Cryptography Flashcards
Algorithm
A computing procedure designed to perform a task such as encryption, decryption, compression, or hashing.
Certificate
A digitally signed, special block of data that contains a public key and the identifying information for the entity, or principal, that owns the associated private key.
Certificate Authority (CA)
A trusted entity or third party that issues and signs public key certificates, thereby attesting to the validity of the public keys.
Ciphertext/ Cryptogram
This is the enciphered, encrypted, or scrambled form of a message.
Collisions
Where two different messages would provide the same hash or digest value.
Cryptanalysis
The practice of defeating the protective properties of cryptography. Reading protected information, altering messages or integrity values, and violating authentication schemes are all forms of cryptanalysis. The practice of testing cryptographic algorithms to determine their strength or resistance to compromise is also a form of cryptanalysis.
Cryptography
The word cryptography is based on the Greek words “kryptos” (hidden) and “grafi” (writing). It is a mathematical manipulation of information that prevents the information from being disclosed or altered.
Cryptology
The study of cryptography and cryptanalysis,
Cryptanalysis
The practice of defeating the protective properties of cryptography.
Cryptovariable (key)
The (often-secret) value used in the transformation of the message in a cryptographic operation that controls the operation of the algorithm in a unique, predictable manner.
Decipher/ decrypt/ decode
Descrambling an encrypted message and converting it into plaintext.
Digital Signature
Proves that the message has not been altered (Message Integrity), and it proves who sent the message (Proof of Origin and non-repudiation).
Electronic Code Book (ECB)
Each block of plaintext is independently encrypted into a respective block of ciphertext. This can be down in parallel.
Encrypt/ encipher
Scrambling a plaintext message by using an algorithm, usually in conjunction with a key.
Exclusive-OR (XOR)
A basic transformation technique and another name for binary addition.
Hash Functions
Used to ensure message integrity. For example, when a message is sent over a communications channel, it may be altered either accidentally or intentionally while in transit.
Initialization Vector (IV)
A random value that is XOR’d with the plaintext message before encryption.
Kerckhoff’s Principle
States that the strength cryptosystem is based on the secrecy of the key and not on the secrecy of the algorithm.
Key Clustering
A weakness that would exist in a cryptosystem if two different keys would generate the same ciphertext from the same plaintext.
Key space
The total number of keys available to the user of a cryptosystem.
Non-repudiation
A security service by which evidence is maintained so that the sender and recipient of data cannot deny having participated in the communication. Referred to individually as non-repudiation of origin and non-repudiation of receipt.
Plaintext/ Cleartext
This is the natural or human-readable form of a message.
Registration Authority (RA)
The primary organization that verifies a certificate Applicant’s information and identity.
Scytale Rod
A simple transposition cipher system that employs a rod of a certain thickness around which was wrapped a long, thin strip of parchment.
Secure HTTP (S-HTTP)
A protocol for transmitting data securely over the World Wide Web designed to transmit individual messages securely.
Secure Sockets Layer (SSL/TLS)
Uses two keys to encrypt data: a public key known to everyone and a private or secret key known only to the recipient of the message.
Synchronous and Self-synchronous
An algorithm in which the keystream is generated based on the original key, bit-by-bit, in sync with the arrival of the plaintext.
Transport Layer Security (TLS)
A protocol that guarantees privacy and data integrity between client/ server applications communicating over the Internet.
Work Factor
An estimate of the effort/ time needed to overcome a protective measure by an attacker with specified expertise and resources.
