CyberCode Academy

In this lesson, you’ll learn about:Functional Programming with Closures:Defining closures as anonymous functions that capture values from their surrounding scope.Using closures with iterator methods like map, filter, and fold to transform data.The difference between borrowing closures and move closures, and why move semantics are required for safe multi-threaded execution.Multi-threaded Execution in Rust:Spawning threads with thread::spawn and running closures as thread entry points.Using join handles to wait for thread completion and handle potential panics.Understanding performance trade-offs between OS threads and asynchronous models, and when to prefer threads versus async/await.Inter-thread Communication with Channels:Coordinating work between threads using message-passing channels.Working with transmitters (TX) and receivers (RX), including cloning senders for multi-producer setups.Leveraging high-performance channel implementations to support multiple receivers.Synchronization and Program Lifecycle Management:How thread scheduling and sleep timing affect execution order.Ensuring clean shutdowns by closing channel senders and properly joining all threads.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Data Organization with Structs and Traits:Using structs to group data fields, methods, and associated functions.Defining shared behavior with traits instead of inheritance.Writing generic functions that operate on any type implementing a required trait.Using default trait implementations to share common behavior without repetitive code.Managing Data with Standard Collections:Vectors (Vec): Dynamic lists or stacks for storing items of the same type.HashMaps: Key–value storage with efficient lookup and removal.Specialized collections: VecDeque for double-ended queues, HashSet for set operations, and BTree collections for sorted data.Advanced Logic with Enums and Pattern Matching:Using enums as powerful data types that can hold different kinds of associated data.Enforcing safety through exhaustive pattern matching with match and if let.Core language enums:Option for representing optional values without nulls.Result for explicit and robust error handling.Practical Application and Exercises:Implementing state changes in structs using traits and methods.Building simulations that combine enums, collections, and pattern matching.Iterating over collections to calculate results based on enum variants.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Ownership and Memory Management in Rust:How Rust guarantees memory safety without a garbage collector.The difference between stack and heap memory and how data lifecycles are managed.The Mechanics of Ownership:Rust’s three core ownership rules:Every value has a single owner.Only one owner exists at a time.Values are dropped immediately when the owner goes out of scope.The distinction between moving values (invalidating the original variable) and cloning values (performing a deep copy).References and Borrowing:Using references to access data without transferring ownership.The role of lifetimes in ensuring references always point to valid data.The borrowing rules: either one mutable reference or multiple immutable references, but never both at the same time.How the dot operator automatically dereferences values for method access.Practical Application (Exercise E):Inspecting: Reading data using an immutable reference (&String).Changing: Modifying data through a mutable reference (&mut String).Eating: Passing ownership to a function, consuming the value and making it unavailable afterward.Why These Rules Matter:Preventing segmentation faults, data races, and dangling pointers.Writing safer, more reliable code despite initial compiler challenges.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Core Data Representations in Rust:Scalar types: integers (signed i and unsigned u), floating-point types (f32, f64), booleans, and Unicode char values.Compound types: tuples (accessed via indexing or destructuring) and fixed-size arrays stored on the stack, along with their practical limits.Project Organization and Reusability:Moving logic into a library file (lib.rs).Exposing functions with the pub keyword and importing them using use statements.Control Flow and Program Logic:Using if as an expression that returns a value, replacing traditional ternary operators.Working with loops: loop (including labeled breaks), while, and for.Iterating with ranges, both exclusive (0..50) and inclusive (0..=50).Understanding Rust Strings:Differences between borrowed string slices (&str) and owned, heap-allocated String types.Why UTF-8 encoding prevents direct character indexing.Safely accessing string data using iterators like .bytes(), .chars(), and .nth().Practical Application:Processing command-line arguments as vectors of strings.Applying loops and conditional logic to perform numeric operations such as summing ranges or repeatedly modifying values until a condition is met.