🧾 1. What Is PEM (Privacy-Enhanced Mail)?
Originally, PEM was a set of IETF standards (from the 1990s) designed to provide:
📧 Confidentiality (encryption of emails)
✅ Authentication (sender verification)
🔐 Integrity (tamper protection)
📜 Key management (using public-key infrastructure)
However, as a secure email standard, PEM was never widely adopted, and modern secure email uses standards like PGP and S/MIME instead.
📂 2. What Is PEM Today? (File Format)
In practice, PEM is now best known for its file format used to store:
SSL/TLS certificates (X.509)
Private keys
Certificate signing requests (CSRs)
Public keys
These files are Base64-encoded with headers and footers like:
PEM file extensions: .pem, .crt, .cer, .key, .csr (often interchangeable, depending on content)
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Originally, PEM was a set of IETF standards (from the 1990s) designed to provide:
📧 Confidentiality (encryption of emails)
✅ Authentication (sender verification)
🔐 Integrity (tamper protection)
📜 Key management (using public-key infrastructure)
However, as a secure email standard, PEM was never widely adopted, and modern secure email uses standards like PGP and S/MIME instead.
📂 2. What Is PEM Today? (File Format)
In practice, PEM is now best known for its file format used to store:
SSL/TLS certificates (X.509)
Private keys
Certificate signing requests (CSRs)
Public keys
These files are Base64-encoded with headers and footers like:
-----BEGIN CERTIFICATE-----
[Base64 encoded data]
-----END CERTIFICATE-----
PEM file extensions: .pem, .crt, .cer, .key, .csr (often interchangeable, depending on content)
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
📚 OS & Hardware — What is DMA (Direct Memory Access)? ⚙️🧵
Let’s explore how computers move data super efficiently without burdening the CPU!
🔹 DMA = Direct Memory Access
🧠 It lets devices talk directly to RAM, skipping the CPU
💥 Makes data transfer much faster & more efficient
🔧 Without DMA:
CPU handles every byte of data → slow + distracting
🔧 With DMA:
CPU gives the job to the DMA controller, then goes back to work.
Once done → DMA sends an interrupt
📦 Used In:
File transfers 📂
Network packets 🌐
GPU / sound systems 🎮
Embedded devices 📷
🍔 Analogy:
DMA = Assistant who moves stuff so the chef (CPU) can focus on cooking!
#OS #DMA #Memory #Interrupts #HardwareAcceleration #InfoSecTube
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Let’s explore how computers move data super efficiently without burdening the CPU!
🔹 DMA = Direct Memory Access
🧠 It lets devices talk directly to RAM, skipping the CPU
💥 Makes data transfer much faster & more efficient
🔧 Without DMA:
CPU handles every byte of data → slow + distracting
🔧 With DMA:
CPU gives the job to the DMA controller, then goes back to work.
Once done → DMA sends an interrupt
📦 Used In:
File transfers 📂
Network packets 🌐
GPU / sound systems 🎮
Embedded devices 📷
🍔 Analogy:
DMA = Assistant who moves stuff so the chef (CPU) can focus on cooking!
#OS #DMA #Memory #Interrupts #HardwareAcceleration #InfoSecTube
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🔐 What Does Forward Secrecy Do?
1)When you establish a secure connection (like HTTPS), the session uses a temporary session key to encrypt data.
2)Forward secrecy ensures that each session key is unique and ephemeral — it’s generated for that session only and not derived solely from the server’s long-term key.
3)If an attacker obtains the server’s private key later on, they cannot decrypt past communications recorded from earlier sessions.
🧠 How Is Forward Secrecy Achieved?
Typically, through ephemeral key exchange algorithms such as:
Ephemeral Diffie-Hellman (DHE)
Elliptic Curve Ephemeral Diffie-Hellman (ECDHE)
These generate a fresh temporary key pair per session.
1)When you establish a secure connection (like HTTPS), the session uses a temporary session key to encrypt data.
2)Forward secrecy ensures that each session key is unique and ephemeral — it’s generated for that session only and not derived solely from the server’s long-term key.
3)If an attacker obtains the server’s private key later on, they cannot decrypt past communications recorded from earlier sessions.
🧠 How Is Forward Secrecy Achieved?
Typically, through ephemeral key exchange algorithms such as:
Ephemeral Diffie-Hellman (DHE)
Elliptic Curve Ephemeral Diffie-Hellman (ECDHE)
These generate a fresh temporary key pair per session.
