1 files changed, 199 insertions, 0 deletions
diff --git a/ethchain/dagger.go b/ethchain/dagger.go
new file mode 100644
index 000000000..5b4f8b2cd
--- /dev/null
+++ b/ethchain/dagger.go
@@ -0,0 +1,199 @@
+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))
+}