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:The Rust Ecosystem and Tooling:Using Cargo as Rust’s package manager, build system, and documentation tool.Creating projects with cargo new, managing dependencies in Cargo.toml, and running code with cargo run.Understanding the difference between debug builds and optimized release builds.Variables and Constants:Declaring variables with let in a strongly typed language with type inference.Rust’s default immutability model and using mut for mutable values.Defining constants (const) with explicit types and compile-time evaluation.Scope and Shadowing:How variables are scoped to blocks and automatically dropped when out of scope.Using shadowing to redefine variables, including changing their type or mutability.Memory Safety Guarantees:Rust’s compile-time enforcement of memory safety.Prevention of uninitialized variable usage and undefined behavior without relying on a garbage collector.Functions and Macros:Defining functions with fn and snake_case naming conventions.Returning values using tail expressions without a semicolon.Distinguishing between functions and macros (e.g., println!).The Module System and Code Organization:Structuring projects with main.rs for binaries and lib.rs for libraries.Managing visibility with private-by-default items and the pub keyword.Bringing items into scope with use and integrating external crates.Hands-On Practice:Reinforcing concepts through guided exercises, including building a command-line program and writing functions to calculate geometric areas and volumes.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Evading Initial Detection:Payload Obfuscation: Encoding payloads multiple times to cloak them from IDS detection.Benign Carrier Injection: Hiding malicious code inside legitimate scripts (e.g., Python Base64 payloads).Custom Packaging: Using packers to compress or encrypt malware, creating unique fingerprints that bypass signature-based detection.Post-Penetration Stealth:Fileless Attacks: Running scripts directly in memory via tools like PowerShell, avoiding disk storage.Folder Cloaking: Hiding directories using CLSID entries and desktop.ini files.Alternate Data Streams (ADS): Embedding executable code in hidden NTFS streams, keeping file sizes unchanged and avoiding standard file scans.Anti-Analysis and Oversight Detection:Environmental Checks: Detecting virtual machines or sandbox environments via CPU, registry, and network adapter inspection.Evasive Countermeasures: Terminating, altering behavior, or sleeping to avoid detection during analysis.Analogy for Understanding:Think of a spy infiltrating a high-security facility:Obfuscation: Wearing a disguise to bypass guards.Fileless attacks: Building tools inside the facility without carrying weapons.ADS and cloaking: Hiding secret documents in a hidden compartment of a normal briefcase.Anti-analysis: Acting like a janitor when noticing surveillance to avoid suspicion.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Foundations of Intrusion Defense:Multi-layered defense-in-depth strategies using models like SAPSA.Difference between Intrusion Detection Systems (IDS), which alert operators, and Intrusion Prevention Systems (IPS), which can actively block threats.The challenge of balancing false positives vs. false negatives in threat detection.Detection Methodologies:Signature-based detection: Matches traffic against known attack patterns with regularly updated signatures.Anomaly detection: Builds models of normal traffic to detect deviations, including protocol and statistical anomalies.Perimeter and Access Control:Techniques like blacklisting (blocking known bad sites) and whitelisting (allowing only approved sites) to secure network entry points.Technical Tools: Snort and Security Onion:Snort: Open-source, rule-based NIDS; creating rules for logging, alerting, and traffic filtering.Security Onion: Ubuntu-based distribution integrating Snort, Suricata, and log management tools for real-time network monitoring.Intelligence-Led Security:Using reputation-based threat intelligence from providers to block risky IPs and URLs.Extending IDS/IPS beyond signature detection for proactive security.Case Study: EINSTEIN Program:Analysis of the 2015 OPM breach and how relying solely on outdated signature-based methods caused a 94% false negative rate.Highlights the importance of anomaly detection and modern threat intelligence integration.Analogy for Understanding:IDS/IPS systems are like airport security:Signature-based IDS: “No Fly List” stopping known bad actors.Anomaly detection: Behavior detection officer spotting unusual activity.Reputation feeds: International intelligence sharing, warning about suspicious travelers before they arrive.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Web Application Firewalls (WAFs):Protecting the application layer by inspecting HTTP/HTTPS and WebSocket traffic.Breaking SSL encryption to detect threats using malware signatures and logic-based anomaly detection.Deployment options: hardware, software, or cloud services; open-source examples like ModSecurity.API Gateways and Microservices Security:Acting as proxies between subscribers and backend services to prevent attacks such as cross-site scripting (XSS).Managing API keys, documentation, and subscriber catalogs.Practical configuration: using management consoles to create users and publish APIs; pentesters can fingerprint gateways to ensure security features are active.Honeypots and Deception Systems:Luring, trapping, and monitoring attackers using decoy systems.Types: low-interaction (basic interfaces), medium/high-interaction (realistic environments).Example: Cowrie SSH/Telnet honeypot for logging brute-force attempts and shell activity.Detection notes: attackers may recognize honeypots via behavioral anomalies or packet handling differences.Analogy for Understanding:Securing a digital environment is like a high-stakes gala:WAF: Security guard at the entrance checking every guest.API Gateway: Concierge controlling which rooms guests can enter.Honeypot: Decoy vault to safely observe thieves without risking real assets.