., the exploding of an artillery round). The cartridge is the container that holds the projectile and propellant. Not all ammunition types have a cartridge case. In its place, a wide range of materials can be used to contain the explosives and parts. With some large weapons, the ammunition components are stored separately until loaded into

4830-417: Is also active research examining the relationship between cryptographic problems and quantum physics . Just as the development of digital computers and electronics helped in cryptanalysis, it made possible much more complex ciphers. Furthermore, computers allowed for the encryption of any kind of data representable in any binary format, unlike classical ciphers which only encrypted written language texts; this

4968-497: Is also widely used but broken in practice. The US National Security Agency developed the Secure Hash Algorithm series of MD5-like hash functions: SHA-0 was a flawed algorithm that the agency withdrew; SHA-1 is widely deployed and more secure than MD5, but cryptanalysts have identified attacks against it; the SHA-2 family improves on SHA-1, but is vulnerable to clashes as of 2011; and the US standards authority thought it "prudent" from

5106-408: Is beyond the ability of any adversary. This means it must be shown that no efficient method (as opposed to the time-consuming brute force method) can be found to break the cipher. Since no such proof has been found to date, the one-time-pad remains the only theoretically unbreakable cipher. Although well-implemented one-time-pad encryption cannot be broken, traffic analysis is still possible. There are

5244-443: Is called cryptolinguistics . Cryptolingusitics is especially used in military intelligence applications for deciphering foreign communications. Before the modern era, cryptography focused on message confidentiality (i.e., encryption)—conversion of messages from a comprehensible form into an incomprehensible one and back again at the other end, rendering it unreadable by interceptors or eavesdroppers without secret knowledge (namely

5382-648: Is claimed to have developed the Diffie–Hellman key exchange. Public-key cryptography is also used for implementing digital signature schemes. A digital signature is reminiscent of an ordinary signature; they both have the characteristic of being easy for a user to produce, but difficult for anyone else to forge . Digital signatures can also be permanently tied to the content of the message being signed; they cannot then be 'moved' from one document to another, for any attempt will be detectable. In digital signature schemes, there are two algorithms: one for signing , in which

5520-399: Is combined with the plaintext bit-by-bit or character-by-character, somewhat like the one-time pad . In a stream cipher, the output stream is created based on a hidden internal state that changes as the cipher operates. That internal state is initially set up using the secret key material. RC4 is a widely used stream cipher. Block ciphers can be used as stream ciphers by generating blocks of

5658-560: Is impossible; it is quite unusable in practice. The discrete logarithm problem is the basis for believing some other cryptosystems are secure, and again, there are related, less practical systems that are provably secure relative to the solvability or insolvability discrete log problem. As well as being aware of cryptographic history, cryptographic algorithm and system designers must also sensibly consider probable future developments while working on their designs. For instance, continuous improvements in computer processing power have increased

Cypherpunk - Misplaced Pages Continue

5796-595: Is likely to back down or wise up until it has definitively lost the race." Anonymous remailers such as the Mixmaster Remailer were almost entirely a cypherpunk development. Other cypherpunk-related projects include PGP for email privacy, FreeS/WAN for opportunistic encryption of the whole net, Off-the-record messaging for privacy in Internet chat , and the Tor project for anonymous web surfing. In 1998,

5934-617: Is one, and was proven to be so by Claude Shannon. There are a few important algorithms that have been proven secure under certain assumptions. For example, the infeasibility of factoring extremely large integers is the basis for believing that RSA is secure, and some other systems, but even so, proof of unbreakability is unavailable since the underlying mathematical problem remains open. In practice, these are widely used, and are believed unbreakable in practice by most competent observers. There are systems similar to RSA, such as one by Michael O. Rabin that are provably secure provided factoring n = pq

6072-413: Is packaged with each round of ammunition. In recent years, compressed gas, magnetic energy and electrical energy have been used as propellants. Until the 20th-century, gunpowder was the most common propellant in ammunition. However, it has since been replaced by a wide range of fast-burning compounds that are more reliable and efficient. The propellant charge is distinct from the projectile charge which

6210-710: Is relatively recent, beginning in the mid-1970s. In the early 1970s IBM personnel designed the Data Encryption Standard (DES) algorithm that became the first federal government cryptography standard in the United States. In 1976 Whitfield Diffie and Martin Hellman published the Diffie–Hellman key exchange algorithm. In 1977 the RSA algorithm was published in Martin Gardner 's Scientific American column. Since then, cryptography has become

6348-454: Is the key management necessary to use them securely. Each distinct pair of communicating parties must, ideally, share a different key, and perhaps for each ciphertext exchanged as well. The number of keys required increases as the square of the number of network members, which very quickly requires complex key management schemes to keep them all consistent and secret. In a groundbreaking 1976 paper, Whitfield Diffie and Martin Hellman proposed