PGP stands for Pretty Good Privacy, and it is a widely used encryption and digital signing system that provides confidentiality, integrity, and authentication for digital communication—especially emails and files.
🔐 What Does PGP Do?
PGP allows you to:
Encrypt messages/files so only the intended recipient can read them
Digitally sign messages/files to prove they came from you and weren't altered
🧠 How PGP Works (High-Level):
PGP uses a hybrid cryptographic approach:
Asymmetric encryption (public/private keys) for key exchange and digital signatures
Symmetric encryption (e.g., AES) for actual message encryption (faster)
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🔐 What Does PGP Do?
PGP allows you to:
Encrypt messages/files so only the intended recipient can read them
Digitally sign messages/files to prove they came from you and weren't altered
🧠 How PGP Works (High-Level):
PGP uses a hybrid cryptographic approach:
Asymmetric encryption (public/private keys) for key exchange and digital signatures
Symmetric encryption (e.g., AES) for actual message encryption (faster)
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🐞Feature learning, also known as representation learning, is a machine learning technique where a model automatically learns the most relevant features from raw data without manual intervention. Instead of a human "feature engineer" explicitly defining features, the model learns them through training. This process allows the model to discover complex patterns and structures in the data, leading to improved performance in tasks like classification, anomaly detection, and clustering.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
📚 Linux Tip — What is fsck? 💻🧵
Your file system got corrupted after a crash? Time to meet your new best friend: fsck 🔧
🔹 What is it?
fsck = File System Consistency Check
🩺 It scans & fixes file system errors
🧠 Why use it?
Crash recovery 💥
Power failure ⚡️
Dirty shutdowns 🔌
Fix broken file links, bad inodes, orphan blocks
🔧 Basic Usage:
✅ Fix all: fsck -y
🔍 Check only: fsck -n
📌 Unmount first!
🧠 fsck = Disk Doctor for Linux
One command that can save your whole system! 🔥
#Linux #FSCK #FileSystem #DiskRecovery #InfoSecTube
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Your file system got corrupted after a crash? Time to meet your new best friend: fsck 🔧
🔹 What is it?
fsck = File System Consistency Check
🩺 It scans & fixes file system errors
🧠 Why use it?
Crash recovery 💥
Power failure ⚡️
Dirty shutdowns 🔌
Fix broken file links, bad inodes, orphan blocks
🔧 Basic Usage:
sudo fsck /dev/sda1
✅ Fix all: fsck -y
🔍 Check only: fsck -n
📌 Unmount first!
umount /dev/sda1
🧠 fsck = Disk Doctor for Linux
One command that can save your whole system! 🔥
#Linux #FSCK #FileSystem #DiskRecovery #InfoSecTube
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🧬 Process Data Structures
OS keeps a process list (or task list)
Each entry is a Process Control Block (PCB) or struct proc
Contains:
Memory info
Register context (for context switch)
Process ID
State
Parent pointer
Open files
Other runtime data
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
OS keeps a process list (or task list)
Each entry is a Process Control Block (PCB) or struct proc
Contains:
Memory info
Register context (for context switch)
Process ID
State
Parent pointer
Open files
Other runtime data
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🧠 Core Idea
How can an OS create, control, and manage processes?
UNIX uses three key system calls to do this:
fork() — Create a new process
exec() — Replace the process’s memory with a new program
wait() — Wait for a child process to finish
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
How can an OS create, control, and manage processes?
UNIX uses three key system calls to do this:
fork() — Create a new process
exec() — Replace the process’s memory with a new program
wait() — Wait for a child process to finish
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🍩A "hub-and-spoke" CA model in Public Key Infrastructure (PKI) is a hierarchical structure where a central authority, the "hub," acts as the root CA, and multiple subordinate authorities, the "spokes," act as issuing CAs. This model distributes the workload and responsibility for issuing certificates, improving scalability and security.
Here's a more detailed breakdown:
🔥Root CA (Hub):
The top-level CA, trusted by all entities in the PKI. It's responsible for issuing certificates to the issuing CAs (spokes).
🔰Issuing CAs (Spokes):
These CAs are subordinate to the Root CA and are responsible for issuing certificates to end entities (users, devices, servers).
🧊End Entities:
The entities that use the certificates issued by the issuing CAs (spokes).
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Here's a more detailed breakdown:
🔥Root CA (Hub):
The top-level CA, trusted by all entities in the PKI. It's responsible for issuing certificates to the issuing CAs (spokes).
