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Elliptic-curve Diffie–Hellman
Elliptic-curve Diffie–Hellman (ECDH) is a key agreement protocol that allows two parties, each having an elliptic-curve public–private key pair, to establish a shared secret over an insecure channel. This shared secret may be directly used as a key, or to derive another key. The key, or the derived key, can then be used to encrypt subsequent communications using a symmetric-key cipher. It is a variant of the Diffie–Hellman protocol using elliptic-curve cryptography. Key establishment protocol The following example illustrates how a shared key is established. Suppose Alice wants to establish a shared key with Bob, but the only channel available for them may be eavesdropped by a third party. Initially, the domain parameters (that is, (p, a, b, G, n, h) in the prime case or (m, f(x), a, b, G, n, h) in the binary case) must be agreed upon. Also, each party must have a key pair suitable for elliptic curve cryptography, consisting of a private key d (a randomly selected intege ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key Agreement
In cryptography, a key-agreement protocol is a protocol whereby two or more parties can agree on a key in such a way that both influence the outcome. If properly done, this precludes undesired third parties from forcing a key choice on the agreeing parties. Protocols that are useful in practice also do not reveal to any eavesdropping party what key has been agreed upon. Many key exchange systems have one party generate the key, and simply send that key to the other party—the other party has no influence on the key. Using a key-agreement protocol avoids some of the key distribution problems associated with such systems. Protocols where both parties influence the final derived key are the only way to implement perfect forward secrecy. Exponential key exchange The first publicly knownSee Diffie–Hellman key exchange for a more complete history of both the secret and public development of public-key cryptography. public-key agreement protocol that meets the above criteria was the Di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key Derivation Function
In cryptography, a key derivation function (KDF) is a cryptographic algorithm that derives one or more secret keys from a secret value such as a master key, a password, or a passphrase using a pseudorandom function (which typically uses a cryptographic hash function or block cipher). KDFs can be used to stretch keys into longer keys or to obtain keys of a required format, such as converting a group element that is the result of a Diffie–Hellman key exchange into a symmetric key for use with AES. Keyed cryptographic hash functions are popular examples of pseudorandom functions used for key derivation. History The first deliberately slow (key stretching) password-based key derivation function was called "crypt" (or "crypt(3)" after its man page), and was invented by Robert Morris in 1978. It would encrypt a constant (zero), using the first 8 characters of the user's password as the key, by performing 25 iterations of a modified DES encryption algorithm (in which a 12-bit numbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forward Secrecy
In cryptography, forward secrecy (FS), also known as perfect forward secrecy (PFS), is a feature of specific key agreement protocols that gives assurances that session keys will not be compromised even if long-term secrets used in the session key exchange are compromised. For HTTPS, the long-term secret is typically the private key of the server. Forward secrecy protects past sessions against future compromises of keys or passwords. By generating a unique session key for every session a user initiates, the compromise of a single session key will not affect any data other than that exchanged in the specific session protected by that particular key. This by itself is not sufficient for forward secrecy which additionally requires that a long-term secret compromise does not affect the security of past session keys. Forward secrecy protects data on the transport layer of a network that uses common Transport Layer Security protocols, including OpenSSL, when its long-term secret keys are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skype
Skype () is a proprietary telecommunications application operated by Skype Technologies, a division of Microsoft, best known for VoIP-based videotelephony, videoconferencing and voice calls. It also has instant messaging, file transfer, debit-based calls to landline and mobile telephones (over traditional telephone networks), and other features. Skype is available on various desktop, mobile, and video game console platforms. Skype was created by Niklas Zennström, Janus Friis, and four Estonian developers and first released in August 2003. In September 2005, eBay acquired Skype for $2.6 billion. In September 2009, Silver Lake, Andreessen Horowitz, and the Canada Pension Plan Investment Board bought 65% of Skype for $1.9 billion from eBay, valuing the business at $2.92 billion. In May 2011, Microsoft bought Skype for $8.5 billion and used it to replace their Windows Live Messenger. As of 2011, most of the development team and 44% of all the division' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facebook Messenger
Messenger is a proprietary instant messaging app and platform developed by Meta Platforms. Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, released standalone iOS and Android apps in 2011, and released standalone Facebook Portal hardware for Messenger calling in 2018. In April 2015, Facebook launched a dedicated website interface, Messenger.com, and separated the messaging functionality from the main Facebook app, allowing users to use the web interface or download one of the standalone apps. In April 2020, Facebook released a Messenger desktop app for Windows and macOS. Messenger is used to send messages and exchange photos, videos, stickers, audio, and files, and also react to other users' messages and interact with bots. The service also supports voice and video calling. The standalone apps support using multiple accounts, conversations with optional end-to-end encryption, and playing games. History Following tests o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WhatsApp