6486-626: Is the firearm cartridge , which includes all components required to deliver the weapon effect in a single package. Until the 20th century, black powder was the most common propellant used but has now been replaced in nearly all cases by modern compounds. Ammunition comes in a great range of sizes and types and is often designed to work only in specific weapons systems. However, there are internationally recognized standards for certain ammunition types (e.g., 5.56×45mm NATO ) that enable their use across different weapons and by different users. There are also specific types of ammunition that are designed to have

6624-451: Is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs , missiles , grenades , land mines ) and the component parts of other weapons that create the effect on a target (e.g., bullets and warheads ). The purpose of ammunition is to project a force against a selected target to have an effect (usually, but not always, lethal). An example of ammunition

6762-827: Is the practice and study of techniques for secure communication in the presence of adversarial behavior. More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science , information security , electrical engineering , digital signal processing , physics, and others. Core concepts related to information security ( data confidentiality , data integrity , authentication , and non-repudiation ) are also central to cryptography. Practical applications of cryptography include electronic commerce , chip-based payment cards , digital currencies , computer passwords , and military communications . Cryptography prior to

6900-408: Is the second-largest annual use of lead in the US, accounting for over 60,000 metric tons consumed in 2012. Lead bullets that miss their target or remain in a carcass or body that was never retrieved can enter environmental systems and become toxic to wildlife. The US military has experimented with replacing lead with copper as a slug in their green bullets which reduces the dangers posed by lead in

7038-499: Is theoretically possible to break into a well-designed system, it is infeasible in actual practice to do so. Such schemes, if well designed, are therefore termed "computationally secure". Theoretical advances (e.g., improvements in integer factorization algorithms) and faster computing technology require these designs to be continually reevaluated and, if necessary, adapted. Information-theoretically secure schemes that provably cannot be broken even with unlimited computing power, such as

SECTION 50

#1732780463826

7176-439: Is to find some weakness or insecurity in a cryptographic scheme, thus permitting its subversion or evasion. It is a common misconception that every encryption method can be broken. In connection with his WWII work at Bell Labs , Claude Shannon proved that the one-time pad cipher is unbreakable, provided the key material is truly random , never reused, kept secret from all possible attackers, and of equal or greater length than

7314-434: Is typically the case that use of a quality cipher is very efficient (i.e., fast and requiring few resources, such as memory or CPU capability), while breaking it requires an effort many orders of magnitude larger, and vastly larger than that required for any classical cipher, making cryptanalysis so inefficient and impractical as to be effectively impossible. Symmetric-key cryptography refers to encryption methods in which both

7452-419: Is used across a wide range of applications, from ATM encryption to e-mail privacy and secure remote access . Many other block ciphers have been designed and released, with considerable variation in quality. Many, even some designed by capable practitioners, have been thoroughly broken, such as FEAL . Stream ciphers, in contrast to the 'block' type, create an arbitrarily long stream of key material, which

7590-503: The EFF , also sued over the export restrictions, arguing that preventing publication of cryptographic source code is an unconstitutional restriction on freedom of speech. He won, effectively overturning the export law. See Bernstein v. United States for details. Peter Junger also sued on similar grounds, and won. Cypherpunks encouraged civil disobedience, in particular, US law on the export of cryptography . Until 1997, cryptographic code

7728-533: The Electronic Frontier Foundation , with assistance from the mailing list, built a $ 200,000 machine that could brute-force a Data Encryption Standard key in a few days. The project demonstrated that DES was, without question, insecure and obsolete, in sharp contrast to the US government's recommendation of the algorithm. Cypherpunks also participated, along with other experts, in several reports on cryptographic matters. One such paper

7866-809: The Linux kernel (the actual code has been completely reimplemented several times since then) and today's anonymous remailers . The basic ideas can be found in A Cypherpunk's Manifesto ( Eric Hughes , 1993): "Privacy is necessary for an open society in the electronic age. ... We cannot expect governments, corporations, or other large, faceless organizations to grant us privacy ... We must defend our own privacy if we expect to have any. ... Cypherpunks write code. We know that someone has to write software to defend privacy, and ... we're going to write it." Some are or were senior people at major hi-tech companies and others are well-known researchers (see list with affiliations below). The first mass media discussion of cypherpunks

8004-460: The Manifesto says, "Cypherpunks write code"; the notion that good ideas need to be implemented, not just discussed, is very much part of the culture of the mailing list . John Gilmore , whose site hosted the original cypherpunks mailing list, wrote: "We are literally in a race between our ability to build and deploy technology, and their ability to build and deploy laws and treaties. Neither side

8142-442: The SHA-2 family improves on SHA-1, but is vulnerable to clashes as of 2011; and the US standards authority thought it "prudent" from a security perspective to develop a new standard to "significantly improve the robustness of NIST 's overall hash algorithm toolkit." Thus, a hash function design competition was meant to select a new U.S. national standard, to be called SHA-3 , by 2012. The competition ended on October 2, 2012, when