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:GNS3 Platform Foundation and Image Integration:Installing GNS3 Windows All-in-One and preparing the environment for professional network emulation.Importing manufacturer-specific device images (e.g., Cisco 3745 router, ASA firewall) to run actual device code instead of generic simulators.Building a Routed Network:Configuring IP addresses and routing paths on Cisco routers.Calculating idle time to optimize host CPU usage during emulation.Establishing a functional network backbone before adding security layers.Deploying the Cisco ASA Firewall:Creating a secure network enclave with multiple security zones.Assigning security levels (Inside = 100, DMZ = 50) and managing traffic flow.Configuring explicit rules and ICMP permissions to control responses from lower- to higher-security zones.Security Testing with Kali Linux:Integrating a Kali Linux VM into the GNS3 topology for vulnerability probing.Using professional tools like Nmap and Armitage to verify firewall effectiveness.Running simulated attacks to confirm that the ASA firewall filters ports and protects internal resources.Analogy for Understanding GNS3 Emulation:Using GNS3 is like a pilot training on a full-motion flight simulator: you interact with the actual software and controls, safely practicing defensive maneuvers against cyber threats without risking a real network.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Initializing and Configuring a Cisco PIX Firewall:Physical and software setup: connecting to the RS232 console port via USB-to-serial adapter and using Putty.Navigating the Cisco IOS CLI: moving from basic prompts to privilege mode and the configuration environment (config t).Administrative tasks:Checking existing configurations with show configure.Creating local user accounts and setting privilege levels.Naming and managing interfaces, identifying Ethernet 0 as "outside" (WAN) and Ethernet 1 as "inside" (internal network).Network Architecture and Connectivity:Building a secure subnet (10.0.0.0/24) behind the firewall while connected to a local network (192.168.1.0/24).Key steps:Assign static IP addresses to internal and external interfaces.Configure routing so internal devices can reach the internet.Implement Access Control Lists (ACLs) to allow specific traffic like ICMP (ping).Set up Network Address Translation (NAT) to bridge the secure enclave with the outside network.Verification and Testing:Conduct connectivity tests and use tools like Nmap to confirm that internal devices are protected and only intended services are exposed to the public network.Analogy for Understanding Firewall Setup:Think of the firewall as a secure gatehouse for a private estate: set up the administrative office (console/user access), define roads to the mansion (inside network) vs. the public highway (outside network), and hire a guard (NAT & ACLs) to only let authorized guests through while hiding internal details from outsiders.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:Firewall Fundamentals and Windows Configuration:What a firewall is and how it mediates between network zones using rules based on source/destination addresses and ports.Windows Firewall network profiles: Domain, Private, and Public.Key practices:Application Control: Allow specific programs, block vulnerable protocols like SMB/RPC on public networks.Advanced Rules: Configure IPSec for authenticated/encrypted transmissions; set granular inbound/outbound rules.Logging and Analysis: Use tools to convert large text logs into graphical summaries to detect anomalies.Linux Firewall Management with IPTables:IPTables chains: Input, Forward, and Output.Key practices:Block Traffic: Drop packets by source IP or destination port.Advanced Filtering: Flood protection, limit concurrent SSH sessions, divert unauthorized Telnet traffic to a honeypot.Audit Activity: Monitor dropped packets in system logs for attack analysis.Advanced Rule Management and Verification:Use GUI tools like Firewall Builder for Linux/Cisco (ASA/PIX) platforms to simplify rule creation and detect issues like “rule shadowing.”Verify policies with Port Tester to ensure ports are open or blocked as intended.Analogy for Understanding Firewalls:Think of a firewall as a security team at a gated campus: rules dictate who enters (Input), moves between buildings (Forward), and exits with equipment (Output). Tools like Firewall Builder are blueprints to prevent conflicts, while port testing acts as surprise inspections to catch accidental backdoors.Best Practices:Apply proper configuration, audit logs, verify rules, and ensure security policies are effective across Windows and Linux environments.