mining pools – Stratum protocol – problem with implementation in python

For a couple of days I’m trying to write simple script in python to communicate with stratum pool server. I’m using simplified code of NightMiner (https://github.com/ricmoo/nightminer/) and some testnet I’ve foud ( stratum+tcp://pool.bitcoincloud.net:4008), but I can’t get the proper result. Maybe someone more experienced could help me. Below I show each step of my script (step, no python source code).

1. connect to the server, authorize, get the job data

After connecting to the server I send this requests:

b'{"id": 1, "method": "mining.subscribe", "params": []}\n'
b'{"params": ["testuser", "anything"], "id": 2, "method": "mining.authorize"}\n'

and get the following response:

{"id":1,"result":[[["mining.set_difficulty","deadbeefcafebabea200000000000000"],["mining.notify","deadbeefcafebabea200000000000000"]],"40000004",4],"error":null}
{"id":null,"method":"mining.set_difficulty","params":[0.01]}
{"id":null,"method":"mining.notify","params":["4ca","4128bf630f57387b00e25b419d1bb77e667e4036a7d8fee80000015600000000","01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff2503a77614048c8a145e08","122f626974636f696e636c6f75642e6e65742f0000000002062c9c04000000001976a91423e020eacd64acfe093150331d44fdbcc0c7ce0688acc2eb0b00000000001976a91400bf6d61c2a34df5a9ea338fcad188c31bb4a52388ac00000000",[],"20000000","1a02b098","5e148a8c",true]}

2. get the coinbase and merkle root

With this data and extranounce=”00000000″ I can build the coinbase (in byte form, but I will show as hex in this example):

coinbase=coinb1+extranounce1+extranounce2+coinb2
coinbase=b'01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff2503a77614048c8a145e084000000400000000122f626974636f696e636c6f75642e6e65742f0000000002062c9c04000000001976a91423e020eacd64acfe093150331d44fdbcc0c7ce0688acc2eb0b00000000001976a91400bf6d61c2a34df5a9ea338fcad188c31bb4a52388ac00000000'

Next thing to do is double hash the coinbase with SHA256 algo, which gives as the following bytes:

b'9b9c9ab0b1c92844e4fed3f895f9443fefcda5ae02cc5a8ad4444f9303081a23'

There is no merkle branches (merkle branches array is empty), so hash above is our merkle root.

3. building the header

With merkle root and data received in step 1, I can start building a header:

header= version + prevhash + merkle root + ntime + nbits + nonce

I use the values as follows:

version - received '20000000', after little-endian conversion it is '00000020'
prevhash - received '4128bf630f57387b00e25b419d1bb77e667e4036a7d8fee80000015600000000', after conversion it is '63bf28417b38570f415be2007eb71b9d36407e66e8fed8a75601000000000000' (reverse bytes order every 4 bytes)
merkle root - get '9b9c9ab0b1c92844e4fed3f895f9443fefcda5ae02cc5a8ad4444f9303081a23' in step 2, stays that way
ntime - received '5e148a8c', after conversion it is '8c8a145e'
nbits - received '1a02b098', after conversion it is '98b0021a'

So the header is

b'0000002063bf28417b38570f415be2007eb71b9d36407e66e8fed8a756010000000000009b9c9ab0b1c92844e4fed3f895f9443fefcda5ae02cc5a8ad4444f9303081a238c8a145e98b0021a' + nonce

4. search nonce

the difficulty is 0.01, so my target is

00000063ff9c0000000000000000000000000000000000000000000000000000

after some calculations, I find this 4 bytes to use it as a nonce:

b'd0cf1040'

so my complete header is now

b'0000002063bf28417b38570f415be2007eb71b9d36407e66e8fed8a756010000000000009b9c9ab0b1c92844e4fed3f895f9443fefcda5ae02cc5a8ad4444f9303081a238c8a145e98b0021ad0cf1040'

after double-hashing it with SHA256 algo and reverse bytes order I get this hash:

000000032f201567fc4d02fa468bf2dc6a5c21ae70098c124e99ee7d2520ca26

which is below my target, so ‘d0cf1040’ should be the correct nonce.

5. submit nounce

last thing to do is submitting the results, so I send this request to the server:

b'{"id":2, "method":"mining.submit","params":["testuser","4ca","00000000","5e148a8c","d0cf1040"]}\n'

and this is response I get:

{"id":2,"result":false,"error":null}

I have no idea why I get result=false. I can only suppose there is a mistake in step 3 (building header) and this mistake is related to byte-order of some values, but I can’t find this mistake (I have tried many variants of byte-order, but never get the response result=true).

I will be much obliged if anyone can check this calculations and give me some tips.