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Yahalom (protocol)
Yahalom is an authentication and secure key-sharing protocol designed for use on an insecure network such as the Internet. Yahalom uses a trusted arbitrator to distribute a shared key between two people. This protocol can be considered as an improved version of Wide Mouth Frog protocol (with additional protection against man-in-the-middle attack), but less secure than the Needham–Schroeder protocol. Protocol description If Alice (A) initiates the communication to Bob (B) with S is a server trusted by both parties, the protocol can be specified as follows using security protocol notation: * A and B are identities of Alice and Bob respectively * K_ is a symmetric key known only to A and S * K_ is a symmetric key known only to B and S * N_A and N_B are nonces generated by A and B respectively * K_ is a symmetric, generated key, which will be the session key of the session between A and B A \rightarrow B: A, N_A :Alice sends a message to Bob requesting communication. B \rightarro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wide Mouth Frog Protocol
The Wide-Mouth Frog protocol is a computer network authentication protocol designed for use on insecure networks (the Internet for example). It allows individuals communicating over a network to prove their identity to each other while also preventing eavesdropping or replay attacks, and provides for detection of modification and the prevention of unauthorized reading. This can be proven using Degano. The protocol was first described under the name "The Wide-mouthed-frog Protocol" in the paper "A Logic of Authentication" (1990), which introduced Burrows–Abadi–Needham logic, and in which it was an "unpublished protocol ... proposed by" coauthor Michael Burrows. Burrows, Abadi, and Needham"A Logic of Authentication" ''ACM Transactions on Computer Systems'' 8 (1990), pp. 18–36. The paper gives no rationale for the protocol's whimsical name. The protocol can be specified as follows in security protocol notation: [...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] |
Needham–Schroeder Protocol
The Needham–Schroeder protocol is one of the two key transport protocols intended for use over an insecure network, both proposed by Roger Needham and Michael Schroeder. These are: * The ''Needham–Schroeder Symmetric Key Protocol'', based on a symmetric encryption algorithm. It forms the basis for the Kerberos protocol. This protocol aims to establish a session key between two parties on a network, typically to protect further communication. * The ''Needham–Schroeder Public-Key Protocol'', based on public-key cryptography. This protocol is intended to provide mutual authentication between two parties communicating on a network, but in its proposed form is insecure. The symmetric protocol Here, Alice (A) initiates the communication to Bob B. S is a server trusted by both parties. In the communication: * A and B are identities of Alice and Bob respectively * is a symmetric key known only to A and S * is a symmetric key known only to B and S * N_A and N_B are nonces gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alice And Bob
Alice and Bob are fictional characters commonly used as placeholders in discussions about cryptographic systems and protocols, and in other science and engineering literature where there are several participants in a thought experiment. The Alice and Bob characters were invented by Ron Rivest, Adi Shamir, and Leonard Adleman in their 1978 paper "A Method for Obtaining Digital Signatures and Public-key Cryptosystems". Subsequently, they have become common archetypes in many scientific and engineering fields, such as quantum cryptography, game theory and physics. As the use of Alice and Bob became more widespread, additional characters were added, sometimes each with a particular meaning. These characters do not have to refer to people; they refer to generic agents which might be different computers or even different programs running on a single computer. Overview Alice and Bob are the names of fictional characters used for convenience and to aid comprehension. For example, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Security Protocol Notation
In cryptography, security (engineering) protocol notation, also known as protocol narrations and Alice & Bob notation, is a way of expressing a protocol of correspondence between entities of a dynamic system, such as a computer network. In the context of a formal model, it allows reasoning about the properties of such a system. The standard notation consists of a set of principals (traditionally named Alice, Bob, Charlie, and so on) who wish to communicate. They may have access to a server S, shared keys K, timestamps T, and can generate nonces N for authentication purposes. A simple example might be the following: :A\rightarrow B:\_ This states that Alice intends a message for Bob consisting of a plaintext X encrypted under shared key KA,B. Another example might be the following: :B\rightarrow A:\_ This states that Bob intends a message for Alice consisting of a nonce NB encrypted using public key of Alice. A key with two subscripts, KA,B, is a symmetric key Symmetric-ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetric Key
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between the two keys. The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link. The requirement that both parties have access to the secret key is one of the main drawbacks of symmetric-key encryption, in comparison to public-key encryption (also known as asymmetric-key encryption). However, symmetric-key encryption algorithms are usually better for bulk encryption. They have a smaller key size, which means less storage space and faster transmission. Due to this, asymmetric-key encryption is often used to exchange the secret key for symmetric-key encryption. Types Symmetric-key encryption can use either stream ciphers or block ciphers. * Stream ciphers encrypt the digits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptographic Nonce
