M core/blockchain.go → core/blockchain.go

@@ -143,7 +143,20 @@ fmt.Println("block.Height error")
 		return false
 	}
 
-	// verify block transactions
+	// verify block transactions (not if the block is the genesis block)
+	if !bytes.Equal(block.Txs[0].TxId[:], GenesisHashTxInput[:]) {
+		for _, tx := range block.Txs {
+			txVerified := CheckTx(&tx)
+			if !txVerified {
+				fmt.Println("tx could not be verified")
+				return false
+			}
+		}
+	}
+
+	// TODO in --> out0
+	//          -> out1
+	//          -> ...
 
 	return true
 }

M core/tx.go → core/tx.go

@@ -1,6 +1,12 @@
 package core
 
-import "crypto/ecdsa"
+import (
+	"crypto/ecdsa"
+	"encoding/json"
+	"fmt"
+)
+
+var GenesisHashTxInput = HashBytes([]byte("genesis"))
 
 type Input struct {
 	TxId  Hash
@@ -14,6 +20,7 @@ }
 
 // Tx holds the data structure of a transaction
 type Tx struct {
+	TxId       Hash
 	From       *ecdsa.PublicKey
 	To         *ecdsa.PublicKey
 	InputCount uint64
@@ -22,6 +29,17 @@ Outputs    []Output
 	Signature  []byte
 }
 
+func (tx *Tx) Bytes() []byte {
+	// TODO add parser, to use minimum amount of bytes
+	b, _ := json.Marshal(tx)
+	return b
+}
+
+func (tx *Tx) CalculateTxId() {
+	h := HashBytes(tx.Bytes())
+	tx.TxId = h
+}
+
 func NewTx(from, to *ecdsa.PublicKey, in []Input, out []Output) *Tx {
 	tx := &Tx{
 		From:       from,
@@ -29,7 +47,9 @@ To:         to,
 		InputCount: uint64(len(in)),
 		Inputs:     in,
 		Outputs:    out,
+		Signature:  []byte{},
 	}
+	tx.CalculateTxId()
 	return tx
 }
 
@@ -46,7 +66,8 @@ totalOut := 0
 	for _, out := range tx.Outputs {
 		totalOut = totalOut + int(out.Value)
 	}
-	if totalIn < totalOut {
+	if totalIn != totalOut {
+		fmt.Println("totalIn != totalOut")
 		return false
 	}
 

M node/node.go → node/node.go

@@ -85,11 +85,45 @@ }
 	return block, nil
 }
 
-func (node *Node) CreateGenesis() (*core.Block, error) {
+func (node *Node) CreateGenesis(pubK *ecdsa.PublicKey, amount uint64) (*core.Block, error) {
+	// pubK is the wallet where the first coins will be created
+	// amount is the amount of coins that will be created
+
+	in := core.Input{
+		TxId:  core.GenesisHashTxInput,
+		Vout:  0,
+		Value: amount,
+	}
+	var ins []core.Input
+	ins = append(ins, in)
+
+	out := core.Output{
+		Value: amount,
+	}
+	var outs []core.Output
+	outs = append(outs, out)
+
+	tx := core.Tx{
+		From:       &ecdsa.PublicKey{},
+		To:         pubK,
+		InputCount: uint64(0),
+		Inputs:     []core.Input{},
+		Outputs:    outs,
+		Signature:  []byte{},
+	}
+
+	// calculate TxId
+	// tx.CalculateTxId()
+	tx.TxId = core.GenesisHashTxInput
+	// sign transaction
+
+	var txs []core.Tx
+	txs = append(txs, tx)
+
 	block := &core.Block{
 		Height:    node.Bc.LastBlock.Height + 1,
 		PrevHash:  node.Bc.LastBlock.Hash,
-		Txs:       []core.Tx{},
+		Txs:       txs,
 		Miner:     node.Addr,
 		MinerPubK: &node.PrivK.PublicKey,
 		Timestamp: time.Now(),

M node/node_test.go → node/node_test.go

@@ -122,22 +122,81 @@ node, err := NewNode(privK, bc, true)
 	assert.Nil(t, err)
 
 	// create the genesis block
-	genesisBlock, err := node.CreateGenesis()
+	genesisBlock, err := node.CreateGenesis(&privK.PublicKey, uint64(100))
 	assert.Nil(t, err)
 	assert.NotEqual(t, genesisBlock.Signature, core.Signature{})
 	assert.NotEqual(t, genesisBlock.Hash, core.Hash{})
+	assert.True(t, node.Bc.VerifyBlock(genesisBlock))
 
-	assert.True(t, node.Bc.VerifyBlock(genesisBlock))
 	// add the genesis block into the blockchain
 	err = node.Bc.AddBlock(genesisBlock)
 	assert.Nil(t, err)
 	assert.NotEqual(t, genesisBlock.Hash, core.Hash{})
 	assert.Equal(t, genesisBlock.Hash, node.Bc.LastBlock.Hash)
 
-	// TODO add another block
-	block, err := node.NewBlock([]core.Tx{})
+	// add another tx sending coins to the pubK0
+	privK0, err := core.NewKey()
+	assert.Nil(t, err)
+	pubK0 := privK0.PublicKey
+
+	var ins []core.Input
+	in := core.Input{
+		TxId:  genesisBlock.Txs[0].TxId,
+		Vout:  0,
+		Value: 100,
+	}
+	ins = append(ins, in)
+	var outs []core.Output
+	out0 := core.Output{
+		Value: 10,
+	}
+	out1 := core.Output{
+		Value: 90,
+	}
+	outs = append(outs, out0)
+	outs = append(outs, out1)
+	tx := core.NewTx(&privK.PublicKey, &pubK0, ins, outs)
+
+	// verify tx
+	txVerified := core.CheckTx(tx)
+	assert.True(t, txVerified)
+
+	// then create a new block with the tx and add it to the blockchain
+	var txs []core.Tx
+	txs = append(txs, *tx)
+	block, err := node.NewBlock(txs)
+	assert.Nil(t, err)
+	err = node.Bc.AddBlock(block)
+	assert.Nil(t, err)
+
+	// add another tx sending coins to the pubK1
+	privK1, err := core.NewKey()
 	assert.Nil(t, err)
-	block.Print()
+	pubK1 := privK1.PublicKey
+
+	ins = []core.Input{}
+	in = core.Input{
+		TxId:  block.Txs[0].TxId,
+		Vout:  0,
+		Value: 10,
+	}
+	ins = append(ins, in)
+	outs = []core.Output{}
+	out0 = core.Output{
+		Value: 10,
+	}
+	outs = append(outs, out0)
+	tx = core.NewTx(&pubK0, &pubK1, ins, outs)
+
+	// verify tx
+	txVerified = core.CheckTx(tx)
+	assert.True(t, txVerified)
+
+	// then create a new block with the tx and add it to the blockchain
+	txs = []core.Tx{}
+	txs = append(txs, *tx)
+	block, err = node.NewBlock(txs)
+	assert.Nil(t, err)
 	err = node.Bc.AddBlock(block)
 	assert.Nil(t, err)
 }