github.com/jonasnick/go-ethereum@v0.7.12-0.20150216215225-22176f05d387/pow/dagger/dagger.go (about)

     1  package dagger
     2  
     3  import (
     4  	"hash"
     5  	"math/big"
     6  	"math/rand"
     7  	"time"
     8  
     9  	"github.com/jonasnick/go-ethereum/crypto/sha3"
    10  	"github.com/jonasnick/go-ethereum/ethutil"
    11  	"github.com/jonasnick/go-ethereum/logger"
    12  )
    13  
    14  var powlogger = logger.NewLogger("POW")
    15  
    16  type Dagger struct {
    17  	hash *big.Int
    18  	xn   *big.Int
    19  }
    20  
    21  var Found bool
    22  
    23  func (dag *Dagger) Find(obj *big.Int, resChan chan int64) {
    24  	r := rand.New(rand.NewSource(time.Now().UnixNano()))
    25  
    26  	for i := 0; i < 1000; i++ {
    27  		rnd := r.Int63()
    28  
    29  		res := dag.Eval(big.NewInt(rnd))
    30  		powlogger.Infof("rnd %v\nres %v\nobj %v\n", rnd, res, obj)
    31  		if res.Cmp(obj) < 0 {
    32  			// Post back result on the channel
    33  			resChan <- rnd
    34  			// Notify other threads we've found a valid nonce
    35  			Found = true
    36  		}
    37  
    38  		// Break out if found
    39  		if Found {
    40  			break
    41  		}
    42  	}
    43  
    44  	resChan <- 0
    45  }
    46  
    47  func (dag *Dagger) Search(hash, diff *big.Int) *big.Int {
    48  	// TODO fix multi threading. Somehow it results in the wrong nonce
    49  	amountOfRoutines := 1
    50  
    51  	dag.hash = hash
    52  
    53  	obj := ethutil.BigPow(2, 256)
    54  	obj = obj.Div(obj, diff)
    55  
    56  	Found = false
    57  	resChan := make(chan int64, 3)
    58  	var res int64
    59  
    60  	for k := 0; k < amountOfRoutines; k++ {
    61  		go dag.Find(obj, resChan)
    62  
    63  		// Wait for each go routine to finish
    64  	}
    65  	for k := 0; k < amountOfRoutines; k++ {
    66  		// Get the result from the channel. 0 = quit
    67  		if r := <-resChan; r != 0 {
    68  			res = r
    69  		}
    70  	}
    71  
    72  	return big.NewInt(res)
    73  }
    74  
    75  func (dag *Dagger) Verify(hash, diff, nonce *big.Int) bool {
    76  	dag.hash = hash
    77  
    78  	obj := ethutil.BigPow(2, 256)
    79  	obj = obj.Div(obj, diff)
    80  
    81  	return dag.Eval(nonce).Cmp(obj) < 0
    82  }
    83  
    84  func DaggerVerify(hash, diff, nonce *big.Int) bool {
    85  	dagger := &Dagger{}
    86  	dagger.hash = hash
    87  
    88  	obj := ethutil.BigPow(2, 256)
    89  	obj = obj.Div(obj, diff)
    90  
    91  	return dagger.Eval(nonce).Cmp(obj) < 0
    92  }
    93  
    94  func (dag *Dagger) Node(L uint64, i uint64) *big.Int {
    95  	if L == i {
    96  		return dag.hash
    97  	}
    98  
    99  	var m *big.Int
   100  	if L == 9 {
   101  		m = big.NewInt(16)
   102  	} else {
   103  		m = big.NewInt(3)
   104  	}
   105  
   106  	sha := sha3.NewKeccak256()
   107  	sha.Reset()
   108  	d := sha3.NewKeccak256()
   109  	b := new(big.Int)
   110  	ret := new(big.Int)
   111  
   112  	for k := 0; k < int(m.Uint64()); k++ {
   113  		d.Reset()
   114  		d.Write(dag.hash.Bytes())
   115  		d.Write(dag.xn.Bytes())
   116  		d.Write(big.NewInt(int64(L)).Bytes())
   117  		d.Write(big.NewInt(int64(i)).Bytes())
   118  		d.Write(big.NewInt(int64(k)).Bytes())
   119  
   120  		b.SetBytes(Sum(d))
   121  		pk := b.Uint64() & ((1 << ((L - 1) * 3)) - 1)
   122  		sha.Write(dag.Node(L-1, pk).Bytes())
   123  	}
   124  
   125  	ret.SetBytes(Sum(sha))
   126  
   127  	return ret
   128  }
   129  
   130  func Sum(sha hash.Hash) []byte {
   131  	//in := make([]byte, 32)
   132  	return sha.Sum(nil)
   133  }
   134  
   135  func (dag *Dagger) Eval(N *big.Int) *big.Int {
   136  	pow := ethutil.BigPow(2, 26)
   137  	dag.xn = pow.Div(N, pow)
   138  
   139  	sha := sha3.NewKeccak256()
   140  	sha.Reset()
   141  	ret := new(big.Int)
   142  
   143  	for k := 0; k < 4; k++ {
   144  		d := sha3.NewKeccak256()
   145  		b := new(big.Int)
   146  
   147  		d.Reset()
   148  		d.Write(dag.hash.Bytes())
   149  		d.Write(dag.xn.Bytes())
   150  		d.Write(N.Bytes())
   151  		d.Write(big.NewInt(int64(k)).Bytes())
   152  
   153  		b.SetBytes(Sum(d))
   154  		pk := (b.Uint64() & 0x1ffffff)
   155  
   156  		sha.Write(dag.Node(9, pk).Bytes())
   157  	}
   158  
   159  	return ret.SetBytes(Sum(sha))
   160  }