Postmark[ The post office for crypto ]
0BLK
Robinhood ChainReading the latest block
Postmark [ The post office for crypto ] BLK Robinhood Chain · connecting $MARKCA at launch

Call it now.Prove itlater.

[ Sealed calls, Robinhood Chain ]

CT runs onscreenshots.

[ Tweets delete. Blocks don't. ]

Write it.Seal it.Nobodyreads it.

[ 32 bytes, 0 words ]

The chainstampsthe time.

[ 0.10 s per block, live ]

Open itwhen ithits.

[ 1 hash, 1 answer ]

Don't trustour RPCeither.

[ 64 headers, re-hashed locally ]

$MARKlauncheson pons.

[ one billion · one locked pool ]

Call it now.

Prove it later.

The chain keeps the time.

( Lab 01 )Verify

Check the clock before you trust it.

Everything here runs in this tab. The hash function first proves itself against published test vectors. Then the page pulls the last 64 blocks from the public RPC, rebuilds every header byte by byte, hashes it and checks each block points at the one before. Last, it corrupts one header on purpose, so you see what a lie looks like.

re-hash suite (runs in your browser)idle
Keccak-256 known-answer vectors, RLP examples from the Ethereum spec, then 64 live headers from Robinhood Chain rebuilt and re-hashed here. Press run.

What this proves: each hash really is the hash of its header, and the 64 headers form one unbroken chain. What it does not prove: that the sequencer ordered transactions fairly. Robinhood Chain runs a single sequencer.

( Lab 02 )Seal a call

Your call never leaves this page.

Type the call. The page makes a random key, hashes both into a seal and shows you the key. Post the seal with your wallet: a zero ETH transaction to yourself on Robinhood Chain, gas a fraction of a cent. The block it lands in is your postmark.

Nothing sealed yet.

Keep the key. Without it nobody can ever open the seal, you included. We never see it; this browser keeps a copy only so you can find it again.

( Lab 03 )Open a seal

Anyone can check. Nobody has to trust.

Paste the transaction, the call and the key. Your browser fetches the transaction from Robinhood Chain, recomputes the seal, re-hashes the header of the block the time comes from, and gives one answer.

Nothing opened yet.

A seal proves when a call was made, not that it was the only one. An address can seal both sides and open only the winner. Before you believe a caller, open their address on the explorer and count their seals.

( Lab 04 )Code

No private source. This page is the app.

These tabs print the functions running on this page, read from the page itself when it loads. There is no backend, no contract of ours and no key that signs anything for you.

chainRobinhood Chain · ID 4663
rpcrpc.mainnet.chain.robinhood.com
seal data0x504d4b31 ("PMK1") + 32-byte seal
ticker$MARK
contractat launch
treasuryat launch