8280-557: The computational complexity of "hard" problems, often from number theory . For example, the hardness of RSA is related to the integer factorization problem, while Diffie–Hellman and DSA are related to the discrete logarithm problem. The security of elliptic curve cryptography is based on number theoretic problems involving elliptic curves . Because of the difficulty of the underlying problems, most public-key algorithms involve operations such as modular multiplication and exponentiation, which are much more computationally expensive than

8418-495: The detonator of an explosive round or shell. The spelling is different in British English and American English (fuse/fuze respectively) and they are unrelated to a fuse (electrical) . A fuse was earlier used to ignite the propellant (e.g., such as on a firework) until the advent of more reliable systems such as the primer or igniter that is used in most modern ammunition. The fuze of a weapon can be used to alter how

SECTION 60

#1732780463826

8556-508: The one-time pad , are much more difficult to use in practice than the best theoretically breakable but computationally secure schemes. The growth of cryptographic technology has raised a number of legal issues in the Information Age . Cryptography's potential for use as a tool for espionage and sedition has led many governments to classify it as a weapon and to limit or even prohibit its use and export. In some jurisdictions where

8694-583: The propellant bags, usually a breech-loading weapon; see Breechloader . Tank ammunition was developed in WWI as tanks first appeared on the battlefield. However, as tank-on-tank warfare developed (including the development of anti-tank warfare artillery), more specialized forms of ammunition were developed such as high-explosive anti-tank (HEAT) warheads and armour-piercing discarding sabot (APDS), including armour-piercing fin-stabilized discarding sabot (APFSDS) rounds. The development of shaped charges has had

8832-635: The rāz-saharīya which was used to communicate secret messages with other countries. David Kahn notes in The Codebreakers that modern cryptology originated among the Arabs , the first people to systematically document cryptanalytic methods. Al-Khalil (717–786) wrote the Book of Cryptographic Messages , which contains the first use of permutations and combinations to list all possible Arabic words with and without vowels. Ciphertexts produced by

8970-558: The 20th century, and several patented, among them rotor machines —famously including the Enigma machine used by the German government and military from the late 1920s and during World War II . The ciphers implemented by better quality examples of these machine designs brought about a substantial increase in cryptanalytic difficulty after WWI. Cryptanalysis of the new mechanical ciphering devices proved to be both difficult and laborious. In

9108-573: The Carnivore System Technical Review . looked at an FBI scheme for monitoring email. Cypherpunks provided significant input to the 1996 National Research Council report on encryption policy, Cryptography's Role In Securing the Information Society (CRISIS). This report, commissioned by the U.S. Congress in 1993, was developed via extensive hearings across the nation from all interested stakeholders, by

9246-403: The Cypherpunks Distributed Remailer included at least seven nodes. By mid-2005, al-qaeda.net ran the only remaining node. In mid-2013, following a brief outage, the al-qaeda.net node's list software was changed from Majordomo to GNU Mailman , and subsequently the node was renamed to cpunks.org. The CDR architecture is now defunct, though the list administrator stated in 2013 that he was exploring

9384-644: The French la munition , for the material used for war. Ammunition and munition are often used interchangeably, although munition now usually refers to the actual weapons system with the ammunition required to operate it. In some languages other than English ammunition is still referred to as munition, such as: Dutch (" munitie "), French (" munitions "), German (" Munition "), Italian (" munizione ") and Portuguese (" munição "). Ammunition design has evolved throughout history as different weapons have been developed and different effects required. Historically, ammunition

9522-503: The Government Communications Headquarters ( GCHQ ), a British intelligence organization, revealed that cryptographers at GCHQ had anticipated several academic developments. Reportedly, around 1970, James H. Ellis had conceived the principles of asymmetric key cryptography. In 1973, Clifford Cocks invented a solution that was very similar in design rationale to RSA. In 1974, Malcolm J. Williamson

9660-583: The Kautiliyam, the cipher letter substitutions are based on phonetic relations, such as vowels becoming consonants. In the Mulavediya, the cipher alphabet consists of pairing letters and using the reciprocal ones. In Sassanid Persia , there were two secret scripts, according to the Muslim author Ibn al-Nadim : the šāh-dabīrīya (literally "King's script") which was used for official correspondence, and

9798-402: The NIST announced that Keccak would be the new SHA-3 hash algorithm. Unlike block and stream ciphers that are invertible, cryptographic hash functions produce a hashed output that cannot be used to retrieve the original input data. Cryptographic hash functions are used to verify the authenticity of data retrieved from an untrusted source or to add a layer of security. The goal of cryptanalysis

9936-593: The US government alleging that some government action is unconstitutional. Phil Karn sued the State Department in 1994 over cryptography export controls after they ruled that, while the book Applied Cryptography could legally be exported, a floppy disk containing a verbatim copy of code printed in the book was legally a munition and required an export permit, which they refused to grant. Karn also appeared before both House and Senate committees looking at cryptography issues. Daniel J. Bernstein , supported by

