|
Key Exchange
Key exchange (also key establishment) is a method in cryptography by which cryptographic keys are exchanged between two parties, allowing use of a cryptographic algorithm. If the sender and receiver wish to exchange encrypted messages, each must be equipped to encrypt messages to be sent and decrypt messages received. The nature of the equipping they require depends on the encryption technique they might use. If they use a code, both will require a copy of the same codebook. If they use a cipher, they will need appropriate keys. If the cipher is a symmetric key cipher, both will need a copy of the same key. If it is an asymmetric key cipher with the public/private key property, both will need the other's public key. Channel of exchange Key exchange is done either in-band or out-of-band. The key exchange problem The key exchange problem describes ways to exchange whatever keys or other information are needed for establishing a secure communication channel so that no one els ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or '' -logia'', "study", respectively), 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 the modern age was effectively syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Signature Algorithm
The Digital Signature Algorithm (DSA) is a public-key cryptosystem and Federal Information Processing Standard for digital signatures, based on the mathematical concept of modular exponentiation and the discrete logarithm problem. DSA is a variant of the Schnorr and ElGamal signature schemes. The National Institute of Standards and Technology (NIST) proposed DSA for use in their Digital Signature Standard (DSS) in 1991, and adopted it as FIPS 186 in 1994. Four revisions to the initial specification have been released. The newest specification isFIPS 186-4 from July 2013. DSA is patented but NIST has made this patent available worldwide royalty-free. A draft version of the specificatioFIPS 186-5indicates DSA will no longer be approved for digital signature generation, but may be used to verify signatures generated prior to the implementation date of that standard. Overview The DSA works in the framework of public-key cryptosystems and is based on the algebraic properties o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Authoritarianism
Authoritarianism is a political system characterized by the rejection of political plurality, the use of strong central power to preserve the political ''status quo'', and reductions in the rule of law, separation of powers, and democratic voting. Political scientists have created many typologies describing variations of authoritarian forms of government. Authoritarian regimes may be either autocratic or oligarchic and may be based upon the rule of a party or the military. States that have a blurred boundary between democracy and authoritarianism have some times been characterized as "hybrid democracies", "hybrid regimes" or "competitive authoritarian" states. The political scientist Juan Linz, in an influential 1964 work, ''An Authoritarian Regime: Spain'', defined authoritarianism as possessing four qualities: # Limited political pluralism, is realized with constraints on the legislature, political parties and interest groups. # Political legitimacy is based upon appeals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argument From Authority
An argument from authority (''argumentum ab auctoritate''), also called an appeal to authority, or argumentum ad verecundiam, is a form of argument in which the opinion of an authority on a topic is used as evidence to support an argument. Some consider that it is used in a cogent form if all sides of a discussion agree on the reliability of the authority in the given context, and others consider it to be a fallacy to cite the views of an authority on the discussed topic as a means of supporting an argument. Overview Historically, opinion on the appeal to authority has been divided: it is listed as a non-fallacious argument as often as a fallacious argument in various sources, as some hold that it can be a strong or at least valid defeasible argument and others that it is weak or an outright fallacy. The general form of this type of argument is: Use in science Scientific knowledge is best established by evidence and experiment rather than argued through authority as authorit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Signature
A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very high confidence that the message was created by a known sender ( authenticity), and that the message was not altered in transit ( integrity). Digital signatures are a standard element of most cryptographic protocol suites, and are commonly used for software distribution, financial transactions, contract management software, and in other cases where it is important to detect forgery or tampering. Digital signatures are often used to implement electronic signatures, which includes any electronic data that carries the intent of a signature, but not all electronic signatures use digital signatures. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Legislation
Legislation is the process or result of enrolling, enacting, or promulgating laws by a legislature, parliament, or analogous governing body. Before an item of legislation becomes law it may be known as a bill, and may be broadly referred to as "legislation" while it remains under consideration to distinguish it from other business. Legislation can have many purposes: to regulate, to authorize, to outlaw, to provide (funds), to sanction, to grant, to declare, or to restrict. It may be contrasted with a non-legislative act by an executive or administrative body under the authority of a legislative act. Overview Legislation is usually proposed by a member of the legislature (e.g. a member of Congress or Parliament), or by the executive, whereupon it is debated by members of the legislature and is often amended before passage. Most large legislatures enact only a small fraction of the bills proposed in a given session. Whether a given bill will be proposed is generally a matt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Certificate Revocation List
