Beginner Track 01
Like a fingerprint — a unique “digital fingerprint” for every piece of data
No matter what data you put in, you always get a unique code of fixed length. Change even a single character and you get a completely different code.
What you’ll learn in this module
- → Exactly what a hash function (SHA-256) is
- → Why even a tiny change in input produces a completely different output
- → How blockchain instantly detects tampering
What is SHA-256?
SHA-256 is a type of hash function. No matter how long the input, it always outputs a fixed 64-character code. Bitcoin uses this function to guarantee data integrity.
Input
“안녕하세요”
SHA-256 hash result
3e5e7a2b...
Input
“안녕하세요!”
SHA-256 hash result
f8c3d921...
Input
“블록체인”
SHA-256 hash result
a1b2c3d4...
💡 Why does this matter for blockchain?
Every block contains the hash of the previous block. Change any past data and all subsequent hashes change in a cascade, so tampering is instantly detected.