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:The fundamentals of VPNs and IPsecKey management and Security Associations (SA)IPsec protocols: AH vs. ESPOperational modes: Transport vs. Tunnel1. VPNs and IPsec FundamentalsA VPN (Virtual Private Network) creates a secure, logical tunnel over the public internet, allowing private communication without costly dedicated lines.IPsec (Internet Protocol Security) operates at the network layer and supports both IPv4 and IPv6.Security services provided by IPsec include:Access Control – Only authorized users can send/receive dataData Origin Authentication – Verify the source of the packetIntegrity Protection – Ensure data hasn’t been tampered withConfidentiality – Encrypt the packet contentsAnti-Replay – Detect and discard duplicated or malicious packets2. IPsec Framework and Key ManagementEncryption algorithms: DES, 3DES, AES for confidentialityIntegrity algorithms: MD5, SHA to create digital signatures (MACs)Key exchange: Diffie-Hellman ensures a shared secret is established securely3. Security Associations (SA) and IKEAn SA is a unidirectional logical connection, identified by:SPI (Security Parameter Index)Destination IP addressBidirectional communication requires two SAs.IKE (Internet Key Exchange) establishes SAs and manages keys:IKE Phase 1: Creates a secure management tunnel (authenticates parties, negotiates algorithms, performs Diffie-Hellman exchange)IKE Phase 2: Sets up the actual data tunnel (negotiates AH/ESP and operational mode)IKEv2 is the modern version, supporting NAT traversal and keep-alive, and is widely used in 5G networks.4. IPsec Protocols: AH vs. ESPProtocolSecurity ProvidedNotesAH (Authentication Header)Integrity & authenticationDoes not encrypt; ignores changing IP header fields like TTLESP (Encapsulating Security Payload)Integrity, authentication, encryptionPreferred protocol for most VPNs and mandatory for 5G5. Operational Modes: Transport vs. TunnelTransport Mode: Only the payload is encrypted; original IP header is visibleTunnel Mode: Entire original IP packet (header + payload) is encrypted inside a new IP packetMost common setup: Tunnel Mode + ESP (encrypts everything and ensures privacy)Analogy:Transport Mode: Transparent envelope with coded letter inside – address is visible, content protectedTunnel Mode: Envelope inside an opaque crate – both content and sender/receiver are hiddenYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:The purpose and security objectives of TLS/SSLHow a simplified "Toy TLS" model illustrates key conceptsHow actual TLS works, including handshake, key derivation, and record protocolsThe role of cipher suites and secure data transfer1. Core Security Services of TLS/SSL TLS (Transport Layer Security) is designed to protect communications over insecure networks. Its four main security services are:Authentication – Verify the identities of client and server using digital certificates.Encryption – Protect data from being read by unauthorized parties.Integrity Protection – Detect any changes or tampering of transmitted data.Replay Attack Prevention – Stop attackers from resending valid data to repeat actions (like fraudulent payments).2. Toy TLS: A Conceptual Model The "Toy TLS" model is a simplified way to understand TLS: Handshake & Key DerivationStep 1: Client (Alice) and server (Bob) authenticate each other with certificates.Step 2: They exchange a master secret and nonces (random numbers).Step 3: From the master secret, four keys are derived:Two for encryption (one per direction)Two for MAC (Message Authentication Code) to verify integritySecure Data TransferData is divided into records (frames).Each record includes:Length header – defines boundaries between data and MACMAC – ensures integrity and prevents tamperingAdvanced ProtectionsSequence numbers prevent reordering attacks.Type field in MAC prevents truncation attacks, where an attacker might cut off messages prematurely.3. Actual TLS Implementation Cipher SuitesTLS uses cipher suites to define:Public key algorithm (e.g., RSA)Symmetric encryption algorithm (e.g., AES, RC4)Hash algorithm for MAC (e.g., SHA-256)Client proposes supported suites; server chooses the strongest mutually supported one.Four-Step HandshakeNegotiate security capabilitiesServer authenticates itself to the clientOptional client authenticationFinalization – premaster secret and session keys are derived using exchanged random numbersRecord ProtocolEnsures secure data transfer by:Fragmenting the messageCompressing the dataAppending a MACEncrypting the recordAdding a TLS header (content type, version, length) before sending over TCPAnalogyHandshake: Like a secure diplomatic meeting where participants check IDs, agree on a secret language, and synchronize watches.Record Protocol: The actual conversation, where each sentence is translated, numbered, and sealed so the listener can verify order and integrity.You can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:What PGP is and where it operates in the network stackHow PGP secures email confidentiality and authenticityThe three-part structure of a PGP-secured messageHow session keys, public keys, and digital signatures work togetherThe cryptographic algorithms supported by PGPIntroduction Pretty Good Privacy (PGP) is an application-layer security protocol designed to protect email communications. It combines symmetric encryption, public key cryptography, and digital signatures to ensure that messages remain confidential, authentic, and tamper-proof during transmission. How PGP Secures an Email PGP divides a protected email into three main components, each serving a specific security purpose. Part One: Session Key ProtectionContains the session key and the symmetric encryption algorithm usedThe session key is a temporary, randomly generated keyThis entire part is encrypted using the recipient’s public keyEnsures that only the intended recipient can recover the session keyPart Two: Encrypted Content and Digital SignatureContains the actual email messageThe message is encrypted using the session keyIncludes a digital signature created