hashimoto

	Source (upstream pre-purge)	Current
File	consensus/ethash/algorithm.go	algorithm.go
Symbol	hashimoto	hashimoto
Ref	dde2da0ef~1	etc/v1.17.3-full-node

ADAPT: crypto.Keccak512 removed in #27178, replaced with sha3.NewLegacyKeccak512()

3-way merge — purge → getc ← upstream

pre-purgefork-only

↗// hashimoto aggregates data from the full dataset in order to produce our final

// value for a particular header hash and nonce.

func hashimoto(hash []byte, nonce uint64, size uint64, lookup func(index uint32) []uint32) ([]byte, []byte) {

// Calculate the number of theoretical rows (we use one buffer nonetheless)

rows := uint32(size / mixBytes)

↗ // Combine header+nonce into a 40 byte seed

seed := make([]byte, 40)

copy(seed, hash)

binary.LittleEndian.PutUint64(seed[32:], nonce)

keccak512Hasher := sha3.NewLegacyKeccak512()

keccak512Hasher.Write(seed)

seed = keccak512Hasher.Sum(nil)

↗ seedHead := binary.LittleEndian.Uint32(seed)

↗ // Start the mix with replicated seed

mix := make([]uint32, mixBytes/4)

for i := 0; i < len(mix); i++ {

mix[i] = binary.LittleEndian.Uint32(seed[i%16*4:])

}

// Mix in random dataset nodes

temp := make([]uint32, len(mix))

↗ for i := 0; i < loopAccesses; i++ {

parent := fnv(uint32(i)^seedHead, mix[i%len(mix)]) % rows

for j := uint32(0); j < mixBytes/hashBytes; j++ {

copy(temp[j*hashWords:], lookup(2*parent+j))

}

fnvHash(mix, temp)

}

// Compress mix

for i := 0; i < len(mix); i += 4 {

mix[i/4] = fnv(fnv(fnv(mix[i], mix[i+1]), mix[i+2]), mix[i+3])

}

mix = mix[:len(mix)/4]

↗ digest := make([]byte, common.HashLength)

for i, val := range mix {

binary.LittleEndian.PutUint32(digest[i*4:], val)

}

return digest, crypto.Keccak256(append(seed, digest...))

}

core-geth validation — +3 -1

| | | |---|---| | File | [`algorithm.go`](https://github.com/etclabscore/core-geth/blob/v1.12.20/consensus/ethash/algorithm.go) | | Symbol | `hashimoto` | | Ref | `v1.12.20` |

--- a/core-geth/consensus/ethash/algorithm.go
+++ b/etc/consensus/ethash/algorithm.go
@@ -9,7 +9,9 @@
    copy(seed, hash)
    binary.LittleEndian.PutUint64(seed[32:], nonce)

-   seed = crypto.Keccak512(seed)
+   keccak512Hasher := sha3.NewLegacyKeccak512()
+   keccak512Hasher.Write(seed)
+   seed = keccak512Hasher.Sum(nil)
    seedHead := binary.LittleEndian.Uint32(seed)

    // Start the mix with replicated seed

← Consensus & Ethash