10074-660: The United Kingdom, cryptanalytic efforts at Bletchley Park during WWII spurred the development of more efficient means for carrying out repetitive tasks, such as military code breaking (decryption) . This culminated in the development of the Colossus , the world's first fully electronic, digital, programmable computer, which assisted in the decryption of ciphers generated by the German Army's Lorenz SZ40/42 machine. Extensive open academic research into cryptography

10212-630: The advent of explosive or non-recoverable ammunition, this was no longer possible and new supplies of ammunition would be needed. The weight of ammunition required, particularly for artillery shells, can be considerable, causing a need for extra time to replenish supplies. In modern times, there has been an increase in the standardization of many ammunition types between allies (e.g., the NATO Standardization Agreement ) that has allowed for shared ammunition types (e.g., 5.56×45mm NATO). As of 2013, lead-based ammunition production

10350-500: The ammunition has cleared the weapon. The propellant is the component of ammunition that is activated inside the weapon and provides the kinetic energy required to move the projectile from the weapon to the target. Before the use of gunpowder, this energy would have been produced mechanically by the weapons system (e.g., a catapult or crossbow); in modern times, it is usually a form of chemical energy that rapidly burns to create kinetic force, and an appropriate amount of chemical propellant

10488-405: The ammunition to defeat it has also changed. Naval ammunition is now designed to reach very high velocities (to improve its armor-piercing abilities) and may have specialized fuzes to defeat specific types of vessels. However, due to the extended ranges at which modern naval combat may occur, guided missiles have largely supplanted guns and shells. With every successive improvement in military arms,

10626-436: The ammunition works. For example, a common artillery shell fuze can be set to "point detonation" (detonation when it hits a target), delay (detonate after it has hit and penetrated a target), time-delay (explode a specified time after firing or impact) and proximity (explode above or next to a target without hitting it, such as for airburst effects or anti-aircraft shells). These allow a single ammunition type to be altered to suit

10764-474: The amusement of literate observers rather than as a way of concealing information. The Greeks of Classical times are said to have known of ciphers (e.g., the scytale transposition cipher claimed to have been used by the Spartan military). Steganography (i.e., hiding even the existence of a message so as to keep it confidential) was also first developed in ancient times. An early example, from Herodotus ,

10902-453: The combined study of cryptography and cryptanalysis. English is more flexible than several other languages in which "cryptology" (done by cryptologists) is always used in the second sense above. RFC   2828 advises that steganography is sometimes included in cryptology. The study of characteristics of languages that have some application in cryptography or cryptology (e.g. frequency data, letter combinations, universal patterns, etc.)

11040-440: The context of the list might refer to the history of cryptography; in the early 1990s, the US government considered cryptography software a munition for export purposes. ( PGP source code was published as a paper book to bypass these regulations and demonstrate their futility.) In 1992, a deal between NSA and SPA allowed export of cryptography based on 40-bit RC2 and RC4 which was considered relatively weak (and especially after SSL

11178-428: The cryptanalytically uninformed. It was finally explicitly recognized in the 19th century that secrecy of a cipher's algorithm is not a sensible nor practical safeguard of message security; in fact, it was further realized that any adequate cryptographic scheme (including ciphers) should remain secure even if the adversary fully understands the cipher algorithm itself. Security of the key used should alone be sufficient for

11316-616: The damage inflicted by one round. Anti-personnel shells are designed to fragment into many pieces and can affect a large area. Armor-piercing rounds are specially hardened to penetrate armor, while smoke ammunition covers an area with a fog that screens people from view. More generic ammunition (e.g., 5.56×45mm NATO ) can often be altered slightly to give it a more specific effect (e.g., tracer, incendiary), whilst larger explosive rounds can be altered by using different fuzes. The components of ammunition intended for rifles and munitions may be divided into these categories: The term fuze refers to

11454-411: The delivery of explosives. An ammunition dump is a military facility for the storage of live ammunition and explosives that will be distributed and used at a later date. Such a storage facility is extremely hazardous, with the potential for accidents when unloading, packing, and transferring the ammunition. In the event of a fire or explosion, the site and its surrounding area is immediately evacuated and

11592-655: The earliest may have been the scytale of ancient Greece, a rod supposedly used by the Spartans as an aid for a transposition cipher. In medieval times, other aids were invented such as the cipher grille , which was also used for a kind of steganography. With the invention of polyalphabetic ciphers came more sophisticated aids such as Alberti's own cipher disk , Johannes Trithemius ' tabula recta scheme, and Thomas Jefferson 's wheel cypher (not publicly known, and reinvented independently by Bazeries around 1900). Many mechanical encryption/decryption devices were invented early in

11730-612: The early 20th century, cryptography was mainly concerned with linguistic and lexicographic patterns. Since then cryptography has broadened in scope, and now makes extensive use of mathematical subdisciplines, including information theory, computational complexity , statistics, combinatorics , abstract algebra , number theory , and finite mathematics . Cryptography is also a branch of engineering, but an unusual one since it deals with active, intelligent, and malevolent opposition; other kinds of engineering (e.g., civil or chemical engineering) need deal only with neutral natural forces. There