by:Hashing the message to produce a digestEncrypting the digest with the sender’s private keyProvides:Integrity (message was not altered)Authentication (message truly came from the sender)Non-repudiationAlso specifies the hashing and encryption algorithms usedPart Three: PGP HeaderContains protocol-related metadataHelps the recipient’s PGP software correctly process the messageCryptographic Algorithms Supported by PGP PGP is flexible and supports multiple cryptographic standards:Public Key Algorithms:RSADSSHash Functions:MD5SHA-1RIPEMDSymmetric Encryption Algorithms:AESTriple DES (3DES)Key TakeawaysPGP operates at the application layerUses hybrid encryption for efficiency and securityPublic keys protect the session key, not the message directlyDigital signatures ensure authenticity and integrityWidely used for secure email communicationYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:What end point authentication is and why it mattersWhy early authentication methods failedHow replay attacks and spoofing workThe role of nonces in proving “liveness”Why public keys alone are not enoughHow digital certificates solve Man-in-the-Middle attacksIntroduction End point authentication is the process by which one entity proves its identity to another over a network. This lesson traces the evolution of authentication mechanisms, showing how each weak design led to stronger and more secure solutions used on today’s internet. 1. Early Authentication Methods and Their Failures Simple Identification & IP-Based AuthenticationAn entity simply claims an identity, orIdentity is inferred from the source IP addressProblem: Attackers can easily spoof IP addressesResult: No real proof of identityPasswords and Encrypted PasswordsUsers authenticate by sending a password (plain or encrypted)Problem: Vulnerable to replay attacksAn attacker records the authentication packetThe same packet is resent later to gain accessEncryption does not prevent replay2. Nonces and Challenge–Response Authentication What Is a Nonce?A random number used only onceEnsures the communicating party is “live”How It WorksBob sends a nonce to AliceAlice encrypts the nonce using a shared secret keyBob decrypts and verifies the responseStrengthsPrevents replay attacksProves the entity is actively respondingLimitationsRequires a pre-shared secret keyNot scalable for large networks or the internet3. Public Key Authentication and Its Weakness Why Public Keys Were IntroducedRemoves the need for pre-shared secretsAnyone can encrypt data using a public keyThe Major Flaw: Man-in-the-Middle (MITM)An attacker intercepts the communicationSubstitutes their own public keyAlice and Bob each think they are talking directlyAttacker reads and modifies all trafficKey InsightPublic key cryptography alone does not authenticate identity4. The Final Solution: Digital Certificates What Digital Certificates SolveBind a public key to a verified identityPrevent attackers from substituting keys unnoticedRole of Certification Authorities (CAs)Verify identitiesIssue digital certificatesSign certificates using their private keyWhy This Stops MITM AttacksAn attacker cannot forge a valid certificateAny key substitution attempt is detectedTrust is anchored in the CA5. Real-World ImpactThis model is the foundation of HTTPSModern browsers automatically verify certificatesEnd point authentication is now built into everyday internet useKey TakeawaysIdentity claims and IP-based authentication are insecurePasswords alone are vulnerable to replay attacksNonces add freshness but require shared secretsPublic keys enable scalability but are MITM-proneDigital certificates are the only robust solutionTrusted third parties are essential for secure authenticationYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:How data integrity is ensured using cryptographic hash functionsHow MD5 and SHA-1 generate fixed-length message digestsWhy encryption alone does not guarantee identityHow Certification Authorities (CAs) authenticate identities and prevent impersonationIntroduction This lesson explains how secure digital communication relies on two critical pillars beyond encryption: integrity verification and identity authentication. It focuses on the role of hash functions in detecting data tampering and the role of Certification Authorities in establishing trust between communicating parties. 1. Data Integrity with Hash Functions Hash functions transform data of any size into a fixed-length output, known as a message digest. Even a one-bit change in the original message results in a completely different hash value. Key Properties of Hash FunctionsFixed-size output regardless of input sizeOne-way (computationally infeasible to reverse)Highly sensitive to input changesEfficient to computeMD5 (Message Digest 5)Produces a 128-bit hash valueProcesses data through multiple internal transformation roundsDesigned to make it infeasible to reconstruct the original message from the digestUseful historically for integrity checks, though no longer considered secure against collisionsSHA-1 (Secure Hash Algorithm 1)Produces a 160-bit hash valueStandardized by NISTDivides input into 512-bit blocksEach block is processed sequentiallyThe output of one round becomes part of the input to the nextMore robust than MD5, but now considered cryptographically weak for modern security needsWhy Hash Functions MatterDetect unauthorized changes to dataEnsure files and messages arrive unalteredUsed in digital signatures, password