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[N3] Proof of node #4304

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cbc8ce8
Proof of node
shargon Nov 11, 2025
7b73285
Fix pow
shargon Nov 11, 2025
58778c3
Ensure Primary it's alive
shargon Nov 12, 2025
de06e7b
Max Proof Of Node Height in policy
shargon Nov 12, 2025
75b2bc7
Set difficulty by policy
shargon Nov 13, 2025
1140f19
Update src/Neo/SmartContract/Native/PolicyContract.cs
shargon Nov 13, 2025
0d2a56f
Remove extra blank line
shargon Nov 13, 2025
841ba47
Add comment
shargon Nov 13, 2025
6738aa7
Pow in separate class
shargon Nov 13, 2025
fe20a2e
Remove null
shargon Nov 13, 2025
c34ab6c
Reduce difficulty
shargon Nov 22, 2025
829f58e
Update src/Neo/Cryptography/ProofOfWork.cs
shargon Nov 22, 2025
35ca4e2
fix
shargon Nov 22, 2025
a938a2b
Merge branch 'proof-of-node' of https://github.com/shargon/neo into p…
shargon Nov 22, 2025
9cdbeec
Merge branch 'master-n3' into proof-of-node
ajara87 Nov 30, 2025
b3a5248
Fix conflicts
ajara87 Nov 30, 2025
1f96009
Merge pull request #18 from ajara87/pr-4304
shargon Nov 30, 2025
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80 changes: 72 additions & 8 deletions src/Neo/SmartContract/Native/NeoToken.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,10 @@

#pragma warning disable IDE0051

using Neo.Cryptography;
using Neo.Cryptography.ECC;
using Neo.Extensions;
using Neo.Network.P2P.Payloads;
using Neo.Persistence;
using Neo.SmartContract.Iterators;
using Neo.SmartContract.Manifest;
Expand Down Expand Up @@ -399,6 +401,46 @@ private bool RegisterCandidate(ApplicationEngine engine, ECPoint pubkey)
return RegisterInternal(engine, pubkey);
}

/// <summary>
/// Proof of life of a candidate.
/// </summary>
/// <param name="engine">The engine used to check witness and read data.</param>
/// <param name="pubkey">The public key of the candidate.</param>
/// <param name="proofOfWork">Proof of Work</param>
/// <param name="blockIndex">Block Index</param>
[ContractMethod(Hardfork.HF_Faun, RequiredCallFlags = CallFlags.States)]
private void ProofOfLife(ApplicationEngine engine, ECPoint pubkey, UInt256 proofOfWork, uint blockIndex)
{
if (engine.PersistingBlock == null || blockIndex >= engine.PersistingBlock.Index)
throw new Exception("Invalid proof of work");

if (!engine.CheckWitnessInternal(Contract.CreateSignatureRedeemScript(pubkey).ToScriptHash()))
throw new Exception("Invalid witness");

var key = CreateStorageKey(Prefix_Candidate, pubkey);
var item = engine.SnapshotCache.GetAndChange(key, () => new StorageItem(new CandidateState()));
var state = item.GetInteroperable<CandidateState>();
if (!state.Registered)
throw new Exception("Only registered candidates are availables");

if (proofOfWork.ToString().StartsWith("0x0000")) // TODO: Decide the proper value
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@roman-khimov roman-khimov Nov 11, 2025

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Why do we need a proof of work at all here? What does it prove?

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@vncoelho vncoelho Nov 11, 2025

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I believe it is for all committee , not only CN

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@shargon shargon Nov 11, 2025

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Cn could be set every time he is the primary

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@shargon shargon Nov 11, 2025

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Why do we need a proof of work at all here? What does it prove?

Proof that the committee has a node

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@roman-khimov roman-khimov Nov 11, 2025

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Well, this doesn't prove there is a node. I can separate this code from the node. My point is that a transaction is sufficient. Adding any calculations would be a serious regression for Neo and it wouldn't add any benefit.

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@shargon shargon Nov 23, 2025

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I also think we don't need to introduce proof of work.

What's your proposal? Regular tx is easy to fake. I thought an idea but it's incompatible with huge amount of committee (outside 21).

If committee produce a signature of the previous block, the primary can choose this rpc signatures and use them as a proof when they persist the block.

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@vncoelho vncoelho Nov 23, 2025

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@shargon @erikzhang , do you know? Double speakers would be perfect for that because we could, every round, make a committee to be a speaker and do round robin on that.

So, every member would need to be ready. Double speakers do that without any problems because they would be fallback. Based on node's statistics we would know the truth.

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@shargon shargon Nov 23, 2025

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That's only work for 21, no for outside 21

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@erikzhang erikzhang Nov 25, 2025

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I believe that if a node deliberately pretends to be online while refusing to participate in the consensus process, there is essentially no reliable way for us to detect such behavior. Therefore, the primary purpose of “proof of node” should not be to identify malicious non-participation. Instead, it should focus on preventing accidental misconfigurations by candidates—such as forgetting to run the node, failing to start the consensus module, or unintentionally launching multiple consensus instances.