🔰Issuing CAs (Spokes):
These CAs are subordinate to the Root CA and are responsible for issuing certificates to end entities (users, devices, servers).
🧊End Entities:
The entities that use the certificates issued by the issuing CAs (spokes).
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🕸 DNS Rebinding: When the Browser Turns Against You
Imagine inviting someone into your house, and they quietly unlock a door to your private network.
That’s DNS rebinding — where the attacker tricks your browser into attacking your own LAN. 🧠🏠
🧠 What Is DNS Rebinding?
DNS rebinding is a technique that allows attackers to bypass browser security and interact with internal resources (like 192.168.x.x) by abusing how DNS works.
It turns the browser into a proxy, rebinding a domain name to a different IP — often a private one.
📘 “DNS rebinding attacks subvert the browser’s same-origin policy by making a trusted domain resolve to a local IP after initial connection.”
🔍 How It Works:
Victim visits attacker.com
The DNS server returns a public IP (so the browser allows connection)
After the page loads, the DNS record is updated (rebinding) to a private IP, like 127.0.0.1 or 192.168.1.1
Browser still trusts it — because it's from the “same origin”
Scripts from attacker.com now access your router, printer, or internal APIs 😱
🧪 Real-World Impact:
Steal sensitive data from internal dashboards
Change router DNS settings
Exploit vulnerable IoT devices on your LAN
Attack services not exposed to the internet
🛡 Defenses:
🔒 Block private IP responses on DNS resolvers (e.g., dnsmasq or cloud firewalls)
🛑 Use browser protections (modern browsers limit DNS rebinding by default)
⚙️ Disable Web access to local admin interfaces when possible
🔍 Monitor DNS behavior and HTTP requests for anomalies
📌 Fun Fact:
Even Google Home and routers have been attacked using DNS rebinding in real-world exploits.
🧩 TL;DR
DNS rebinding is like social engineering for browsers — it tricks your machine into attacking itself or your local network.
Same domain, different IP, total compromise.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Imagine inviting someone into your house, and they quietly unlock a door to your private network.
That’s DNS rebinding — where the attacker tricks your browser into attacking your own LAN. 🧠🏠
🧠 What Is DNS Rebinding?
DNS rebinding is a technique that allows attackers to bypass browser security and interact with internal resources (like 192.168.x.x) by abusing how DNS works.
It turns the browser into a proxy, rebinding a domain name to a different IP — often a private one.
📘 “DNS rebinding attacks subvert the browser’s same-origin policy by making a trusted domain resolve to a local IP after initial connection.”
🔍 How It Works:
Victim visits attacker.com
The DNS server returns a public IP (so the browser allows connection)
After the page loads, the DNS record is updated (rebinding) to a private IP, like 127.0.0.1 or 192.168.1.1
Browser still trusts it — because it's from the “same origin”
Scripts from attacker.com now access your router, printer, or internal APIs 😱
🧪 Real-World Impact:
Steal sensitive data from internal dashboards
Change router DNS settings
Exploit vulnerable IoT devices on your LAN
Attack services not exposed to the internet
🛡 Defenses:
🔒 Block private IP responses on DNS resolvers (e.g., dnsmasq or cloud firewalls)
🛑 Use browser protections (modern browsers limit DNS rebinding by default)
⚙️ Disable Web access to local admin interfaces when possible
🔍 Monitor DNS behavior and HTTP requests for anomalies
📌 Fun Fact:
Even Google Home and routers have been attacked using DNS rebinding in real-world exploits.
🧩 TL;DR
DNS rebinding is like social engineering for browsers — it tricks your machine into attacking itself or your local network.
Same domain, different IP, total compromise.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
📁 What Is a Directory, Really?
In the OS world, a directory isn’t magic — it’s just a special file that holds tuples:
🧾 (name, i-number) — a mapping from a human-readable name to a file or directory’s low-level ID.
🔍 What’s Inside a Directory?
Each entry can point to:
A file (e.g., report.pdf → inode 1024)
Another directory (e.g., projects/ → inode 2048)
Even the directory itself has its own i-number!
📘 The OS doesn’t care about file names — only i-numbers (inode numbers).
The directory just maps human names → actual files via these numbers.
🔗 Special Entries You’ll Always Find:
. → refers to itself
.. → refers to its parent directory
These are essential for navigating the file system (e.g., cd .. to go up a level).