storage, and integrity verification2. Identity Authentication with Certification Authorities (CAs) Encryption protects confidentiality, but it does not prove who sent the message. Without authentication, attackers can impersonate legitimate users. The Problem: Impersonation An attacker can:Claim to be someone elseSend their own public key while pretending it belongs to a trusted entityTrick the recipient into trusting malicious communicationThe Solution: Certification Authorities Certification Authorities are trusted third parties that verify identities and bind them to cryptographic keys. What a CA DoesVerifies the identity of an individual or organizationBinds that identity to a public keyIssues a digital certificateSigns the certificate using the CA’s private keyHow Certificates Are UsedThe recipient verifies the certificate using the CA’s public keyThe sender’s authentic public key is extracted from the certificateThis ensures:The message truly came from the claimed senderThe message was not altered in transitHow Integrity and Authentication Work TogetherHash functions detect message modificationDigital certificates confirm sender identityCombined, they prevent:TamperingSpoofingMan-in-the-Middle attacksKey TakeawaysHash functions ensure data integrity, not identityMD5 and SHA-1 produce fixed-length digests from variable-length inputEncryption alone cannot prevent impersonationCertification Authorities establish trust by binding identities to public keysSecure communication requires integrity + authentication + encryptionYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:What asymmetric (public key) cryptography is and why it is neededHow the RSA algorithm works and where it is used in practiceHow Diffie-Hellman enables secure key exchange over public networksWhy asymmetric cryptography is vulnerable without authenticationIntroduction This lesson provides an in-depth explanation of asymmetric key cryptography, focusing on RSA and Diffie-Hellman. These algorithms solve a fundamental problem in network security: how to communicate securely over an insecure channel, such as the internet, without sharing secrets in advance. Asymmetric Cryptography Overview Asymmetric cryptography uses two mathematically related keys:Public key: Shared with everyonePrivate key: Kept secret by the ownerWhat is encrypted with one key can only be decrypted with the other. This model enables secure communication, authentication, and key exchange at scale. 1. RSA (Rivest–Shamir–Adleman) RSA is a general-purpose asymmetric encryption algorithm based on the computational difficulty of factoring very large numbers. Key GenerationTwo large prime numbers are selected: P and QThese are multiplied to produce n = P × QA public key is created: (n, e)A private key is created: (n, d)Knowing n does not make it feasible to derive d without factoring nEncryption and DecryptionThe sender converts the message into a number MEncryption is performed using the public key:C = M^e mod nThe receiver decrypts using the private key:M = C^d mod nOnly the private key holder can reverse the operation. Practical Use of RSARSA operations are slow and computationally expensiveIt is not used to encrypt large dataInstead, RSA is commonly used to:Securely exchange a symmetric session keyAuthenticate servers and usersThe exchanged symmetric key is then used with fast algorithms like AES2. Diffie-Hellman Key Exchange Diffie-Hellman is not an encryption algorithm; it is a key exchange protocol. PurposeAllows two parties to generate a shared symmetric keyNo prior secret is requiredThe shared key is never transmitted over the networkHow It WorksTwo public values are agreed upon:A large prime number PA generator GEach party chooses a private value:Alice chooses XBob chooses YPublic values are exchanged:Alice sends G^X mod PBob sends G^Y mod PBoth compute the same shared secret:G^(XY) mod PEven though all exchanged values are public, the shared secret remains secure. Key PropertiesSecure against passive eavesdroppingEnables perfect forward secrecy when used correctlyWidely used in secure protocols such as TLS3. Man-in-the-Middle (MITM) Vulnerability Both RSA and Diffie-Hellman are mathematically secure, but they are vulnerable at the protocol level if identities are not verified. The AttackAn attacker intercepts the key exchangeEstablishes one secret key with AliceEstablishes a different secret key with BobRelays messages between both sides while decrypting and re-encrypting themBoth parties believe they are communicating securely, but the attacker sees everything. The SolutionAuthentication is mandatoryIdentity verification must occur before or during key exchangeCommon solutions include:Digital certificatesTrusted certificate authoritiesSigned public keysWithout authentication, encryption alone does not guarantee security. Key TakeawaysAsymmetric cryptography solves the secure key distribution problemRSA relies on the difficulty of factoring large numbersRSA is mainly used for key exchange and authentication, not bulk data encryptionDiffie-Hellman enables secure key exchange without sharing secretsBoth systems are vulnerable to MITM attacks without authenticationSecure systems always combine encryption + authenticationYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:How modern cryptography differs from classical ciphersThe building blocks of bit-oriented encryptionHow DES, 3DES, and AES work at a high levelWhy block cipher modes of operation are necessaryIntroduction