I'm trying to understand the basics of mining and have a very specific question about hashing a blob. When I start a miner and capture the packets, I get a job from the pool and then the work submitted by the miner.

Job recieved from the pool:

  "jsonrpc": "2.0",
  "result": {
    "job": {
      "blob": "0b0befdeecee051358860383d8e14f3529859e0c2f64c31a631addef3f9ca97eedcc738324fbd9000000009e18d5ad6a814f39bb79c9558f292aea7101e154c114e57c2205732d2e8b7eca02",
      "target": "37894100",
      "job_id": "8241143554386990819",
      "time_to_live": 5,
      "height": 1974336,
      "algo": "cn/r"
    "status": "OK",
    "id": "1177745781301023725"
  "id": 1,
  "error": null

I think that I have classified these right, if not please correct me:

  • Versions: 0b0b
  • Timestamp: efdeecee05
  • Prev Id: 1358860383d8e14f3529859e0c2f64c31a631addef3f9ca97eedcc738324fbd9
  • Nonce: 00000000
  • Transactions Tree Root: 9e18d5ad6a814f39bb79c9558f292aea7101e154c114e57c2205732d2e8b7eca
  • Transaction Count: 02
  • Hashing blob: 0b0befdeecee051358860383d8e14f3529859e0c2f64c31a631addef3f9ca97eedcc738324fbd9000000009e18d5ad6a814f39bb79c9558f292aea7101e154c114e57c2205732d2e8b7eca02

Share that the pool accepted:

  "id": 2,
  "jsonrpc": "2.0",
  "method": "submit",
  "params": {
    "id": "1177745781301023725",
    "job_id": "8241143554386990819",
    "nonce": "41000000",
    "result": "78aeeba968470a2b000c42e46ce60e3e422efbd2fb58fa275384855cd8131d00"

My question boils down to: Where in the blob 0b0befdeecee051358860383d8e14f3529859e0c2f64c31a631addef3f9ca97eedcc738324fbd9000000009e18d5ad6a814f39bb79c9558f292aea7101e154c114e57c2205732d2e8b7eca02 do I need to insert the nonce 41000000 to get the result 78aeeba968470a2b000c42e46ce60e3e422efbd2fb58fa275384855cd8131d00 after feeding the blob through the CryptoNight hashing algorithm?

If my understanding is correct, I need to replace the bytes 00000000 with the 41000000 found nonce, but when I do that, the resulting hash is different from the miner submitted hash.

I'm using a C implementation of CryptoNight and I'm checking the results with an online implementation that I found here.

1 Answer 1


You have the correct location for the nonce bytes. However, are you using the same CryptoNight variant? I doubt this.

The current version (CN/R), also requires a height parameter as input. Therefore we can know for sure the version you linked to is not using CN/R (it is not asking for a height parameter as input). So unless you are mining to an old pool / chain, you can also be pretty certain you are mining CN/R, which explains why your result hash sent to the pool differs from the one using the link.

  • No problem. Easy to overlook.
    – jtgrassie
    Nov 25, 2019 at 22:31

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