Simulation
Simulation is a computational process designed to predict the behavior of a real-world or
physical system. Simulation is used to study a system’s behavior prior to building it by
performing “What if” scenarios.
• Simulation Model Types include: Discrete time simulation, Discrete event simulation,
Monte Carlo simulation, Monte Carlo simulation
• Discrete time simulation
o Models continuous systems that change over time.
o A computational simulation of systems that change at discrete times
o Usually driven by uniformly spaced clock ticks
• Discrete event simulation
o Models a system over time.
o Events drive the simulation forward
• Monte Carlo simulation
o A mathematical technique that predicts possible outcomes of an uncertain event.
o Relies on repeated random sampling to obtain numerical results.
• Financial simulation
o Focuses on the financial aspects of a business, such as budgeting, forecasting, and
investment decisions.
• Encryption
o the process of encoding information
o converts original representation of information, known as plaintext, into an
alternative form known as ciphertext
• Authentication
o the act of proving the identity of a computer system user.
• There are two main types of encryption systems:
o Symmetric Encryption
o Asymmetric Encryption
• Symmetric Encryption
o Uses a single secret password or key to encrypt and decrypt data.
o The simplest and most used form of encryption
o Fast and efficient
• Asymmetric Encryption (aka public key cryptography)
o Uses two keys for encryption and decryption.
o A public key, shared among users, can either encrypt or decrypt the data.
o A private key can also encrypt or decrypt data, not shared among users.
• Encryption algorithms
o Advanced Encryption Standard (AES) – a form of symmetric encryption
o Rivest-Shamir-Adleman (RSA) – a form of asymmetric encryption
• Hash Algorithm
o a mathematical function that converts a numerical input value into another
compressed numerical value
o SHA (Secure Hash Algorithm) most popular
o Collisions occur when two inputs have the same hash digest
• Base64 Encoding
o A binary-to-text encoding
o The bits in a sequence of 8-bit bytes (octets) are taken 6-bits at a time (sextets)
o Each 6-bit group is translated to a letter using a lookup table
• Digital Certificate - a trusted document that contains
o a public key,
o the identity of the certificate's owner, and
o a digital signature from a trusted Certificate Authority
• A Certificate Authority (CA) is an entity that issues digital certificates
• Application – Encrypted Message Transfer
1. Sender obtains recipient's public key
2. Encrypt message with public key
3. Transfer encrypted message
4. Only the recipient can decrypt encrypted message
• Application – Digital Signature
• Signer hashes document to a unique digest
• Digest is encrypted with signer's private key to a digital signature
• Document and digital signature are transmitted to recipient
• Recipient decrypts digital signature with signer's public key to document hash
• Recipient hashes document with same hash algorithm
• If hashes match, the signature is verified.
• Application - Transport Layer Security (TLS)
• protects data sent between systems
• uses a combination of symmetric and asymmetric cryptography
• asymmetric cryptography for securely generating and exchanging a session key
• symmetric cryptography for fast, and secure data exchange
• Authentication is the act of proving the identity of a computer system user
• Password attacks: brute force attack, dictionary attack
• A brute force attack uses password-cracking software to generate every possible
combination of letters, numerals, and symbols
• A dictionary attack helps hackers guess your password by stepping through a dictionary
containing word lists in common languages
• Multifactor authentication is a layered approach to securing data and applications where a
system requires a user to present a combination of two or more credentials to verify a
user’s identity for login