path: root/ethchain/dagger.go

package ethchain

import (
    "github.com/ethereum/eth-go/ethutil"
    "github.com/obscuren/sha3"
    "hash"
    "log"
    "math/big"
    "math/rand"
    "time"
)

type PoW interface {
    Search(block *Block) []byte
    Verify(hash []byte, diff *big.Int, nonce []byte) bool
}

type EasyPow struct {
    hash *big.Int
}

func (pow *EasyPow) Search(block *Block) []byte {
    r := rand.New(rand.NewSource(time.Now().UnixNano()))

    hash := block.HashNoNonce()
    diff := block.Difficulty
    for {
        sha := ethutil.Sha3Bin(big.NewInt(r.Int63()).Bytes())
        if pow.Verify(hash, diff, sha) {
            return sha
        }
    }

    return nil
}

func (pow *EasyPow) Verify(hash []byte, diff *big.Int, nonce []byte) bool {
    sha := sha3.NewKeccak256()

    d := append(hash, nonce...)
    sha.Write(d)

    v := ethutil.BigPow(2, 256)
    ret := new(big.Int).Div(v, diff)

    res := new(big.Int)
    res.SetBytes(sha.Sum(nil))

    return res.Cmp(ret) == -1
}

func (pow *EasyPow) SetHash(hash *big.Int) {
}

type Dagger struct {
    hash *big.Int
    xn   *big.Int
}

var Found bool

func (dag *Dagger) Find(obj *big.Int, resChan chan int64) {
    r := rand.New(rand.NewSource(time.Now().UnixNano()))

    for i := 0; i < 1000; i++ {
        rnd := r.Int63()

        res := dag.Eval(big.NewInt(rnd))
        log.Printf("rnd %v\nres %v\nobj %v\n", rnd, res, obj)
        if res.Cmp(obj) < 0 {
            // Post back result on the channel
            resChan <- rnd
            // Notify other threads we've found a valid nonce
            Found = true
        }

        // Break out if found
        if Found {
            break
        }
    }

    resChan <- 0
}

func (dag *Dagger) Search(hash, diff *big.Int) *big.Int {
    // TODO fix multi threading. Somehow it results in the wrong nonce
    amountOfRoutines := 1

    dag.hash = hash

    obj := ethutil.BigPow(2, 256)
    obj = obj.Div(obj, diff)

    Found = false
    resChan := make(chan int64, 3)
    var res int64

    for k := 0; k < amountOfRoutines; k++ {
        go dag.Find(obj, resChan)
    }

    // Wait for each go routine to finish
    for k := 0; k < amountOfRoutines; k++ {
        // Get the result from the channel. 0 = quit
        if r := <-resChan; r != 0 {
            res = r
        }
    }

    return big.NewInt(res)
}

func (dag *Dagger) Verify(hash, diff, nonce *big.Int) bool {
    dag.hash = hash

    obj := ethutil.BigPow(2, 256)
    obj = obj.Div(obj, diff)

    return dag.Eval(nonce).Cmp(obj) < 0
}

func DaggerVerify(hash, diff, nonce *big.Int) bool {
    dagger := &Dagger{}
    dagger.hash = hash

    obj := ethutil.BigPow(2, 256)
    obj = obj.Div(obj, diff)

    return dagger.Eval(nonce).Cmp(obj) < 0
}

func (dag *Dagger) Node(L uint64, i uint64) *big.Int {
    if L == i {
        return dag.hash
    }

    var m *big.Int
    if L == 9 {
        m = big.NewInt(16)
    } else {
        m = big.NewInt(3)
    }

    sha := sha3.NewKeccak256()
    sha.Reset()
    d := sha3.NewKeccak256()
    b := new(big.Int)
    ret := new(big.Int)

    for k := 0; k < int(m.Uint64()); k++ {
        d.Reset()
        d.Write(dag.hash.Bytes())
        d.Write(dag.xn.Bytes())
        d.Write(big.NewInt(int64(L)).Bytes())
        d.Write(big.NewInt(int64(i)).Bytes())
        d.Write(big.NewInt(int64(k)).Bytes())

        b.SetBytes(Sum(d))
        pk := b.Uint64() & ((1 << ((L - 1) * 3)) - 1)
        sha.Write(dag.Node(L-1, pk).Bytes())
    }

    ret.SetBytes(Sum(sha))

    return ret
}

func Sum(sha hash.Hash) []byte {
    //in := make([]byte, 32)
    return sha.Sum(nil)
}

func (dag *Dagger) Eval(N *big.Int) *big.Int {
    pow := ethutil.BigPow(2, 26)
    dag.xn = pow.Div(N, pow)

    sha := sha3.NewKeccak256()
    sha.Reset()
    ret := new(big.Int)

    for k := 0; k < 4; k++ {
        d := sha3.NewKeccak256()
        b := new(big.Int)

        d.Reset()
        d.Write(dag.hash.Bytes())
        d.Write(dag.xn.Bytes())
        d.Write(N.Bytes())
        d.Write(big.NewInt(int64(k)).Bytes())

        b.SetBytes(Sum(d))
        pk := (b.Uint64() & 0x1ffffff)

        sha.Write(dag.Node(9, pk).Bytes())
    }

    return ret.SetBytes(Sum(sha))
}