This lesson provides a structured overview of modern cryptographic techniques, focusing on how today’s encryption systems operate at the bit level, how complex standards like DES and AES are constructed, and how modes of operation securely apply block ciphers to real-world data. Foundational Concepts of Modern Ciphers Modern cryptography is bit-oriented, meaning it works directly on bits rather than characters. This allows encryption of all digital data types, including text, audio, images, and video. Basic Cipher Components Complex modern ciphers are built by combining several simple operations:XOR (Exclusive OR) CipherPerforms a bitwise XOR between data and a keySimple but essential for mixing key material with dataRotation CipherRotates bits left or right with wraparoundHelps spread bit influence across the dataSubstitution Ciphers (S-Boxes)Replace input bits with output bits using lookup tablesVariants include:Equal size substitution (n = m)Expansion (n < m)Compression (n > m)Transposition / Permutation Ciphers (P-Boxes or T-Boxes)Reorder bits based on fixed permutation patternsCan preserve size or perform expansion/reductionIncrease diffusion by spreading bit changesRound Cipher Structure Most modern block ciphers use a round-based design:Encryption is performed over multiple roundsEach round applies substitution, permutation, and XOREach round uses a different subkey derived from a master keySecurity increases with the number and complexity of roundsKey Encryption Standards Data Encryption Standard (DES)Early U.S. encryption standardOperates on 64-bit blocksUses a 56-bit key (stored as 64 bits)Consists of 16 roundsDES Round Function Each round includes:Splitting input into two 32-bit halvesExpansion P-box: 32 → 48 bitsXOR with a 48-bit round keyS-boxes: 48 → 32 bitsStraight permutationFeistel structure swaps halves each roundTriple DES (3DES)Designed to improve DES securityApplies DES three times in an Encrypt–Decrypt–Encrypt sequenceKey options:Two-key version: 112-bit securityThree-key version: 168-bit securityMore secure than DES, but slower and largely deprecatedAdvanced Encryption Standard (AES)Current global encryption standardReplaced DES and 3DESOperates on 128-bit blocksSupports three key sizes:128-bit192-bit256-bitMore rounds are used as key size increasesDesigned for high security and high performanceModes of Operation for Block Ciphers Block ciphers encrypt fixed-size blocks, but real data streams require modes of operation to handle multiple blocks securely. 1. Electronic Code Book (ECB)Each block encrypted independentlyIdentical plaintext blocks → identical ciphertext blocksLeaks patterns and is insecureNot recommended for real-world use2. Cipher Block Chaining (CBC)Each plaintext block is XORed with the previous ciphertextEliminates repeated ciphertext patternsRequires an Initialization Vector (IV)Suffers from error propagation across blocks3. Cipher Feedback (CFB)Converts block cipher into a stream-like cipherSupports encrypting smaller data units (R bits)Uses a shift register with feedback from ciphertextError propagation affects subsequent blocks4. Output Feedback (OFB)Similar to CFB but feeds back encrypted output instead of ciphertextEncryption stream is independent of ciphertextNo error propagationRequires careful IV synchronizationInitialization Vector (IV)Required for CBC, CFB, and OFB modesEnsures uniqueness of the first encryption blockMust be agreed upon by sender and receiverPrevents pattern reuse across messagesKey TakeawaysModern encryption operates at the bit levelStrong ciphers are built from simple operations combined over many roundsDES introduced round-based block encryption but is no longer secure3DES improved security but is inefficientAES is the modern standard due to strength and performanceModes of operation are essential for securely encrypting large or streaming dataECB is insecure, while CBC, CFB, and OFB address pattern leakage in different waysYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:What traditional (classical) ciphers are and why they were usedThe two main categories of traditional encryption techniquesHow substitution ciphers hide informationHow transposition ciphers obscure messages by rearranging charactersIntroduction This lesson introduces traditional ciphers, also known as classical encryption algorithms. These methods were developed long before modern digital communication and cryptography. They protect information by substituting characters or reordering them, making the original message unreadable to unintended recipients. Although insecure by modern standards, traditional ciphers are important for understanding the foundations of cryptography and how encryption concepts evolved. Main Categories of Traditional Ciphers Traditional ciphers are generally divided into two primary categories: 1. Substitution Ciphers Substitution ciphers work by replacing one character or symbol with another according to a defined rule or key. Monoalphabetic CiphersEach plaintext character is always replaced by the same ciphertext character.The substitution does not change based on the character’s position.Example:A → D3 → 7This creates a one-to-one mapping between plaintext and ciphertext characters.Caesar Cipher (Shift Cipher)One of the simplest and most well-known monoalphabetic ciphers.Commonly uses only uppercase alphabetic characters.Encryption shifts each character forward by a fixed number (the key).Example: with a key of 5A → FWhen