从命令行开始解析以太坊新建账户过程（geth account new命令）
如上图是生成一个账户的过程，最后的账户表现为一个地址那么，这个过程的代码是怎么实现的呢，接下来我们从main函数命令行开始解析这个过程的代码。
在cmd/geth/main.go中的init函数中，有一个accountCommand的命令行参数
func init() {
// Initialize the CLI app and start Geth
app.Action = geth
app.HideVersion = true // we have a command to print the version
app.Copyright = "Copyright 2013-2018 The go-ethereum Authors"
app.Commands = []cli.Command{
// See chaincmd.go:
initCommand,
importCommand,
exportCommand,
importPreimagesCommand,
exportPreimagesCommand,
copydbCommand,
removedbCommand,
dumpCommand,
// See monitorcmd.go:
monitorCommand,
// See accountcmd.go:
accountCommand,
walletCommand,
// See consolecmd.go:
consoleCommand,
attachCommand,
javascriptCommand,
// See misccmd.go:
makecacheCommand,
makedagCommand,
versionCommand,
bugCommand,
licenseCommand,
// See config.go
dumpConfigCommand,
}
sort.Sort(cli.CommandsByName(app.Commands))
app.Flags = append(app.Flags, nodeFlags...)
app.Flags = append(app.Flags, rpcFlags...)
app.Flags = append(app.Flags, consoleFlags...)
app.Flags = append(app.Flags, debug.Flags...)
app.Flags = append(app.Flags, whisperFlags...)
app.Before = func(ctx *cli.Context) error {
runtime.GOMAXPROCS(runtime.NumCPU())
if err := debug.Setup(ctx); err != nil {
return err
}
// Start system runtime metrics collection
go metrics.CollectProcessMetrics(3 * time.Second)
utils.SetupNetwork(ctx)
return nil
}
app.After = func(ctx *cli.Context) error {
debug.Exit()
console.Stdin.Close() // Resets terminal mode.
return nil
}
}
账户相关的命令在cmd/geth/accountcmd.go里，新建账户命令为new，其会调accountCreate方法，我们继续看：
accountCommand = cli.Command{
Name: "account",
Usage: "Manage accounts",
Category: "ACCOUNT COMMANDS",
子命令：
{
Name: "new",
Usage: "Create a new account",
Action: utils.MigrateFlags(accountCreate),
Flags: []cli.Flag{
utils.DataDirFlag,
utils.KeyStoreDirFlag,
utils.PasswordFileFlag,
utils.LightKDFFlag,
},
Description: `
geth account new
Creates a new account and prints the address.
The account is saved in encrypted format, you are prompted for a passphrase.
You must remember this passphrase to unlock your account in the future.
For non-interactive use the passphrase can be specified with the --password flag:
Note, this is meant to be used for testing only, it is a bad idea to save your
password to file or expose in any other way.
`,
}
账户相关的命令在cmd/geth/accountcmd.go里，新建账户命令为new，其会调accountCreate方法，accountCreate在CLI标志定义的密钥库中创建一个新帐户
func accountCreate(ctx *cli.Context) error {
cfg := gethConfig{Node: defaultNodeConfig()}
// Load config file.
if file := ctx.GlobalString(configFileFlag.Name); file != "" {
if err := loadConfig(file, &cfg); err != nil {
utils.Fatalf("%v", err)
}
}
utils.SetNodeConfig(ctx, &cfg.Node)
scryptN, scryptP, keydir, err := cfg.Node.AccountConfig()
if err != nil {
utils.Fatalf("Failed to read configuration: %v", err)
}
password := getPassPhrase("Your new account is locked with a password. Please give a password. Do not forget this password.", true, 0, utils.MakePasswordList(ctx))
address, err := keystore.StoreKey(keydir, password, scryptN, scryptP)
if err != nil {
utils.Fatalf("Failed to create account: %v", err)
}
fmt.Printf("Address: {%x}\n", address)
return nil
}
获取配置并解析用户的密码, StoreKey生成一个密钥，用’auth’加密并存储在给定的目录中
func StoreKey(dir, auth string, scryptN, scryptP int) (common.Address, error) {
_, a, err := storeNewKey(&keyStorePassphrase{dir, scryptN, scryptP}, crand.Reader, auth)
return a.Address, err
}
storeNewKey()来创建一个新的账户，具体表现为生成一对公私钥，再由私钥算出地址并构建一个自定义的Key
func storeNewKey(ks keyStore, rand io.Reader, auth string) (*Key, accounts.Account, error) {
key, err := newKey(rand)
if err != nil {
return nil, accounts.Account{}, err
}
a := accounts.Account{Address: key.Address, URL: accounts.URL{Scheme: KeyStoreScheme, Path: ks.JoinPath(keyFileName(key.Address))}}
if err := ks.StoreKey(a.URL.Path, key, auth); err != nil {
zeroKey(key.PrivateKey)
return nil, a, err
}
return key, a, err
}
Key的生成函数，通过椭圆曲线加密生成的私钥，生成Key
func newKey(rand io.Reader) (*Key, error) {
privateKeyECDSA, err := ecdsa.GenerateKey(crypto.S256(), rand)
if err != nil {
return nil, err
}
return newKeyFromECDSA(privateKeyECDSA), nil
}
生成公钥和私钥对,ecdsa.GenerateKey(crypto.S256(), rand) 以太坊采用了椭圆曲线数字签名算法（ECDSA）生成一对公私钥，并选择的是secp256k1曲线
func GenerateKey(c elliptic.Curve, rand io.Reader) (*PrivateKey, error) {
k, err := randFieldElement(c, rand)
if err != nil {
return nil, err
}
priv := new(PrivateKey)
priv.PublicKey.Curve = c
priv.D = k
priv.PublicKey.X, priv.PublicKey.Y = c.ScalarBaseMult(k.Bytes())
return priv, nil
}
以太坊使用私钥通过 ECDSA算法推导出公钥，继而经过 Keccak-256 单向散列函数推导出地址
func newKeyFromECDSA(privateKeyECDSA *ecdsa.PrivateKey) *Key {
id := uuid.NewRandom()
key := &Key{
Id: id,
Address: crypto.PubkeyToAddress(privateKeyECDSA.PublicKey),
PrivateKey: privateKeyECDSA,
}
return key
}
func PubkeyToAddress(p ecdsa.PublicKey) common.Address {
pubBytes := FromECDSAPub(&p)
return common.BytesToAddress(Keccak256(pubBytes[1:])[12:])
}
地址代表以太坊帐户的20字节地址
const (
HashLength = 32
AddressLength = 20
)
type Address [AddressLength]byte
func BytesToAddress(b []byte) Address {
var a Address
a.SetBytes(b)
return a
}
func BigToAddress(b *big.Int) Address { return BytesToAddress(b.Bytes()) }
func HexToAddress(s string) Address { return BytesToAddress(FromHex(s)) }
总结，整个过程如下：
- 创建随机私钥 (64 位 16 进制字符 / 32 字节)
- 从私钥推导出公钥 (128 位 16 进制字符 / 64 字节)
- 从公钥推导出地址 (40 位 16 进制字符 / 20 字节)