How to use it
- 1. Read the chainFarm → processor → port → vessel → DC → retailer. Every block stores its payload, its hash and the previous hash.
- 2. TamperEdit any field. The edited block and every block after it turn red - the links no longer verify.
- 3. Re-mine to hide itRe-mine the broken blocks one by one, in order, and watch the attempt counter climb.
- 4. CompareThe plain database on the right takes the same edit silently. That difference is the whole lesson.
The custody chain
mining attempts: 0
Same shipment, central database
Edit anything here - nothing turns red, nothing counts attempts, and no one can later prove the record changed. The contrast with the chain is the lesson.
Try these experiments
- Fake the temperature at the Port block and count how many blocks break (it and everything downstream).
- Re-mine to hide it at difficulty 3 and note the total attempts - roughly 4,096 per block on average.
- From the counter, explain why consortium chains run low difficulty: trusted validators replace brute-force cost.
About this tool
The concept
A blockchain is tamper-evident, not tamper-proof: any edit invalidates every later hash, so hiding a change means rewriting the whole tail of the chain.
How it works
Each block's SHA-256 hash covers its payload, a nonce and the previous hash. Proof-of-work demands hashes with leading zeros - found only by brute force.
In supply chains
Custody records (temperature, weight, handler, time) become verifiable across firms that don't fully trust each other - the classic cold-chain use case.