the shift passes Z, it wraps around to the beginning of the alphabet.Decryption reverses the process by shifting characters backward using the same key.Polyalphabetic CiphersThe substitution depends on the character’s position in the message.A single plaintext character may be replaced by different ciphertext characters at different positions.This creates a one-to-many relationship, making patterns harder to detect.Typically implemented by:Dividing plaintext into groupsApplying a sequence of keys cyclically across the characters2. Transposition Ciphers Transposition ciphers do not replace characters.Instead, they rearrange (permute) the existing characters according to a key. Key CharacteristicsThe original characters remain unchangedOnly their positions are alteredThe encryption process typically involves:Removing spaces from the plaintextDividing the message into blocks based on a keyReordering characters within each blockAdding padding characters if a block is incompleteDecryptionThe receiver uses the same keyThe permutation process is reversedThe original plaintext is reconstructedKey TakeawaysTraditional ciphers are the foundation of modern cryptographySubstitution ciphers hide messages by replacing charactersTransposition ciphers hide messages by rearranging charactersMonoalphabetic ciphers are simple but vulnerable to analysisPolyalphabetic ciphers improve security by reducing patternsUnderstanding classical ciphers helps explain why modern encryption is necessaryYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy

In this lesson, you’ll learn about:The fundamental goals of computer network securityThe four core security properties used to protect network communicationsThe classic security model involving Alice, Bob, and EveCommon threat behaviors observed in insecure communication channelsIntroduction This lesson introduces the foundations of computer network security by explaining its core objectives and the main actors involved in secure and insecure communications. To simplify complex security concepts, a widely used abstract model is employed, featuring Alice, Bob, and Eve. This model helps students understand how legitimate communication works, how it can be attacked, and why security mechanisms are necessary. Core Aspects of Network Security Computer network security focuses on protecting information as it is exchanged between interconnected systems. It is built upon four fundamental aspects: 1. Confidentiality Confidentiality ensures that information remains private.If a sender encrypts a message, only the intended recipient should be able to decrypt and read it.Unauthorized parties should gain no meaningful information, even if they intercept the data.2. Authentication Authentication verifies the identities of communicating parties.Both the sender and receiver must confirm who they are communicating with.This prevents attackers from pretending to be trusted users or systems.3. Message Integrity (Message Authentication) Message integrity ensures that transmitted data has not been altered.The receiver must be able to detect any modification immediately.This protects against tampering, insertion, or deletion of data during transmission.4. Access and Availability Availability ensures that network services remain usable.Legitimate users must be able to access systems and services when needed.Security mechanisms should protect against disruptions that prevent normal operation.The Security Actors: Alice, Bob, and Eve To explain security threats clearly, network security often uses three symbolic characters: Alice and BobRepresent legitimate and trusted entities.They may be real users, applications, network devices, or servers.Their goal is to communicate securely and reliably.Examples include:A user accessing an online banking serviceTwo routers exchanging routing informationA client communicating with a web serverEveRepresents the adversary or intruder.Eve is not a specific person, but a model for any malicious entity attempting to interfere with communication.Common Attacks Performed by Eve Eve can attempt several types of attacks on the communication channel between Alice and Bob: Interception and EavesdroppingEve listens to the communication to obtain confidential information.This violates confidentiality.Message ManipulationEve intercepts messages and modifies their contents.She may delete messages or inject new, fake ones.This breaks message integrity.Man-in-the-Middle (Hijacking)Eve positions herself between Alice and Bob.All communication passes through Eve without their knowledge.Eve can read, modify, or redirect messages freely.Impersonation and SpoofingEve pretends to be Alice when communicating with Bob.Bob believes the messages originate from Alice, even though they do not.This undermines authentication.Denial of Service (DoS) AttacksEve overwhelms Bob with excessive requests.Often combined with spoofing techniques.Bob becomes unable to respond to legitimate requests from Alice.This violates availability.Key Educational TakeawaysNetwork security exists to protect confidentiality, integrity, authentication, and availabilityLegitimate communication must be protected from interception and manipulationAttackers exploit weaknesses in trust, identity, and visibilityThe Alice–Bob–Eve model provides a simple but powerful way to analyze security threatsUnderstanding attacker behavior is essential for designing effective defensesYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy