55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
// Copyright (c) 2017-2026 Lethean (https://lt.hn)
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//
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// Licensed under the European Union Public Licence (EUPL) version 1.2.
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// SPDX-License-Identifier: EUPL-1.2
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package consensus
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import (
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"encoding/binary"
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"math/big"
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"forge.lthn.ai/core/go-blockchain/crypto"
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"forge.lthn.ai/core/go-blockchain/types"
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)
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// maxTarget is 2^256, used for difficulty comparison.
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var maxTarget = new(big.Int).Lsh(big.NewInt(1), 256)
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// CheckDifficulty returns true if hash meets the given difficulty target.
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// The hash (interpreted as a 256-bit little-endian number) must be less
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// than maxTarget / difficulty.
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func CheckDifficulty(hash types.Hash, difficulty uint64) bool {
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if difficulty == 0 {
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return true
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}
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// Convert hash to big.Int (little-endian as per CryptoNote convention).
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// Reverse to big-endian for big.Int.
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var be [32]byte
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for i := range 32 {
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be[i] = hash[31-i]
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}
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hashInt := new(big.Int).SetBytes(be[:])
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target := new(big.Int).Div(maxTarget, new(big.Int).SetUint64(difficulty))
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return hashInt.Cmp(target) < 0
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}
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// CheckPoWHash computes the RandomX hash of a block header hash + nonce
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// and checks it against the difficulty target.
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func CheckPoWHash(headerHash types.Hash, nonce, difficulty uint64) (bool, error) {
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// Build input: header_hash (32 bytes) || nonce (8 bytes LE).
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var input [40]byte
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copy(input[:32], headerHash[:])
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binary.LittleEndian.PutUint64(input[32:], nonce)
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key := []byte("LetheanRandomXv1")
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powHash, err := crypto.RandomXHash(key, input[:])
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if err != nil {
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return false, err
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}
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return CheckDifficulty(types.Hash(powHash), difficulty), nil
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}
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