surkar.in / learn

learn.

Notes, visualizations, and interactive explainers on things I find worth understanding deeply.

001
HMAC-SHA256
How Hash-based Message Authentication Codes work — step-by-step with live computation, XOR visualizations, and real intermediate values.
Cryptography →
002
Base64 Encoding
How 3 bytes become 4 characters — triplet-by-triplet bit visualization, the full alphabet, padding, and URL-safe variant explained.
Cryptography →
003
Jira Workflow Management
Deep dive: issue hierarchy, workflow state machines, the 4 pillars of transitions (conditions, validators, screens, post-functions), roles, boards, and JQL — with an interactive transition simulator.
Infra →
004
gzip & DEFLATE
How gzip works under the hood — LZ77 back-references, Huffman coding, the gzip file format, HTTP compression, performance trade-offs, and an interactive LZ77→Huffman→CRC32 pipeline demo.
Networking →
005
CS Fundamentals
36-topic deep-dive for senior engineers — CPU, OS, networking, TCP, TLS, databases, distributed systems, caching, Kubernetes, observability, algorithms, and more. Each topic has theory + diagrams + a quiz.
Systems →