Hello, I am trying to understand the details about the getwork function and what it returns. When I call getwork, this is an example of what I get from my bitcoin deamon.

./bitcoind getwork

{

"midstate" : "34c2cc4192d802888d2204188e80df8133ddbb17fd0db5ea1382096916f35369",

"data" : "000000013cb5d00bd73e716c2d3c558a52b8c79fe8532b12307a7d91000008ba0000000007b7757adedda569a66c17a870bce5135faa2b3e5f46d22bed6e15d79296178f4ded6d461a1d932f00000000000000800000000000000000000000000000000000000000000000000000000000000000000000000000000080020000",

"hash1" : "00000000000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000010000",

"target" : "00000000000000000000000000000000000000000000002f931d000000000000"

}

I understand how to do hashing since I have just completed a basic c++ implementation. What I do not understand is midstate, data and hash1. Why is the midstate supplied? Isn't it the job of the miner to calculate the hash. If so, why does the deamon waste cycle computing the hash for the first half of the data?

The data. Is it already stuffed and precomputed for hashing? It seems that I must do sha256(sha256(data)). I am not sure if the data has been appended a 1 at the end, then zeros, along with the message length.

What is hash1 and what do I use it for?