In cryptography, a certificate revocation list (or CRL) is "a list of digital certificates that have been revoked by the issuing certificate authority (CA) before their scheduled expiration date and should no longer be trusted". CRLs are no longer required by the CA/Browser forum, as alternate certificate revocation technologies (such as OCSP) are increasingly used instead. Nevertheless, CRLs are still widely used by the CAs. Revocation states There are two different states of revocation defined in RFC 5280: ; Revoked: A certificate is irreversibly revoked if, for example, it is discovered that the certificate authority (CA) had improperly issued a certificate, or if a private-key is thought to have been compromised. Certificates may also be revoked for failure of the identified entity to adhere to policy requirements, such as publication of false documents, misrepresentation of software behaviour, or violation of any other policy specified by the CA operator or its customer. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Certificate
In cryptography, a public key certificate, also known as a digital certificate or identity certificate, is an electronic document used to prove the validity of a public key. The certificate includes information about the key, information about the identity of its owner (called the subject), and the digital signature of an entity that has verified the certificate's contents (called the issuer). If the signature is valid, and the software examining the certificate trusts the issuer, then it can use that key to communicate securely with the certificate's subject. In email encryption, code signing, and e-signature systems, a certificate's subject is typically a person or organization. However, in Transport Layer Security (TLS) a certificate's subject is typically a computer or other device, though TLS certificates may identify organizations or individuals in addition to their core role in identifying devices. TLS, sometimes called by its older name Secure Sockets Layer (SSL), is notabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Certificate Authority
In cryptography, a certificate authority or certification authority (CA) is an entity that stores, signs, and issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others (relying parties) to rely upon signatures or on assertions made about the private key that corresponds to the certified public key. A CA acts as a trusted third party—trusted both by the subject (owner) of the certificate and by the party relying upon the certificate. The format of these certificates is specified by the X.509 or EMV standard. One particularly common use for certificate authorities is to sign certificates used in HTTPS, the secure browsing protocol for the World Wide Web. Another common use is in issuing identity cards by national governments for use in electronically signing documents. Overview Trusted certificates can be used to create secure connections to a server via the Internet. A certificate i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Public Key Infrastructure
A public key infrastructure (PKI) is a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption. The purpose of a PKI is to facilitate the secure electronic transfer of information for a range of network activities such as e-commerce, internet banking and confidential email. It is required for activities where simple passwords are an inadequate authentication method and more rigorous proof is required to confirm the identity of the parties involved in the communication and to validate the information being transferred. In cryptography, a PKI is an arrangement that ''binds'' public keys with respective identities of entities (like people and organizations). The binding is established through a process of registration and issuance of certificates at and by a certificate authority (CA). Depending on the assurance level of the binding, this may be carried out by an aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Man-in-the-middle Attack
In cryptography and computer security, a man-in-the-middle, monster-in-the-middle, machine-in-the-middle, monkey-in-the-middle, meddler-in-the-middle, manipulator-in-the-middle (MITM), person-in-the-middle (PITM) or adversary-in-the-middle (AiTM) attack is a cyberattack where the attacker secretly relays and possibly alters the communications between two parties who believe that they are directly communicating with each other, as the attacker has inserted themselves between the two parties. One example of a MITM attack is active eavesdropping, in which the attacker makes independent connections with the victims and relays messages between them to make them believe they are talking directly to each other over a private connection, when in fact the entire conversation is controlled by the attacker. The attacker must be able to intercept all relevant messages passing between the two victims and inject new ones. This is straightforward in many circumstances; for example, an attacker wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ralph Merkle
Ralph C. Merkle (born February 2, 1952) is a computer scientist and mathematician. He is one of the inventors of public-key cryptography, the inventor of cryptographic hashing, and more recently a researcher and speaker on cryonics. Contributions While an undergraduate, Merkle devised Merkle's Puzzles, a scheme for communication over an insecure channel, as part of a class project. The scheme is now recognized to be an early example of public key cryptography. He co-invented the Merkle–Hellman knapsack cryptosystem, invented cryptographic hashing (now called the Merkle–Damgård construction based on a pair of articles published 10 years later that established the security of the scheme), and invented Merkle trees. The Merkle–Damgård construction is at the heart of many hashing algorithms. While at Xerox PARC, Merkle designed the Khufu and Khafre block ciphers, and the Snefru hash function. Career Merkle was the manager of compiler development at Elxsi from 1980. In 1988, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