🧪 Example — Inside a folder called /home/user:
🧩 TL;DR
A directory is just a list of (name, i-number) pairs that map names to files or subdirectories — including itself (.) and its parent (..).
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
In the OS world, a directory isn’t magic — it’s just a special file that holds tuples:
🧾 (name, i-number) — a mapping from a human-readable name to a file or directory’s low-level ID.
🔍 What’s Inside a Directory?
Each entry can point to:
A file (e.g., report.pdf → inode 1024)
Another directory (e.g., projects/ → inode 2048)
Even the directory itself has its own i-number!
📘 The OS doesn’t care about file names — only i-numbers (inode numbers).
The directory just maps human names → actual files via these numbers.
🔗 Special Entries You’ll Always Find:
. → refers to itself
.. → refers to its parent directory
These are essential for navigating the file system (e.g., cd .. to go up a level).
🧪 Example — Inside a folder called /home/user:
. → i-number 4567 (this directory)
.. → i-number 2345 (its parent)
notes → i-number 6789 (a file)
docs → i-number 8910 (a sub-directory)
🧩 TL;DR
A directory is just a list of (name, i-number) pairs that map names to files or subdirectories — including itself (.) and its parent (..).
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
💞A Program Dependence Graph (PDG) is a representation of a program's control and data dependencies, using a directed graph. Nodes in the PDG represent program statements, and edges represent the relationships between those statements, showing how one statement might affect the execution of another. These dependencies are crucial for compiler optimization and analysis.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
📚 OS Concepts — Scheduling Algorithms Compared! 🧵
How does your OS decide which app runs next? Let’s compare the 4 big ones in simple terms:
🔹 1. FIFO (First-In, First-Out)
🛒 Run in the order they arrive
😐 Simple, but if a long job comes first... everyone waits!
🔹 2. SJF (Shortest Job First)
⏳ Runs the shortest task first
✅ Great for efficiency
❌ Bad for long tasks — they may never run
🔹 3. STCF (Shortest Time to Completion First)
🧠 Smarter version of SJF — but preemptive
🔁 Always picks the job with the least time left
📈 Good response time, but needs to know job lengths!
🔹 4. Round Robin
🔄 Every task gets a turn!
🕒 Each process runs for a fixed time slice (quantum)
✅ Fair for all, great for multitasking
❌ May have overhead from frequent switching
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
How does your OS decide which app runs next? Let’s compare the 4 big ones in simple terms:
🔹 1. FIFO (First-In, First-Out)
🛒 Run in the order they arrive
😐 Simple, but if a long job comes first... everyone waits!
🔹 2. SJF (Shortest Job First)
⏳ Runs the shortest task first
✅ Great for efficiency
❌ Bad for long tasks — they may never run
🔹 3. STCF (Shortest Time to Completion First)
🧠 Smarter version of SJF — but preemptive
🔁 Always picks the job with the least time left
📈 Good response time, but needs to know job lengths!
🔹 4. Round Robin
🔄 Every task gets a turn!
🕒 Each process runs for a fixed time slice (quantum)
✅ Fair for all, great for multitasking
❌ May have overhead from frequent switching
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🎯 What Can Be Done via Syscall Hijacking?
1) Hide files, processes, or network connections
2) Escalate privileges
3) Bypass security checks
4) Intercept credentials or sensitive data
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
1) Hide files, processes, or network connections
2) Escalate privileges
3) Bypass security checks
4) Intercept credentials or sensitive data
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🧠 1. Soft Updates (SU)
🔍 What is it?
Soft Updates are a technique to maintain on-disk consistency without using journaling.
Instead of logging changes, the system orders metadata writes carefully so that the disk is always in a consistent state, even after a crash.
✅ Key Idea:
💡 If a file is deleted, don't free its blocks until the inode is updated.
💡 If a file is created, update the directory only after writing the inode.
📌 Benefit:
Faster than journaling
Reduces redundant writes
Ensures metadata correctness
❗️Downside:
Complex implementation
Doesn’t protect file data, only metadata
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🔍 What is it?
Soft Updates are a technique to maintain on-disk consistency without using journaling.
Instead of logging changes, the system orders metadata writes carefully so that the disk is always in a consistent state, even after a crash.
✅ Key Idea:
💡 If a file is deleted, don't free its blocks until the inode is updated.
💡 If a file is created, update the directory only after writing the inode.
📌 Benefit:
Faster than journaling
Reduces redundant writes
Ensures metadata correctness
❗️Downside:
Complex implementation
Doesn’t protect file data, only metadata
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🧠 What’s the Thompson Compiler Backdoor?
