SecrecySecrecy is the practice of hiding information from certain individuals or groups who do not have the "need to know", perhaps while sharing it with other individuals. That which is kept hidden is known as the secret. Secrecy is often controversial, depending on the content or nature of the secret, the group or people keeping the secret, and the motivation for secrecy. Secrecy by government entities is often decried as excessive or in promotion of poor operation; excessive revelation of information on individuals can conflict with virtues of privacy and confidentiality.
Alice and BobAlice 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.
Extended Validation CertificateAn Extended Validation Certificate (EV) is a certificate conforming to X.509 that proves the legal entity of the owner and is signed by a certificate authority key that can issue EV certificates. EV certificates can be used in the same manner as any other X.509 certificates, including securing web communications with HTTPS and signing software and documents. Unlike domain-validated certificates and organization-validation certificates, EV certificates can be issued only by a subset of certificate authorities (CAs) and require verification of the requesting entity's legal identity before certificate issuance.
Shared secretIn cryptography, a shared secret is a piece of data, known only to the parties involved, in a secure communication. This usually refers to the key of a symmetric cryptosystem. The shared secret can be a password, a passphrase, a big number, or an array of randomly chosen bytes. The shared secret is either shared beforehand between the communicating parties, in which case it can also be called a pre-shared key, or it is created at the start of the communication session by using a key-agreement protocol, for instance using public-key cryptography such as Diffie–Hellman or using symmetric-key cryptography such as Kerberos.
Power analysisPower analysis is a form of side channel attack in which the attacker studies the power consumption of a cryptographic hardware device. These attacks rely on basic physical properties of the device: semiconductor devices are governed by the laws of physics, which dictate that changes in voltages within the device require very small movements of electric charges (currents). By measuring those currents, it is possible to learn a small amount of information about the data being manipulated.
Space–time tradeoffA space–time trade-off, also known as time–memory trade-off or the algorithmic space-time continuum in computer science is a case where an algorithm or program trades increased space usage with decreased time. Here, space refers to the data storage consumed in performing a given task (RAM, HDD, etc), and time refers to the time consumed in performing a given task (computation time or response time). The utility of a given space–time tradeoff is affected by related fixed and variable costs (of, e.g.
Adversary (cryptography)In cryptography, an adversary (rarely opponent, enemy) is a malicious entity whose aim is to prevent the users of the cryptosystem from achieving their goal (primarily privacy, integrity, and availability of data). An adversary's efforts might take the form of attempting to discover secret data, corrupting some of the data in the system, spoofing the identity of a message sender or receiver, or forcing system downtime. Actual adversaries, as opposed to idealized ones, are referred to as attackers.
Diffie–Hellman key exchangeDiffie–Hellman key exchange is a mathematical method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman. DH is one of the earliest practical examples of public key exchange implemented within the field of cryptography. Published in 1976 by Diffie and Hellman, this is the earliest publicly known work that proposed the idea of a private key and a corresponding public key.
Public key fingerprintIn public-key cryptography, a public key fingerprint is a short sequence of bytes used to identify a longer public key. Fingerprints are created by applying a cryptographic hash function to a public key. Since fingerprints are shorter than the keys they refer to, they can be used to simplify certain key management tasks. In Microsoft software, "thumbprint" is used instead of "fingerprint." A public key fingerprint is typically created through the following steps: A public key (and optionally some additional data) is encoded into a sequence of bytes.
Negligible functionIn mathematics, a negligible function is a function such that for every positive integer c there exists an integer Nc such that for all x > Nc, Equivalently, we may also use the following definition. A function is negligible, if for every positive polynomial poly(·) there exists an integer Npoly > 0 such that for all x > Npoly The concept of negligibility can find its trace back to sound models of analysis. Though the concepts of "continuity" and "infinitesimal" became important in mathematics during Newton and Leibniz's time (1680s), they were not well-defined until the late 1810s.
