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ChainRefreshing HeightRefreshing WalletTemporarily unavailable ExplorerRefreshing wHOBC—
Announcement Official Record is live on-chain — Scrypt mining planned next

Published

HobbyHash Coin now publishes an Official Record — an append-only public ledger of project statements sealed with SHA-256 and anchored on the HOBC chain with one OP_RETURN transaction per seal (prefix HOBCOR1 + content hash).

• Browse the Official Record: https://hobbyhashcoin.com/official-record/

Tri-PoW (SHA256d + KawPow + RandomX) remains live. Scrypt is planned work and is not active yet.

— HobbyHash Coin
Developer protocol

On-chain payment messages

HOBCMSG1 lets wallets attach a UTF-8 message to a payment using one OP_RETURN output. Web Wallet messages are public — anyone can read them on the explorer.

Overview

Web Wallet send supports an optional message (max 300 characters). The same wire format is published so Windows, Linux, Android, and third-party apps can implement compatible send/receive.

Public by design

Payment amount, addresses, time, and the message text are all public on-chain. Do not put secrets, passwords, seed phrases, or private personal data in a payment message.

Wire format (public)

Single OP_RETURN data payload used by HobbyHash Web Wallet:

HOBCMSG1 | ver:1 | flags:0 | utf8_plaintext

Prefix ASCII HOBCMSG1, then ver (1 byte, currently 1), flags (1 byte; bit0 = 0 for public plaintext), then UTF-8 message bytes.

Encrypted mode (optional / legacy)

Apps may set flags bit0 = 1 and use secp256k1 ECDH + HKDF-SHA256 + AES-256-GCM to the recipient payment pubkey. HobbyHash Web Wallet currently sends public messages only (flags = 0).

Limits

HobbyHash wallets use a 300-character UTF-8 limit for payment memos. The node relay policy allows larger OP_RETURN data carriers; keep app payloads fee-aware.

Recipient public key

Not required for public messages. Encrypted mode (flags bit0 = 1) requires a compressed payment pubkey that hash160-matches the destination hobc1… address.

RPC example

Build a payment plus data output (hex is the HOBCMSG1 payload), then fund/sign/broadcast — or use the experimental send RPC when available:

hobbyhash-cli -rpcwallet=WALLET send '{"hobc1q…": 1.5, "data": "484f42434d534731…"}'

# Or raw construction:
hobbyhash-cli createrawtransaction '[]' '[{"hobc1q…":1.5},{"data":"484f42434d534731…"}]'
hobbyhash-cli -rpcwallet=WALLET fundrawtransaction HEX
hobbyhash-cli -rpcwallet=WALLET signrawtransactionwithwallet FUNDED_HEX
hobbyhash-cli sendrawtransaction SIGNED_HEX

For app developers

Implement encode/decode against this document. Detect HOBCMSG1 in explorers: show the UTF-8 text when flags bit0 = 0, or an encrypted-message badge when bit0 = 1. Desktop and mobile HobbyHash wallets can reuse this format.

Warning: Web Wallet payment messages are public. Never put secrets in OP_RETURN.