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slide 6 · fundamentals
Immutability
block 1
0000a…
block 2
0001a…
block 3
0002a…
block 4
0003a…
Tamper with a block and watch every after it break — then try to re-mine.
- 1Edit the text inside a block
- 2Watch every later hash break
- 3Try to re-mine the chain
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Difficulty target
hash starts 000
Blocks
0
Chain status
broken
The chain — try editing any block's data
Change a single character and the block's SHA-256 hash changes completely, so it no longer meets the difficulty target — and because the next block stores that hash as its prev, every later block breaks too. Real immutability is not a lock; it is the cost of redoing all that work faster than the honest network, forever.