11868-409: The effort. Cryptographic hash functions are a third type of cryptographic algorithm. They take a message of any length as input, and output a short, fixed-length hash , which can be used in (for example) a digital signature. For good hash functions, an attacker cannot find two messages that produce the same hash. MD4 is a long-used hash function that is now broken; MD5 , a strengthened variant of MD4,

12006-549: The encryption and decryption algorithms that correspond to each key. Keys are important both formally and in actual practice, as ciphers without variable keys can be trivially broken with only the knowledge of the cipher used and are therefore useless (or even counter-productive) for most purposes. Historically, ciphers were often used directly for encryption or decryption without additional procedures such as authentication or integrity checks. There are two main types of cryptosystems: symmetric and asymmetric . In symmetric systems,

12144-506: The encryption and the reversing decryption. The detailed operation of a cipher is controlled both by the algorithm and, in each instance, by a "key". The key is a secret (ideally known only to the communicants), usually a string of characters (ideally short so it can be remembered by the user), which is needed to decrypt the ciphertext. In formal mathematical terms, a " cryptosystem " is the ordered list of elements of finite possible plaintexts, finite possible cyphertexts, finite possible keys, and

12282-487: The field since polyalphabetic substitution emerged in the Renaissance". In public-key cryptosystems, the public key may be freely distributed, while its paired private key must remain secret. In a public-key encryption system, the public key is used for encryption, while the private or secret key is used for decryption. While Diffie and Hellman could not find such a system, they showed that public-key cryptography

12420-495: The first list spin-off, coderpunks , were originally hosted on John Gilmore 's toad.com, but after a falling out with the sysop over moderation, the list was migrated to several cross-linked mail-servers in what was called the "distributed mailing list." The coderpunks list, open by invitation only, existed for a time. Coderpunks took up more technical matters and had less discussion of public policy implications. There are several lists today that can trace their lineage directly to

12558-482: The form, an export-restricted item—originally PGP , later a copy of Back's program—would be mailed from a US server to one in Anguilla. In Neal Stephenson 's novel Cryptonomicon many characters are on the "Secret Admirers" mailing list. This is fairly obviously based on the cypherpunks list, and several well-known cypherpunks are mentioned in the acknowledgements. Much of the plot revolves around cypherpunk ideas;

12696-406: The foundations of modern cryptography and provided a mathematical basis for future cryptography. His 1949 paper has been noted as having provided a "solid theoretical basis for cryptography and for cryptanalysis", and as having turned cryptography from an "art to a science". As a result of his contributions and work, he has been described as the "founding father of modern cryptography". Prior to

12834-415: The frequency analysis technique until the development of the polyalphabetic cipher , most clearly by Leon Battista Alberti around the year 1467, though there is some indication that it was already known to Al-Kindi. Alberti's innovation was to use different ciphers (i.e., substitution alphabets) for various parts of a message (perhaps for each successive plaintext letter at the limit). He also invented what

12972-497: The key needed for decryption of that message). Encryption attempted to ensure secrecy in communications, such as those of spies , military leaders, and diplomats. In recent decades, the field has expanded beyond confidentiality concerns to include techniques for message integrity checking, sender/receiver identity authentication, digital signatures , interactive proofs and secure computation , among others. The main classical cipher types are transposition ciphers , which rearrange

13110-478: The late 1980s, these ideas coalesced into something like a movement. In late 1992, Eric Hughes , Timothy C. May , and John Gilmore founded a small group that met monthly at Gilmore's company Cygnus Solutions in the San Francisco Bay Area and was humorously termed cypherpunks by Jude Milhon at one of the first meetings—derived from cipher and cyberpunk . In November 2006, the word

13248-581: The leading characters are building a data haven which will allow anonymous financial transactions, and the book is full of cryptography. But, according to the author the book's title is—in spite of its similarity—not based on the Cyphernomicon, an online cypherpunk FAQ document. Cypherpunk achievements would later also be used on the Canadian e-wallet, the MintChip , and the creation of bitcoin . It

13386-441: The list faded in popularity, so too did it fade in the number of cross-linked subscription nodes. To some extent, the cryptography list acts as a successor to cypherpunks; it has many of the people and continues some of the same discussions. However, it is a moderated list, considerably less zany and somewhat more technical. A number of current systems in use trace to the mailing list, including Pretty Good Privacy , /dev/random in

13524-424: The logistical chain to replenish the supply. A soldier may also carry a smaller amount of specialized ammunition for heavier weapons such as machine guns and mortars, spreading the burden for squad weapons over many people. Too little ammunition poses a threat to the mission, while too much limits the soldier's mobility also being a threat to the mission. A shell is a payload-carrying projectile which, as opposed to

