Cryptography

Cryptographic concepts and implementations

Systems & Architecture

Cryptocurrency Fundamentals: A Technical Overview
ByEric Ma Jan 15, 2025Apr 12, 2026

Cryptocurrency is a digital currency secured through cryptography and typically operating on decentralized blockchain networks. Unlike government-issued fiat currencies, cryptocurrencies derive their security and validation from distributed consensus mechanisms rather than central authorities. From Speculation to Real-World Infrastructure Early cryptocurrency adoption was primarily speculative. By 2026, the market has matured into genuine utility across multiple…

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Systems & Architecture

TPM 2.0: Understanding Platform Configuration Registers
ByEric Ma Dec 14, 2024Apr 12, 2026

The Trusted Platform Module (TPM) 2.0 is a cryptographic coprocessor—either as discrete hardware or firmware—that provides hardware-rooted security. It’s the foundation for features like Windows Hello, BitLocker, macOS FileVault, and Linux dm-crypt integration with hardware key binding. On modern systems, TPM 2.0 is nearly universal: integrated into recent Intel (PTT), AMD (fTPM), and ARM processors,…

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Systems & Architecture

Understanding PGP: A Technical Reference Guide
ByEric Ma Sep 8, 2024Apr 12, 2026

PGP combines symmetric and asymmetric encryption to achieve both speed and security: Symmetric Encryption: The message itself is encrypted using a random session key with an algorithm like AES-256. This is computationally fast for large files. Asymmetric Encryption: The session key is then encrypted with the recipient’s public key using RSA or ECC. Only the…

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Security & Encryption

Extracting EC Public Keys from Certificates with OpenSSL
ByEric Ma Aug 23, 2024Apr 12, 2026

Verification: You need the public key to verify digital signatures (e.g., in Bitcoin or TLS). Sharing: Public keys are meant to be shared, while the private key must remain secret. Conversion: Sometimes you need to convert a private key file into a public-only certificate for a web server or blockchain application. System Integration: Many tools…

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Systems & Architecture

Understanding Multisig Wallets
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Multisig (multisignature) is a cryptographic mechanism that requires multiple private keys to authorize a blockchain transaction. Think of it as a vault requiring two or more keys to open — no single key holder can move funds alone. How It Works A multisig wallet uses an m-of-n formula, where m is the number of signatures…

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Systems & Architecture

Understanding Sybil Attacks: A Technical Guide
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

A Sybil attack occurs when a single adversary creates many fake identities or nodes to gain disproportionate influence over a network. The name comes from the book and film “Sybil,” about a woman with dissociative identity disorder. In networking and distributed systems, it describes the same concept: one actor pretending to be many. Think of…

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Systems & Architecture

Understanding Byzantine Fault Tolerance
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

A Byzantine Fault occurs when a component in a distributed system behaves unpredictably or maliciously—sending contradictory information to different parts of the system, corrupting data, or deviating entirely from the protocol. The result is potential inconsistency across the network, making consensus impossible without proper safeguards. The term originates from the Byzantine Generals Problem, a thought…

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Systems & Architecture

WebDAV Basics: File Sharing Over HTTP
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

WebDAV (Web-based Distributed Authoring and Versioning) is an HTTP extension that lets you manage files on remote servers over the web. It’s built on HTTP/1.1, so it works through standard web infrastructure—firewalls, proxies, load balancers—without special configuration. Think of it as a bridge between simple HTTP file serving and full-featured version control. You get file…

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Systems & Architecture

Understanding Blockchain Consensus Mechanisms
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

In distributed systems like blockchains, consensus is the mechanism by which all nodes agree on a single version of the ledger state. Without it, a decentralized network falls apart—you’d have conflicting transaction histories, double-spending, and no way to determine which version is authoritative. Consensus algorithms solve this by providing cryptographic or economic guarantees that make…

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Systems & Architecture

Understanding Double-Spending Attacks in Blockchain
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Double-spending is the fundamental vulnerability of digital currency: unlike physical cash, digital information can be copied. If you send me a digital file, I have it and you still have it. Money can’t work that way. Without a mechanism to prevent spending the same unit twice, the entire system collapses into worthlessness. Blockchains exist, at…