Ken Thompson (co-creator of Unix) showed how a compiler itself can be modified to insert a backdoor — without that backdoor appearing in any source code.
🧪 How It Works:
1️⃣ Modify the compiler to recognize when it's compiling login and inject a backdoor (e.g., accept a secret password)
2️⃣ ALSO modify the compiler to recognize when it’s compiling itself — and reinject the malicious behavior
3️⃣ Result: Even if someone recompiles the compiler from clean source, the backdoor reappears automatically!
😱 So the source code can look 100% clean… but the compiled output is still malicious.
🛑 Why It’s Scary:
Completely invisible in source audits
Infects every binary built with the backdoored compiler
Trust becomes recursive: You must trust the thing that builds the thing
🛡 Modern Relevance & Mitigations:
✅ Reproducible builds — verify binaries match the source
✅ Bootstrapping from trusted roots
✅ Open-source compiler ecosystems with verifiable toolchains
Ken’s lesson?
“You can’t trust code you did not totally create yourself.”
A timeless reminder in the age of supply chain attacks.
#CyberSecurity #CompilerBackdoor #KenThompson #TrustingTrust #SupplyChainSecurity #Backdoors #InfoSec #HackingHistory #SecureCoding #OpenSourceTrust
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Ken Thompson (co-creator of Unix) showed how a compiler itself can be modified to insert a backdoor — without that backdoor appearing in any source code.
🧪 How It Works:
1️⃣ Modify the compiler to recognize when it's compiling login and inject a backdoor (e.g., accept a secret password)
2️⃣ ALSO modify the compiler to recognize when it’s compiling itself — and reinject the malicious behavior
3️⃣ Result: Even if someone recompiles the compiler from clean source, the backdoor reappears automatically!
😱 So the source code can look 100% clean… but the compiled output is still malicious.
🛑 Why It’s Scary:
Completely invisible in source audits
Infects every binary built with the backdoored compiler
Trust becomes recursive: You must trust the thing that builds the thing
🛡 Modern Relevance & Mitigations:
✅ Reproducible builds — verify binaries match the source
✅ Bootstrapping from trusted roots
✅ Open-source compiler ecosystems with verifiable toolchains
Ken’s lesson?
“You can’t trust code you did not totally create yourself.”
A timeless reminder in the age of supply chain attacks.
#CyberSecurity #CompilerBackdoor #KenThompson #TrustingTrust #SupplyChainSecurity #Backdoors #InfoSec #HackingHistory #SecureCoding #OpenSourceTrust
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
📚 OS Concepts — Inode vs Superblock Explained! 🧵
Ever wonder how your OS keeps track of files & the whole disk? Let’s break down inode vs superblock 👇
🔹 Inode = File Metadata
📁 One inode per file/dir
✅ Stores:
Size, owner, permissions
Timestamps
Pointers to file data blocks
❌ Does NOT store the file name!
🔹 Superblock = File System Metadata
💽 One per file system
✅ Stores:
File system type (ext4, etc.)
Total/free blocks & inodes
Block size
Mount info
🧠 Analogy:
🧾 Inode = Info about 1 document
📚 Superblock = Table of contents of the entire filing cabinet
📌 TL;DR:
Inode = per file
Superblock = per file system
#OS #Inode #Superblock #FileSystem #StorageManagement #InfoSecTube
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
Ever wonder how your OS keeps track of files & the whole disk? Let’s break down inode vs superblock 👇
🔹 Inode = File Metadata
📁 One inode per file/dir
✅ Stores:
Size, owner, permissions
Timestamps
Pointers to file data blocks
❌ Does NOT store the file name!
🔹 Superblock = File System Metadata
💽 One per file system
✅ Stores:
File system type (ext4, etc.)
Total/free blocks & inodes
Block size
Mount info
🧠 Analogy:
🧾 Inode = Info about 1 document
📚 Superblock = Table of contents of the entire filing cabinet
📌 TL;DR:
Inode = per file
Superblock = per file system
#OS #Inode #Superblock #FileSystem #StorageManagement #InfoSecTube
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
💮a NOP slide is a sequence of NOP (no-operation) instructions that is inserted at the beginning of a code section. When a program branches to the start of this code section, it will "slide" through the NOP instructions until it reaches the desired, final destination. This technique is commonly used in software exploits to direct program execution when the target of a branch instruction is not known precisely.