In cryptography, a nonce is an arbitrary number that can be used just once in a cryptographic communication. It is often a random or pseudo-random number issued in an authentication protocol to ensure that old communications cannot be reused in replay attacks. They can also be useful as initialization vectors and in cryptographic hash functions. Definition A nonce is an arbitrary number used only once in a cryptographic communication, in the spirit of a nonce word. They are often random or pseudo-random numbers. Many nonces also include a timestamp to ensure exact timeliness, though this requires clock synchronisation between organisations. The addition of a client nonce ("cnonce") helps to improve the security in some ways as implemented in digest access authentication. To ensure that a nonce is used only once, it should be time-variant (including a suitably fine-grained timestamp in its value), or generated with enough random bits to ensure a insignificantly low chance of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Session Key
A session key is a single-use symmetric key used for encrypting all messages in one communication session. A closely related term is content encryption key (CEK), traffic encryption key (TEK), or multicast key which refers to any key used for encrypting messages, contrary to other uses like encrypting other keys (key encryption key (KEK) or key encryption has been made public key). Session keys can introduce complications into a system, yet they solve some real problems. There are two primary reasons to use session keys: # Several cryptanalytic attacks become easier the more material encrypted with a specific key is available. By limiting the amount of data processed using a particular key, those attacks are rendered harder to perform. # asymmetric encryption is too slow for many purposes, and all secret key algorithms require that the key is securely distributed. By using an asymmetric algorithm to encrypt the secret key for another, faster, symmetric algorithm, it's possible t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerberos (protocol)
Kerberos () is a computer-network authentication protocol that works on the basis of ''tickets'' to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner. Its designers aimed it primarily at a client–server model, and it provides mutual authentication—both the user and the server verify each other's identity. Kerberos protocol messages are protected against eavesdropping and replay attacks. Kerberos builds on symmetric-key cryptography and requires a trusted third party, and optionally may use public-key cryptography during certain phases of authentication.RFC 4556, abstract. Kerberos uses UDP port 88 by default. The protocol was named after the character '' Kerberos'' (or ''Cerberus'') from Greek mythology, the ferocious three-headed guard dog of Hades. History and development Massachusetts Institute of Technology (MIT) developed Kerberos in 1988 to protect network services provided by Project Athena. The protocol is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otway–Rees Protocol
The Otway–Rees protocol is a computer network authentication protocol designed for use on insecure networks (e.g. the Internet). It allows individuals communicating over such a network to prove their identity to each other while also preventing eavesdropping or replay attacks and allowing for the detection of modification. The protocol can be specified as follows in security protocol notation, where Alice is authenticating herself to Bob using a server S (M is a session-identifier, NA and NB are nonces): # A \rightarrow B: M,A,B,\_ # B \rightarrow S: M,A,B,\_,\_ # S \rightarrow B: M,\_,\_ # B \rightarrow A: M,\_ Note: The above steps do not authenticate B to A. This is one of the protocols analysed by Burrows, Abadi and Needham in the paper that introduced an early version of Burrows–Abadi–Needham logic. Attacks on the protocol There are a variety of attacks on this protocol currently published. Interception attacks These attacks leave the intruder with the session ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuman–Stubblebine Protocol
The Neuman–Stubblebine protocol is a computer network authentication protocol designed for use on insecure networks (e.g., the Internet). It allows individuals communicating over such a network to prove their identity to each other. This protocol utilizes time stamps, but does not depend on synchronized clocks. The protocol If Alice (A) initiates the communication to Bob (B) with S is a server trusted by both parties, the protocol can be specified as follows using security protocol notation: * A and B are identities of Alice and Bob respectively * M is a session identifier * K_ is a symmetric key known only to A and S * K_ is a symmetric key known only to B and S * N_A and N_B are nonces generated by A and B respectively * T_A and T_B are timestamps generated by A and B respectively * K_ is a generated symmetric key, which will be the session key of the session between A and B A \rightarrow B: A, N_A :Alice notified Bob of intent to initiate secure communication. B \rightarr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Wiley & Sons
John Wiley & Sons, Inc., commonly known as Wiley (), is an American multinational publishing company founded in 1807 that focuses on academic publishing and instructional materials. The company produces books, journals, and encyclopedias, in print and electronically, as well as online products and services, training materials, and educational materials for undergraduate, graduate, and continuing education students. History The company was established in 1807 when Charles Wiley opened a print shop in Manhattan. The company was the publisher of 19th century American literary figures like James Fenimore Cooper, Washington Irving, Herman Melville, and Edgar Allan Poe, as well as of legal, religious, and other non-fiction titles. The firm took its current name in 1865. Wiley later shifted its focus to scientific, technical, and engineering subject areas, abandoning its literary interests. Wiley's son John (born in Flatbush, New York, October 4, 1808; died in East Orange, New Je ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