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Systems & Architecture

Understanding 51% Attacks in Blockchain
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

A 51% attack happens when an entity or coalition controls more than 50% of a blockchain network’s total hash rate (in Proof-of-Work systems) or stake (in Proof-of-Stake systems). With this majority control, the attacker can: Reverse recent transactions — spend coins, then revert the transaction to regain them Block legitimate transactions — prevent certain addresses…

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Systems & Architecture

Understanding Proof of Work: A Technical Guide
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Proof of Work is the consensus mechanism that secures Bitcoin and a handful of other major blockchain networks. Introduced by Satoshi Nakamoto in 2009, it requires network participants (miners) to solve computationally expensive cryptographic puzzles. The first miner to solve the puzzle earns the right to add the next block of transactions and receives a…

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Systems & Architecture

Understanding Proof of Stake: A Beginner’s Guide
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Proof of Stake is a consensus mechanism that secures blockchain networks by having validators lock up cryptocurrency as collateral. Instead of the energy-intensive mining required by Proof of Work, PoS creates economic incentives: validators earn rewards for honest participation, and lose staked funds if they misbehave or go offline. This “slashing” mechanism makes attacking the…

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Systems & Architecture

Getting Started with Uniswap: A Developer’s Guide
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Uniswap is the largest Decentralized Exchange (DEX) in crypto, built on a fundamentally different model than traditional trading venues. Instead of maintaining an order book where buyers and sellers match trades, it uses an Automated Market Maker (AMM) — a smart contract that determines prices algorithmically based on liquidity pools. The Liquidity Pool Model Rather…

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Systems & Architecture

Getting Started With Ethereum: A Developer’s Guide
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Ethereum is a decentralized, open-source blockchain platform enabling developers to build and deploy smart contracts and decentralized applications (dApps). Launched in 2015 by Vitalik Buterin, it functions as a global computational network—code executes exactly as programmed without downtime, censorship, or third-party interference. Key Milestones 2013: Vitalik Buterin publishes the Ethereum Whitepaper 2014: Public crowdsale raises…

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Systems & Architecture

CalDAV and CardDAV: A Developer’s Guide
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

CalDAV and CardDAV are open, internet-based standards for syncing calendar and contact data across different devices and services. They’re built on WebDAV and the iCalendar/vCard formats, making them vendor-agnostic and suitable for both personal deployments and enterprise environments. What CalDAV Does CalDAV handles calendar synchronization—events, tasks, reminders, and availability data. Add an event on your…

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Systems & Architecture

Building Decentralized Systems: Core Concepts and Design Patterns
ByEthan Ainsworth Sep 16, 2023Apr 12, 2026

Decentralization is the transfer of control and decision-making from a centralized entity—typically a company, government, or institution—to a distributed network of participants. In practice, this means no single actor can unilaterally control the system, change its rules, or shut it down. The Three Dimensions of Decentralization When evaluating whether a system is actually decentralized, consider…

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Systems & Architecture

Cryptographic Tokens: A Developer’s Guide
ByDavid Yang Sep 16, 2023Apr 13, 2026

A cryptographic token is a digital asset issued on top of an existing blockchain. While Bitcoin is the native coin of its own chain, tokens like USDC or Chainlink (LINK) typically run on other chains such as Ethereum or Solana. Tokens are created through smart contracts and represent value, ownership, or access rights—all verifiable and…

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Systems & Architecture

Understanding NFTs: A Beginner’s Guide
ByDavid Yang Sep 16, 2023Apr 12, 2026

A Non-Fungible Token (NFT) is a unique digital certificate stored on a blockchain. Unlike cryptocurrencies like Bitcoin (which are “fungible,” meaning one Bitcoin is identical to another), every NFT has a unique identifier that distinguishes it from all others. Think of it like a signed baseball card or a deed to a house. You can…

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Systems & Architecture

Understanding Cryptographic Hash Functions
ByTony Sep 16, 2023Apr 12, 2026

A cryptographic hash function is a mathematical algorithm that takes any input—a file, password, transaction, or string of any length—and produces a fixed-length output called a “hash” or “digest.” The output is always the same size regardless of input size. SHA-256, for example, always produces a 256-bit (64 hexadecimal character) output. Core Properties Deterministic The…

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