WhatsApp (also called WhatsApp Messenger) is an internationally available freeware, cross-platform, centralized instant messaging (IM) and voice-over-IP (VoIP) service owned by American company Meta Platforms (formerly Facebook). It allows users to send text and voice messages, make voice and video calls, and share images, documents, user locations, and other content. WhatsApp's client application runs on mobile device A mobile device (or handheld computer) is a computer small enough to hold and operate in the hand. Mobile devices typically have a flat LCD or OLED screen, a touchscreen interface, and digital or physical buttons. They may also have a physica ...s, and can be accessed from computers. The service requires a cellular network, cellular telephone number, mobile telephone number to sign up. In January 2018, WhatsApp released a standalone business app called WhatsApp Business which can communicate with the standard WhatsApp client. The client application was cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal (software)
Signal is a cross-platform centralized encrypted instant messaging service developed by the non-profit Signal Foundation and its subsidiary, the Signal Messenger LLC. Users can send one-to-one and group messages, which can include files, voice notes, images and videos. It can also be used to make one-to-one and group voice and video calls. The Android version also optionally functions as an SMS app, but this functionality will be removed in 2023. Signal uses standard cellular telephone numbers as identifiers and secures all communications to other Signal users with end-to-end encryption. The client software includes mechanisms by which users can independently verify the identity of their contacts and the integrity of the data channel. Signal's software is free and open-source. Its mobile clients are published under the GPL-3.0-only license, while the desktop client and server are published under the AGPL-3.0-only license. The official Android app generally uses the propr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Protocol
The Signal Protocol (formerly known as the TextSecure Protocol) is a non- federated cryptographic protocol that can be used to provide end-to-end encryption for voice calls and instant messaging conversations. The protocol was developed by Open Whisper Systems in 2013 and was first introduced in the open-source TextSecure app, which later became Signal. Several closed-source applications have implemented the protocol, such as WhatsApp, which is said to encrypt the conversations of "more than a billion people worldwide" or Google who provides end-to-end encryption by default to all RCS-based conversations between users of their Messages app for one-to-one conversations. Facebook Messenger also say they offer the protocol for optional Secret Conversations, as does Skype for its Private Conversations. The protocol combines the Double Ratchet algorithm, prekeys, and a triple Elliptic-curve Diffie–Hellman (3-DH) handshake, and uses Curve25519, AES-256, and HMAC-SHA256 as primitive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
End-to-end Encryption
End-to-end encryption (E2EE) is a system of communication where only the communicating users can read the messages. In principle, it prevents potential eavesdroppers – including telecom providers, Internet providers, malicious actors, and even the provider of the communication service – from being able to access the cryptographic keys needed to decrypt the conversation. End-to-end encryption is intended to prevent data being read or secretly modified, other than by the true sender and recipient(s). The messages are encrypted by the sender but the third party does not have a means to decrypt them, and stores them encrypted. The recipients retrieve the encrypted data and decrypt it themselves. Because no third parties can decipher the data being communicated or stored, for example, companies that provide end-to-end encryption are unable to hand over texts of their customers' messages to the authorities. In 2022, the UK's Information Commissioner's Office, the government body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line (software)
Line is a freeware app for instant communications on electronic devices such as smartphones, tablet computers and personal computers. Line users exchange: texts, images, video and audio and conduct free VoIP conversations and video conferences. In addition, Line is a platform providing various services including: digital wallet as Line Pay, news stream as LINE Today, video on demand as Line TV and digital comic distribution as Line Manga and Line Webtoon. The service is operated by Line Corporation, a Tokyo-based subsidiary of Z Holdings. Line was launched in Japan in June 2011 by NHN Japan, a subsidiary of Naver Corporation. Because it was tailored to Japanese consumers' tastes and offered free smartphone calls as well as texting, with the help of a massive marketing campaign it quickly outpaced its existing rival KakaoTalk for the Japanese market. It reached 100 million users within 18 months and 200 million users six months later. Line became Japan's largest social network i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Language Binding
In programming and software design, binding is an application programming interface (API) that provides glue code specifically made to allow a programming language to use a foreign library or operating system service (one that is not native to that language). Characteristics Binding generally refers to a mapping of one thing to another. In the context of software libraries, bindings are wrapper libraries that bridge two programming languages, so that a library written for one language can be used in another language. Many software libraries are written in system programming languages such as C or C++. To use such libraries from another language, usually of higher-level, such as Java, Common Lisp, Scheme, Python, or Lua, a binding to the library must be created in that language, possibly requiring recompiling the language's code, depending on the amount of modification needed. However, most languages offer a foreign function interface, such as Python's and OCaml's ctypes, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Language
C (''pronounced like the letter c'') is a general-purpose computer programming language. It was created in the 1970s by Dennis Ritchie, and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems, device drivers, protocol stacks, though decreasingly for application software. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the most widely used programming languages, with C compilers available for practically all modern computer architectures and operating systems. C has be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
