Implement address generation and wallets

address.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"log"
+
+	"golang.org/x/crypto/ripemd160"
+)
+
+const version = byte(0x00)
+
+// Wallet ...
+type Wallet struct {
+	PrivateKey []byte
+	PublicKey  []byte
+}
+
+// GetAddress returns wallet address
+func (w Wallet) GetAddress() []byte {
+	publicSHA256 := sha256.Sum256(w.PublicKey)
+
+	RIPEMD160Hasher := ripemd160.New()
+	_, err := RIPEMD160Hasher.Write(publicSHA256[:])
+	if err != nil {
+		log.Panic(err)
+	}
+	publicRIPEMD160 := RIPEMD160Hasher.Sum(nil)
+
+	versionedPayload := append([]byte{version}, publicRIPEMD160...)
+	checksum := checksum(versionedPayload)
+
+	fullPayload := append(versionedPayload, checksum...)
+	address := Base58Encode(fullPayload)
+
+	return address
+}
+
+// NewWallet ...
+func NewWallet() *Wallet {
+	private, public := newKeyPair()
+	wallet := Wallet{private, public}
+
+	return &wallet
+}
+
+func newKeyPair() ([]byte, []byte) {
+	curve := elliptic.P256()
+	private, x, y, err := elliptic.GenerateKey(curve, rand.Reader)
+	if err != nil {
+		log.Panic(err)
+	}
+
+	public := append(x.Bytes(), y.Bytes()...)
+
+	return private, public
+}
+
+// Checksum ...
+func checksum(payload []byte) []byte {
+	firstSHA := sha256.Sum256(payload)
+	secondSHA := sha256.Sum256(firstSHA[:])
+
+	return secondSHA[:4]
+}

base58.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"math/big"
+)
+
+var alphabet = []byte("123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz")
+
+// Base58Encode encodes a byte array to Base58
+func Base58Encode(input []byte) []byte {
+	var result []byte
+
+	x := big.NewInt(0)
+	x.SetBytes(input)
+
+	base := big.NewInt(int64(len(alphabet)))
+	zero := big.NewInt(0)
+	mod := &big.Int{}
+
+	for x.Cmp(zero) != 0 {
+		x.DivMod(x, base, mod)
+		result = append(result, alphabet[mod.Int64()])
+	}
+
+	ReverseBytes(result)
+	for c := range input {
+		if c == 0x00 {
+			result = append([]byte{alphabet[0]}, result...)
+		} else {
+			break
+		}
+	}
+
+	return result
+}

cli.go

@@ -17,6 +17,11 @@ func (cli *CLI) createBlockchain(address string) {
 	fmt.Println("Done!")
 }
 
+func (cli *CLI) createWallet() {
+	wallet := NewWallet()
+	fmt.Printf("Your address: %s\n", wallet.GetAddress())
+}
+
 func (cli *CLI) getBalance(address string) {
 	bc := NewBlockchain(address)
 	defer bc.db.Close()
@@ -83,6 +88,7 @@ func (cli *CLI) Run() {
 
 	getBalanceCmd := flag.NewFlagSet("getbalance", flag.ExitOnError)
 	createBlockchainCmd := flag.NewFlagSet("createblockchain", flag.ExitOnError)
+	createWalletCmd := flag.NewFlagSet("createwallet", flag.ExitOnError)
 	sendCmd := flag.NewFlagSet("send", flag.ExitOnError)
 	printChainCmd := flag.NewFlagSet("printchain", flag.ExitOnError)
 
@@ -103,6 +109,11 @@ func (cli *CLI) Run() {
 		if err != nil {
 			log.Panic(err)
 		}
+	case "createwallet":
+		err := createWalletCmd.Parse(os.Args[2:])
+		if err != nil {
+			log.Panic(err)
+		}
 	case "printchain":
 		err := printChainCmd.Parse(os.Args[2:])
 		if err != nil {
@@ -134,6 +145,10 @@ func (cli *CLI) Run() {
 		cli.createBlockchain(*createBlockchainAddress)
 	}
 
+	if createWalletCmd.Parsed() {
+		cli.createWallet()
+	}
+
 	if printChainCmd.Parsed() {
 		cli.printChain()
 	}

utils.go

@@ -16,3 +16,10 @@ func IntToHex(num int64) []byte {
 
 	return buff.Bytes()
 }
+
+// ReverseBytes reverses a byte array
+func ReverseBytes(data []byte) {
+	for i, j := 0, len(data)-1; i < j; i, j = i+1, j-1 {
+		data[i], data[j] = data[j], data[i]
+	}
+}