sendcurrency

What it is

sendcurrency is a Verus RPC call that sends value — but it can also attach arbitrary data to the transaction. When the daemon is running with -enablefileencryption and the destination is a shielded z-address, the attached data is encrypted automatically. The format is data: { filename: "image.png" }, and the file contents (up to ~1 MB) are included in the shielded transaction output.

To read the encrypted data, you need the z-address's extended viewing key (EVK). The Sapling EVK reveals all incoming notes to that address — which is exactly why the curator uses a single-purpose z-address that only ever held these 7 deliveries. Publishing the EVK leaks the contents of those 7 transactions and nothing else.

The decryption call is decryptdata, which takes the encrypted objectdata and the EVK and returns the original plaintext bytes. The viewer does this live — every image you see is decrypted from the blockchain in real time via the whitelisted endpoint at rpc.vrsc.syncproof.net.

Why it matters

This is cryptographic proof of delivery. The encrypted bytes are on chain, the viewing key is published, and anyone can run decryptdata to recover the original file. Then they SHA-256 the result and compare against the on-chain image-datahash that the curator signed. If the hashes match, the delivery is proven: the file the curator sent is exactly the file the curator signed.

The pattern generalises. Healthcare records where a patient publishes a scoped viewing key to their doctor. Legal documents delivered with cryptographic proof of content. Evidence chains where the delivery itself is independently verifiable. Any scenario where "I sent you exactly this file" needs to be provable to third parties.