CH17 Security

"Eavesdropper"

"a person who intercepts data being transmitted."

"Plaintext"

"the original text/document/message before it is put through an encryption algorithm."

"Ciphertext"

"the product when plaintext is put through an encryption algorithm."

"Block cipher"

"the encryption of a number of contiguous bits in one go rather than one bit at a time."

"Stream cipher"

"the encryption of bits in sequence as they arrive at the encryption algorithm."

"Block chaining"

"form of encryption

"Symmetric encryption"

"encryption in which the same secret key is used to encrypt and decrypt messages."

"Key distribution problem"

"security issue inherent in symmetric encryption arising from the fact that

"Asymmetric encryption"

"encryption that uses public keys (known to everyone) and private keys (secret keys)."

"Public key"

"encryption/decryption key known to all users."

"Private key"

"encryption/decryption key which is known only to a single user/computer."

"Quantum cryptography"

"cryptography based on the laws of quantum mechanics (the properties of photons)."

"Quantum key distribution (QKD)"

"protocol which uses quantum mechanics to securely send encryption keys over fibre optic networks."

"Qubit"

"the basic unit of a quantum of information (quantum bit)."

"Secure Sockets Layer (SSL)"

"security protocol used when sending data over the internet."

"Transport Layer Security (TLS)"

"a more up-to-date version of SSL."

"Handshake"

"the process of initiating communication between two devices. This is initiated by one device sending a message to another device requesting the exchange of data."

"Session caching"

"function in TLS that allows a previous computer session to be 'remembered'

"Certificate authority (CA)"

"commercial organisation used to generate a digital certificate requested by website owners or individuals."

"Public key infrastructure (PKI)"

"a set of protocols

"Digital signature"

"electronic way of validating the authenticity of digital documents (that is

"Digest"

"a fixed-size numeric representation of the contents of a message produced from a hashing algorithm. This can be encrypted to form a digital signature."

"Hashing algorithm (cryptography)"

"a function which converts a data string into a numeric string which is used in cryptography."

"Digital certificate"

"an electronic document used to prove the identity of a website or individual. It contains a public key and information identifying the website owner or individual