13662-493: The meaning of encrypted information without access to the key normally required to do so; i.e., it is the study of how to "crack" encryption algorithms or their implementations. Some use the terms "cryptography" and "cryptology" interchangeably in English, while others (including US military practice generally) use "cryptography" to refer specifically to the use and practice of cryptographic techniques and "cryptology" to refer to

13800-462: The message. Most ciphers , apart from the one-time pad, can be broken with enough computational effort by brute force attack , but the amount of effort needed may be exponentially dependent on the key size, as compared to the effort needed to make use of the cipher. In such cases, effective security could be achieved if it is proven that the effort required (i.e., "work factor", in Shannon's terms)

13938-417: The modern age was effectively synonymous with encryption , converting readable information ( plaintext ) to unintelligible nonsense text ( ciphertext ), which can only be read by reversing the process ( decryption ). The sender of an encrypted (coded) message shares the decryption (decoding) technique only with the intended recipients to preclude access from adversaries. The cryptography literature often uses

14076-681: The names "Alice" (or "A") for the sender, "Bob" (or "B") for the intended recipient, and "Eve" (or "E") for the eavesdropping adversary. Since the development of rotor cipher machines in World War ;I and the advent of computers in World War II , cryptography methods have become increasingly complex and their applications more varied. Modern cryptography is heavily based on mathematical theory and computer science practice; cryptographic algorithms are designed around computational hardness assumptions , making such algorithms hard to break in actual practice by any adversary. While it

14214-553: The notion of public-key (also, more generally, called asymmetric key ) cryptography in which two different but mathematically related keys are used—a public key and a private key. A public key system is so constructed that calculation of one key (the 'private key') is computationally infeasible from the other (the 'public key'), even though they are necessarily related. Instead, both keys are generated secretly, as an interrelated pair. The historian David Kahn described public-key cryptography as "the most revolutionary new concept in

14352-448: The older DES ( Data Encryption Standard ). Insecure symmetric algorithms include children's language tangling schemes such as Pig Latin or other cant , and all historical cryptographic schemes, however seriously intended, prior to the invention of the one-time pad early in the 20th century. In colloquial use, the term " code " is often used to mean any method of encryption or concealment of meaning. However, in cryptography, code has

14490-432: The only ones known until the 1970s, the same secret key encrypts and decrypts a message. Data manipulation in symmetric systems is significantly faster than in asymmetric systems. Asymmetric systems use a "public key" to encrypt a message and a related "private key" to decrypt it. The advantage of asymmetric systems is that the public key can be freely published, allowing parties to establish secure communication without having

14628-543: The order of letters in a message (e.g., 'hello world' becomes 'ehlol owrdl' in a trivially simple rearrangement scheme), and substitution ciphers , which systematically replace letters or groups of letters with other letters or groups of letters (e.g., 'fly at once' becomes 'gmz bu podf' by replacing each letter with the one following it in the Latin alphabet ). Simple versions of either have never offered much confidentiality from enterprising opponents. An early substitution cipher

14766-414: The original Cypherpunks list: the cryptography list (cryptography@metzdowd.com), the financial cryptography list (fc-announce@ifca.ai), and a small group of closed (invitation-only) lists as well. Toad.com continued to run with the existing subscriber list, those that didn't unsubscribe, and was mirrored on the new distributed mailing list, but messages from the distributed list didn't appear on toad.com. As

14904-442: The possibility of anonymous speech, and publication is vital for an open society and genuine freedom of speech—this is the position of most cypherpunks. In general, cypherpunks opposed the censorship and monitoring from government and police. In particular, the US government's Clipper chip scheme for escrowed encryption of telephone conversations (encryption supposedly secure against most attackers, but breakable by government)

15042-399: The possible keys, to reach a point at which chances are better than even that the key sought will have been found. But this may not be enough assurance; a linear cryptanalysis attack against DES requires 2 known plaintexts (with their corresponding ciphertexts) and approximately 2 DES operations. This is a considerable improvement over brute force attacks. Munition Ammunition

15180-435: The potential threat from enemy forces. A magazine is a place where a quantity of ammunition or other explosive material is stored temporarily prior to being used. The term may be used for a facility where large quantities of ammunition are stored, although this would normally be referred to as an ammunition dump. Magazines are typically located in the field for quick access when engaging the enemy. The ammunition storage area on

15318-487: The remaining node and elsewhere as the list has become increasingly moribund. Events such as the GURPS Cyberpunk raid lent weight to the idea that private individuals needed to take steps to protect their privacy. In its heyday, the list discussed public policy issues related to cryptography, as well as more practical nuts-and-bolts mathematical, computational, technological, and cryptographic matters. The list had

15456-551: The scope of brute-force attacks , so when specifying key lengths , the required key lengths are similarly advancing. The potential impact of quantum computing are already being considered by some cryptographic system designers developing post-quantum cryptography. The announced imminence of small implementations of these machines may be making the need for preemptive caution rather more than merely speculative. Claude Shannon 's two papers, his 1948 paper on information theory , and especially his 1949 paper on cryptography, laid

