I was messing around on the blockchain learning about OP_RETURN outputs and the equivalent use of Input Data in Ethereum and came across something interesting and I can't make sense of it.

It starts with a ETH transaction:


When decoded, the input data mentions a Bitcoin address:


When I looked at this Bitcoin address I noticed the following transaction:


Based on the timing and values in the ETH and BTC transactions I figured this was some kind of coin exchange (they were swapping ETH for BTC) which I thought was rather neat as I never thought of using OP_RETURN in this way. But then I noticed that in the Bitcoin transaction above we have another OP_RETURN output which decodes to:

OUT:D304E780755F46E62A42884421E39AF06342F0A4989704EE02989043769C4F93 <-- there is a space on the end

First I thought this might be a Doge Coin address as it starts with "D" but it is too long and now my curiosity has the better of me. Does anyone know what that D304... might be?


1 Answer 1


The decoded OP_RETURN output


matches the transaction identifier of the Ethereum transaction you mention first

  • Don't know how I didn't see that. I got so hung up on it being a hex encoding and trying to decode it. Commented Jan 18 at 3:48

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