7-cryptography

Computer Security

The practice of protecting computer systems and data from theft, damage, or unauthorized access.

Cryptography

The science of secure communication through the use of codes and ciphers.

Secure Communication

The need for confidentiality, authentication, and message integrity in communication.

Encryption

The process of converting plaintext into ciphertext to secure the information.

Authentication

Verifying the identity of the sender or receiver in a communication.

Symmetric Encryption

Encryption method where the same key is used for both encryption and decryption.

Asymmetric Encryption

Encryption method where different keys are used for encryption and decryption.

Key Strength

The security level of an encryption algorithm determined by the length and complexity of the key.

Caesar Cipher

A substitution cipher where each letter in the plaintext is shifted a certain number of places down or up the alphabet.

Substitution Cipher

A method of encryption where units of plaintext are replaced with ciphertext according to a regular system.

Transposition Cipher

A method of encryption where the positions of characters in the plaintext are shifted according to a regular system.

Cryptanalysis

The process of analyzing and breaking encryption codes to decipher the original message.

Data Encryption Standard (DES)

A widely used block cipher algorithm for securing data.

Data Encryption Standard (DES)

A symmetric encryption algorithm that uses a 56-bit key and operates on 64-bit blocks of data.

TripleDES

A symmetric encryption algorithm that applies the DES algorithm three times in succession for increased security.

Symmetric Encryption

Encryption method that uses a single key for both encryption and decryption.

Asymmetric Encryption

Encryption method that uses a pair of keys - public key for encryption and private key for decryption.

RSA

A popular asymmetric encryption algorithm developed by Rivest, Shamir, and Adleman, utilizing variable key sizes.

El Gamal

An asymmetric encryption algorithm developed by Taher ElGamal, less common than RSA but used in protocols like PGP.

Man-in-the-middle Attack

A security breach where an attacker intercepts and potentially alters communication between two parties.

Session-Key Encryption

A method that combines symmetric and asymmetric encryption by using asymmetric encryption to securely exchange a symmetric session key.

Pretty Good Privacy (PGP)

Encryption program used for securing emails, combining RSA, TripleDES, and other algorithms.

Key Agreement

A method in asymmetric encryption where two parties generate a shared secret key by exchanging only public keys.

Diffie-Hellman

The first key agreement algorithm allowing secure exchange of keys without prior shared information, invented by Diffie and Hellman.

Authentication

The process of verifying the identity of a user or the integrity of data, often achieved through technologies like message digests, digital signatures, and public key infrastructure.

Authentication Protocols

Set of rules governing data communication related to authentication between server and user.

Transformed Password

Password altered using one-way function before transmission to prevent eavesdropping but not replay.

Challenge-Response

Server sends a random value (challenge) to the client along with authentication request to protect against replay.

Time Stamp

Authentication from client to server must have time-stamp embedded to protect against replay, depending on clock synchronization.

One-Time Password

New password obtained by passing user-password through one-way function n times to protect against replay and eavesdropping.

Kerberos

Authentication service using symmetric key encryption and a key distribution center for user access privilege management.

Personal Tokens

Hardware devices generating unique strings used with passwords for authentication, including different types like storage tokens and synchronous one-time password generators.

Biometrics

Authentication using biological characteristics like fingerprint, voice, handwriting, face, retinal scan, and hand geometry recognition.

Iris Recognition

Authentication method utilizing the unique patterns in people's irises for identification purposes.

Digital Signatures

Data item accompanying digitally encoded message providing source guarantee and proof of data integrity.

Digital Certificates

Signed statement by a trusted party confirming another party's public key ownership, allowing authorization by a root CA.

Cryptanalysis

Practice of analyzing and breaking cryptography, with resistance proportional to key size and methods for safeguarding keys like encryption and smart cards.