15594-410: The sender and receiver share the same key (or, less commonly, in which their keys are different, but related in an easily computable way). This was the only kind of encryption publicly known until June 1976. Symmetric key ciphers are implemented as either block ciphers or stream ciphers . A block cipher enciphers input in blocks of plaintext as opposed to individual characters, the input form used by

15732-425: The situation it is required for. There are many designs of a fuze, ranging from simple mechanical to complex radar and barometric systems. Fuzes are usually armed by the acceleration force of firing the projectile, and usually arm several meters after clearing the bore of the weapon. This helps to ensure the ammunition is safer to handle when loading into the weapon and reduces the chance of the detonator firing before

15870-477: The stored ammunition is left to detonate itself completely with limited attempts at firefighting from a safe distance. In large facilities, there may be a flooding system to automatically extinguish a fire or prevent an explosion. Typically, an ammunition dump will have a large buffer zone surrounding it, to avoid casualties in the event of an accident. There will also be perimeter security measures in place to prevent access by unauthorized personnel and to guard against

16008-412: The techniques used in most block ciphers, especially with typical key sizes. As a result, public-key cryptosystems are commonly hybrid cryptosystems , in which a fast high-quality symmetric-key encryption algorithm is used for the message itself, while the relevant symmetric key is sent with the message, but encrypted using a public-key algorithm. Similarly, hybrid signature schemes are often used, in which

16146-508: The traffic and then forward it to the recipient. Also important, often overwhelmingly so, are mistakes (generally in the design or use of one of the protocols involved). Cryptanalysis of symmetric-key ciphers typically involves looking for attacks against the block ciphers or stream ciphers that are more efficient than any attack that could be against a perfect cipher. For example, a simple brute force attack against DES requires one known plaintext and 2 decryptions, trying approximately half of

16284-555: The usage or export of cryptography, which remained an issue throughout the late 1990s. The Cypherpunk Manifesto stated "Cypherpunks deplore regulations on cryptography, for encryption is fundamentally a private act." This was a central issue for many cypherpunks. Most were passionately opposed to various government attempts to limit cryptography— export laws , promotion of limited key length ciphers, and especially escrowed encryption . The questions of anonymity , pseudonymity and reputation were also extensively discussed. Arguably,

16422-433: The use of cryptography in the presence of oppressive authorities. As a result, Cypherpunks have discussed and improved steganographic methods that hide the use of crypto itself, or that allow interrogators to believe that they have forcibly extracted hidden information from a subject. For instance, Rubberhose was a tool that partitioned and intermixed secret data on a drive with fake secret data, each of which accessed via

16560-431: The use of cryptography is legal, laws permit investigators to compel the disclosure of encryption keys for documents relevant to an investigation. Cryptography also plays a major role in digital rights management and copyright infringement disputes with regard to digital media . The first use of the term "cryptograph" (as opposed to " cryptogram ") dates back to the 19th century—originating from " The Gold-Bug ",

16698-419: The vanguard of the pro-crypto forces. Though the battleground seems remote, the stakes are not: The outcome of this struggle may determine the amount of freedom our society will grant us in the 21st century. To the Cypherpunks, freedom is an issue worth some risk. The three masked men on the cover of that edition of Wired were prominent cypherpunks Tim May , Eric Hughes and John Gilmore . Later, Levy wrote

16836-559: The vapor find only gibberish; a world where the tools of prying are transformed into the instruments of privacy. There is only one way this vision will materialize, and that is by widespread use of cryptography. Is this technologically possible? Definitely. The obstacles are political—some of the most powerful forces in government are devoted to the control of these tools. In short, there is a war going on between those who would liberate crypto and those who would suppress it. The seemingly innocuous bunch strewn around this conference room represents

16974-414: The weapon system for firing. With small arms, caseless ammunition can reduce the weight and cost of ammunition, and simplify the firing process for increased firing rate, but the maturing technology has functionality issues. The projectile is the part of the ammunition that leaves the weapon and has the effect on the target. This effect is usually either kinetic (e.g., as with a standard bullet) or through

17112-533: Was "Minimal Key Lengths for Symmetric Ciphers to Provide Adequate Commercial Security". It suggested 75 bits was the minimum key size to allow an existing cipher to be considered secure and kept in service. At the time, the Data Encryption Standard with 56-bit keys was still a US government standard, mandatory for some applications. Other papers were critical analysis of government schemes. "The Risks of Key Recovery, Key Escrow, and Trusted Third-Party Encryption", evaluated escrowed encryption proposals. Comments on

17250-525: Was a message tattooed on a slave's shaved head and concealed under the regrown hair. Other steganography methods involve 'hiding in plain sight,' such as using a music cipher to disguise an encrypted message within a regular piece of sheet music. More modern examples of steganography include the use of invisible ink , microdots , and digital watermarks to conceal information. In India, the 2000-year-old Kama Sutra of Vātsyāyana speaks of two different kinds of ciphers called Kautiliyam and Mulavediya. In

