Blockchain-Secured Communication Network

Network

Peer nodes 6

Sender node

Message text

Tamper Test

Block to tamper

Ledger Status

Chain length

Verified peers

0 / 6

Integrity

VALID ✓

How it works

Each block bundles a message with the SHA-256 hash of the previous block, so it forms a tamper-evident hash chain:

H(block_i) = SHA256(
  H(block_i-1) + sender_id +
  message + timestamp )

Every peer independently recomputes H(block_i) and checks it matches the prevHash stored in block i+1. Change even one character in an old message and its hash changes — every block after it now points to a prevHash that no longer exists, so the chain is flagged invalid from that point forward. This is the core "data integrity" guarantee blockchains give a communication network: no central server needs to be trusted, because any node can verify the whole history itself.

Privacy/authenticity works the same decentralized way. When the network starts, every peer registers a public identity hash in the genesis block — a miniature on-chain PKI (public-key registry). A valid block must carry the sender's registered identity hash. "Simulate Spoofing Attack" broadcasts a message claiming to come from a peer but signed with a forged identity hash; because it doesn't match the value peers stored at genesis, the network rejects it before it ever joins the ledger — exactly how blockchain-anchored identity stops impersonation in a decentralized messaging system.

Valid block Broken / rejected Peer node

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