I called bitcoind getwork slightly earlier in the day and this is what I got:

    "midstate" : "6d8b2d759123e7311c552f0c99f6d520378062ac7a14fb11f6d433779d282faf",
    "data" : "00000002c2bf65e9637a1c11955c2ba1c45c9bffad322d4fa0d9529e0000014300000000e9587c30863f5f410ea9d0611d3da6b7d0afd390b4b8e33cd71297c9d20dc74651ad7ea71a01616400000000000000800000000000000000000000000000000000000000000000000000000000000000000000000000000080020000",
    "hash1" : "00000000000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000010000",
    "target" : "0000000000000000000000000000000000000000000000646101000000000000"

So for the time being lets throw away the midstate which I will not be using since I am only trying to understand. So now doing the 32 bit byteswap on the data I get this:

02000000 e965bfc2111c7a63a12b5c95ff9b5cc4 4f2d32ad9e52d9a04301000000000000 307c58e9415f3f8661d0a90eb7a63d1d90d3afd03ce3b8b4c99712d746c70dd2 a77ead51 6461011a 00000000

Now I am unable to figure out how to actually read this information. According to the wiki, the first 4 bytes are version. Here the first 4 bytes are version.


Isnt it supposed to be 2. The above is a really large number in big endian.

Now the previuos hash block:


I am unable to find this hash anywhere on blockexplorer or block chain info? I tried to change the endianess once again but to no avail.

Finally I left the merkle root out and tried to confirm with the utc time:


Which corresponds to the year 2081. What exactly am I doing wrong here?

  • getwork has been pretty much deprecated, you should use getblocktemplate instead.
    – jgm
    Jun 4, 2013 at 8:19

1 Answer 1


Isnt it supposed to be 2. The above is a really large number in big endian.

It's a small number in big endian. Think about it; big digits at the end.

Now the previuos hash block

I don't know why Bitcoin does this, but block hashes are stored in normal order internally, then byte-reversed before displaying them.

>>> s="e965bfc2111c7a63a12b5c95ff9b5cc44f2d32ad9e52d9a04301000000000000"
>>> import binascii
>>> s=binascii.unhexlify(s)
>>> s=s[::-1]
>>> s=binascii.hexlify(s)
>>> s



Use big endian. I got 1370324647 using this tool, then converted to 04 Jun 2013 with this tool.

  • I didnt know I have to do that extra step to get the data. Anyway I think I understand now. Thanks a lot. Just out of curiosity, how did you know this?
    – Enthusiast
    Jun 5, 2013 at 1:43
  • @Enthusiast Reading wiki articles, bitcoin source code, pyminer source code. Also, I started writing a mining client, but I lost interest.
    – Nick ODell
    Jun 5, 2013 at 16:33

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