17388-504: Was added to the Oxford English Dictionary . The Cypherpunks mailing list was started in 1992, and by 1994 had 700 subscribers. At its peak, it was a very active forum with technical discussions ranging over mathematics, cryptography, computer science, political and philosophical discussion, personal arguments and attacks, etc., with some spam thrown in. An email from John Gilmore reports an average of 30 messages

17526-480: Was an inspiration for CryptoParty decades later to such an extent that A Cypherpunk's Manifesto is quoted at the header of its Wiki, and Eric Hughes delivered the keynote address at the Amsterdam CryptoParty on 27 August 2012. Cypherpunks list participants included many notable computer industry figures. Most were list regulars, although not all would call themselves "cypherpunks". The following

17664-471: Was created, there were many contests to break it). The US government had also tried to subvert cryptography through schemes such as Skipjack and key escrow. It was also not widely known that all communications were logged by government agencies (which would later be revealed during the NSA and AT&T scandals ) though this was taken as an obvious axiom by list members. The original cypherpunk mailing list, and

17802-542: Was finally won in 1978 by Ronald Rivest , Adi Shamir , and Len Adleman , whose solution has since become known as the RSA algorithm . The Diffie–Hellman and RSA algorithms , in addition to being the first publicly known examples of high-quality public-key algorithms, have been among the most widely used. Other asymmetric-key algorithms include the Cramer–Shoup cryptosystem , ElGamal encryption , and various elliptic curve techniques . A document published in 1997 by

17940-499: Was first published about ten years later by Friedrich Kasiski . Although frequency analysis can be a powerful and general technique against many ciphers, encryption has still often been effective in practice, as many a would-be cryptanalyst was unaware of the technique. Breaking a message without using frequency analysis essentially required knowledge of the cipher used and perhaps of the key involved, thus making espionage, bribery, burglary, defection, etc., more attractive approaches to

18078-447: Was in a 1993 Wired article by Steven Levy titled Crypto Rebels : The people in this room hope for a world where an individual's informational footprints—everything from an opinion on abortion to the medical record of an actual abortion—can be traced only if the individual involved chooses to reveal them; a world where coherent messages shoot around the globe by network and microwave, but intruders and feds trying to pluck them out of

18216-488: Was indeed possible by presenting the Diffie–Hellman key exchange protocol, a solution that is now widely used in secure communications to allow two parties to secretly agree on a shared encryption key . The X.509 standard defines the most commonly used format for public key certificates . Diffie and Hellman's publication sparked widespread academic efforts in finding a practical public-key encryption system. This race

18354-460: Was legally a munition and fell under ITAR, and the key length restrictions in the EAR was not removed until 2000. In 1995 Adam Back wrote a version of the RSA algorithm for public-key cryptography in three lines of Perl and suggested people use it as an email signature file: Vince Cate put up a web page that invited anyone to become an international arms trafficker; every time someone clicked on

18492-570: Was new and significant. Computer use has thus supplanted linguistic cryptography, both for cipher design and cryptanalysis. Many computer ciphers can be characterized by their operation on binary bit sequences (sometimes in groups or blocks), unlike classical and mechanical schemes, which generally manipulate traditional characters (i.e., letters and digits) directly. However, computers have also assisted cryptanalysis, which has compensated to some extent for increased cipher complexity. Nonetheless, good modern ciphers have stayed ahead of cryptanalysis; it

18630-414: Was of relatively simple design and build (e.g., sling-shot, stones hurled by catapults), but as weapon designs developed (e.g., rifling ) and became more refined, the need for more specialized ammunition increased. Modern ammunition can vary significantly in quality but is usually manufactured to very high standards. For example, ammunition for hunting can be designed to expand inside a target, maximizing

18768-518: Was probably the first automatic cipher device , a wheel that implemented a partial realization of his invention. In the Vigenère cipher , a polyalphabetic cipher , encryption uses a key word , which controls letter substitution depending on which letter of the key word is used. In the mid-19th century Charles Babbage showed that the Vigenère cipher was vulnerable to Kasiski examination , but this

18906-496: Was seen as anathema by many on the list. This was an issue that provoked strong opposition and brought many new recruits to the cypherpunk ranks. List participant Matt Blaze found a serious flaw in the scheme, helping to hasten its demise. Steven Schear first suggested the warrant canary in 2002 to thwart the secrecy provisions of court orders and national security letters . As of 2013, warrant canaries are gaining commercial acceptance. An important set of discussions concerns

19044-533: Was the Caesar cipher , in which each letter in the plaintext was replaced by a letter three positions further down the alphabet. Suetonius reports that Julius Caesar used it with a shift of three to communicate with his generals. Atbash is an example of an early Hebrew cipher. The earliest known use of cryptography is some carved ciphertext on stone in Egypt ( c.  1900 BCE ), but this may have been done for

#825174