Cryptography

Cryptography

The science of encrypting and hiding information.

Cyphers

Methods of moving letters around or jumbling them in a different sequence.

Cryptanalysis

The process of analyzing available information to retrieve the encrypted message.

Differential cryptanalysis

Analyzing differences between input plaintext and output ciphertext to determine the key used.

Linear cryptanalysis

A method that uses plaintext and ciphertext together to deduce the encryption key.

Cryptographic operations

Actions to hide data, resist forgery, prevent unauthorized changes, enforce policy, and exchange keys.

Algorithm and key

Components used to perform cryptographic operations.

Encryption

A cryptographic operation that converts plaintext into ciphertext.

Hashing

A process that takes input and reduces it to a unique, irreversible number known as a hash.

Digital signatures

A cryptographic technique for verifying the authenticity and integrity of a message.

Substitution

The replacement of items with different items in the encryption process.

Transposition

The rearrangement of the order of items in the encryption process.

Keyspace

The set of all possible key values for a cryptographic system.

Diffusion

A property where a change in plaintext results in multiple changes in ciphertext.

Confusion

The randomization of output where each ciphertext character relies on various parts of the key.

Obfuscation

The process of masking an item to make it unreadable but still usable.

Perfect forward secrecy

A property that ensures a derived key remains secure even if the originating key is compromised.

Security through obscurity

A security principle that relies on keeping the design or implementation secret.

Transposition cipher

A cipher that changes the order of letters with the same letters.

Plaintext

The original unencrypted data.

Ciphertext

The output data that has been encrypted.

Algorithm

A step-by-step procedure for solving a problem in a finite number of steps.

Symmetric algorithm

An algorithm where the same key is used for both encryption and decryption.

Asymmetric algorithm

An algorithm that uses a pair of keys (public and private) for encryption and decryption.

Key

A special piece of data used in the encryption and decryption processes.

Exclusive OR (XOR)

A bitwise function applied to data that relies on the secrecy of the key.

Shift cipher

A cipher where a letter is shifted a specified number of places in the alphabet.

ROT 13

A letter rotation of 13 positions in the alphabet.

Vigenere cipher

A polyalphabetic substitution cipher that depends on a password.

Key management

The processes of exchange, storage, safeguarding, and revocation of keys.

Salting

A technique that provides sufficient input for low entropy items to hash functions.

Hashing function

A mathematical function that produces a unique output for a given input.

One way function

A function where retrieving the plaintext from ciphertext is not feasible.

Hash

The output of a hashing algorithm for a specific input.

MAC (Message Authentication Code)

A code used to verify the integrity and authenticity of a message.

HMAC

Hash-based message authentication code, a specialized type of MAC.

Collision attack

A method where an attacker finds two different inputs that produce the same hash value.

Message digest

The output hash created from data input into a hashing algorithm.

MD2

A hashing algorithm that produces a 128-bit hash from input data of any length.

MD4

A fast hashing algorithm that is vulnerable to attacks.

MD5

A hashing algorithm known for its vulnerability to collision attacks.

SHA (Secure Hash Algorithm)

A set of hash algorithms designed by NIST.

SHA-1

A hashing function that produces a 160-bit hash and is used in DSA.

SHA-2

An improved hashing algorithm with no known collision attacks against SHA-256.

SHA-3

A hashing algorithm different from previous versions, resistant to known attacks.

RIPEMD

A hashing function designed for integrity evaluation, known for collision problems.

DES (Data Encryption Standard)

A symmetric block cipher that segments data into specified block sizes.

3DES

An encryption method that applies the DES algorithm three times with three keys.

AES

An advanced encryption standard that supports message authentication.

RC4

A fast stream cipher that encrypts plaintext bit by bit.

Blowfish

A block cipher that encrypts a 64-bit input block into 32-bit words.

Twofish

A block cipher using 128-bit blocks and variable length keys.

ECB (Electronic Codebook)

The simplest cipher operation mode, encrypting each block separately.

CBC (Cipher Block Chaining)

A block mode where each block is XORed with the previous ciphertext before encryption.

Counter Mode (CTM)

Uses a counter function to generate a nonce for each block encryption.