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@shargon shargon Nov 25, 2025

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Then only a tx is good for you, and maybe a counter of how many view changes?

throw new Exception("Proof of work is too easy");

if (ComputeProofOfLife(engine.SnapshotCache, blockIndex, (engine.ScriptContainer as Transaction)?.Nonce) != proofOfWork)
throw new Exception("Invalid proof of work");

state.LastProofOfLife = blockIndex;
}

private static UInt256 ComputeProofOfLife(DataCache snapshotCache, uint blockIndex, long? nonce = 0)
{
var blockHash = Ledger.GetBlockHash(snapshotCache, blockIndex);

return blockHash == null
? throw new Exception("Invalid blockIndex")
: (UInt256)Cryptography.Helper.Blake2b_256(blockHash.ToArray(), BitConverter.GetBytes(nonce ?? 0));
}

private bool RegisterInternal(ApplicationEngine engine, ECPoint pubkey)
{
if (!engine.CheckWitnessInternal(Contract.CreateSignatureRedeemScript(pubkey).ToScriptHash()))
Expand Down Expand Up @@ -509,7 +551,7 @@ private async ContractTask<bool> Vote(ApplicationEngine engine, UInt160 account,
[ContractMethod(CpuFee = 1 << 22, RequiredCallFlags = CallFlags.ReadStates)]
internal (ECPoint PublicKey, BigInteger Votes)[] GetCandidates(DataCache snapshot)
{
return GetCandidatesInternal(snapshot)
return GetCandidatesInternal(snapshot, true)
.Select(p => (p.PublicKey, p.State.Votes))
.Take(256)
.ToArray();
Expand All @@ -524,18 +566,20 @@ private async ContractTask<bool> Vote(ApplicationEngine engine, UInt160 account,
private IIterator GetAllCandidates(IReadOnlyStore snapshot)
{
const FindOptions options = FindOptions.RemovePrefix | FindOptions.DeserializeValues | FindOptions.PickField1;
var enumerator = GetCandidatesInternal(snapshot)
var enumerator = GetCandidatesInternal(snapshot, true)
.Select(p => (p.Key, p.Value))
.GetEnumerator();
return new StorageIterator(enumerator, 1, options);
}

internal IEnumerable<(StorageKey Key, StorageItem Value, ECPoint PublicKey, CandidateState State)> GetCandidatesInternal(IReadOnlyStore snapshot)
internal IEnumerable<(StorageKey Key, StorageItem Value, ECPoint PublicKey, CandidateState State)> GetCandidatesInternal(IReadOnlyStore snapshot, bool withProofOfLife)
{
var requiredProofOfLife = Ledger.CurrentIndex(snapshot) - 10_000; // TODO: Decide the proper value
var prefixKey = CreateStorageKey(Prefix_Candidate);

return snapshot.Find(prefixKey)
.Select(p => (p.Key, p.Value, PublicKey: p.Key.Key[1..].AsSerializable<ECPoint>(), State: p.Value.GetInteroperable<CandidateState>()))
.Where(p => p.State.Registered)
.Where(p => p.State.Registered && (!withProofOfLife || (p.State.LastProofOfLife != null && p.State.LastProofOfLife >= requiredProofOfLife)))
.Where(p => !Policy.IsBlocked(snapshot, Contract.CreateSignatureRedeemScript(p.PublicKey).ToScriptHash()));
}

Expand Down Expand Up @@ -607,11 +651,20 @@ public ECPoint[] ComputeNextBlockValidators(DataCache snapshot, ProtocolSettings

private IEnumerable<(ECPoint PublicKey, BigInteger Votes)> ComputeCommitteeMembers(DataCache snapshot, ProtocolSettings settings)
{
decimal votersCount = (decimal)(BigInteger)snapshot[_votersCount];
decimal voterTurnout = votersCount / (decimal)TotalAmount;
var candidates = GetCandidatesInternal(snapshot)
var votersCount = (decimal)(BigInteger)snapshot[_votersCount];
var voterTurnout = votersCount / (decimal)TotalAmount;
var candidates = GetCandidatesInternal(snapshot, true)
.Select(p => (p.PublicKey, p.State.Votes))
.ToArray();

if (candidates.Length < settings.CommitteeMembersCount)
{
// If there are not enough candidates, include those without proof of life
candidates = GetCandidatesInternal(snapshot, false)
.Select(p => (p.PublicKey, p.State.Votes))
.ToArray();
}

if (voterTurnout < EffectiveVoterTurnout || candidates.Length < settings.CommitteeMembersCount)
return settings.StandbyCommittee.Select(p => (p, candidates.FirstOrDefault(k => k.PublicKey.Equals(p)).Votes));
return candidates
Expand Down Expand Up @@ -686,16 +739,27 @@ internal class CandidateState : IInteroperable
{
public bool Registered;
public BigInteger Votes;
public uint? LastProofOfLife;

public void FromStackItem(StackItem stackItem)
{
Struct @struct = (Struct)stackItem;
var @struct = (Struct)stackItem;
Registered = @struct[0].GetBoolean();
Votes = @struct[1].GetInteger();

if (@struct.Count > 2)
{
LastProofOfLife = (uint)@struct[2].GetInteger();
}
}

public StackItem ToStackItem(IReferenceCounter? referenceCounter)
{
if (LastProofOfLife.HasValue)
{
return new Struct(referenceCounter) { Registered, Votes, LastProofOfLife.Value };
}

return new Struct(referenceCounter) { Registered, Votes };
}
}
Expand Down
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