💉For example, suppose an attacker has found a buffer overflow vulnerability in a program and wants to exploit it to execute arbitrary code. They might insert a NOP slide at the start of the buffer, followed by the code they want to execute. When the program overflows the buffer and branches to the start of the buffer, it will slide through the NOP instructions until it reaches the attacker's code, which will then be executed.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
💉For example, suppose an attacker has found a buffer overflow vulnerability in a program and wants to exploit it to execute arbitrary code. They might insert a NOP slide at the start of the buffer, followed by the code they want to execute. When the program overflows the buffer and branches to the start of the buffer, it will slide through the NOP instructions until it reaches the attacker's code, which will then be executed.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🦚S/MIME stands for Secure/Multipurpose Internet Mail Extensions. It is a widely adopted email encryption and digital signing standard used primarily in corporate and government environments.
📧 What Does S/MIME Do?
S/MIME provides two main security features for email:
🔐 Encryption – Ensures that only the intended recipient can read the message
✍️ Digital Signature – Verifies the identity of the sender and ensures message integrity
🧠 How S/MIME Works
S/MIME uses X.509 digital certificates and public key cryptography:
You have a public-private key pair
Your S/MIME certificate includes your public key, issued by a trusted Certificate Authority (CA)
✅ Sending a Signed Email:
You sign the email with your private key
The recipient verifies the signature using your public key from your S/MIME certificate
✅ Sending an Encrypted Email:
You encrypt the message using the recipient’s public key
Only the recipient can decrypt it using their private key
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
📧 What Does S/MIME Do?
S/MIME provides two main security features for email:
🔐 Encryption – Ensures that only the intended recipient can read the message
✍️ Digital Signature – Verifies the identity of the sender and ensures message integrity
🧠 How S/MIME Works
S/MIME uses X.509 digital certificates and public key cryptography:
You have a public-private key pair
Your S/MIME certificate includes your public key, issued by a trusted Certificate Authority (CA)
✅ Sending a Signed Email:
You sign the email with your private key
The recipient verifies the signature using your public key from your S/MIME certificate
✅ Sending an Encrypted Email:
You encrypt the message using the recipient’s public key
Only the recipient can decrypt it using their private key
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🔴 تکنیکهای پیشرفته کشسازی در معماری سیستمها
🔸 افزایش سرعت دسترسی به دادهها، در بسیاری از سیستمها به کمک حافظه کش (Cache) امکانپذیر شده است. اما پیادهسازی دقیق و مؤثر کش، به دانش تخصصیتری نیاز دارد.
🔹 کش میتواند در لایههای مختلفی مثل CPU، دیسک، شبکه یا حتی سمت سرورهای API پیادهسازی شود. برای مثال، در طراحی وبسرویسها، استفاده از Redis یا Memcached به عنوان حافظه کش خارجی، بار روی دیتابیس را کاهش داده و سرعت پاسخ را افزایش میدهد. الگوهایی مانند Cache-aside، Write-through و Write-back برای مدیریت دادههای کش بسیار مهم هستند. همچنین، تعیین زمان انقضا (TTL) و invalidate کردن کش هنگام تغییر دادهها، از چالشهای اصلی محسوب میشود.
⭕️ درک عمیق از معماری کش، یکی از ارکان طراحی سیستمهای مقیاسپذیر و پرسرعت است.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us
🔸 افزایش سرعت دسترسی به دادهها، در بسیاری از سیستمها به کمک حافظه کش (Cache) امکانپذیر شده است. اما پیادهسازی دقیق و مؤثر کش، به دانش تخصصیتری نیاز دارد.
🔹 کش میتواند در لایههای مختلفی مثل CPU، دیسک، شبکه یا حتی سمت سرورهای API پیادهسازی شود. برای مثال، در طراحی وبسرویسها، استفاده از Redis یا Memcached به عنوان حافظه کش خارجی، بار روی دیتابیس را کاهش داده و سرعت پاسخ را افزایش میدهد. الگوهایی مانند Cache-aside، Write-through و Write-back برای مدیریت دادههای کش بسیار مهم هستند. همچنین، تعیین زمان انقضا (TTL) و invalidate کردن کش هنگام تغییر دادهها، از چالشهای اصلی محسوب میشود.
⭕️ درک عمیق از معماری کش، یکی از ارکان طراحی سیستمهای مقیاسپذیر و پرسرعت است.
🎯@InfoSecTube
📌YouTube channel
🎁Boost Us