Allow creation of Account without knowing the seed

account.go

@@ -18,11 +18,10 @@ var ErrAccountNotFound = fmt.Errorf("account has not yet been opened")
 // manipulated. This probably means someone is trying to steal funds.
 var ErrAccountManipulated = fmt.Errorf("the received account info has been manipulated")
 
-// Account holds the keys and address of a Nano account.
+// Account holds the public key and address of a Nano account.
 type Account struct {
-	PrivateKey *big.Int
-	PublicKey  *big.Int
-	Address    string
+	PublicKey *big.Int
+	Address   string
 }
 
 type blockInfo struct {
@@ -30,20 +29,19 @@ type blockInfo struct {
 	Contents Block  `json:"contents"`
 }
 
-// NewAccount creates a new Account and populates all its fields.
-func NewAccount(seed *big.Int, index uint32) (a Account, err error) {
-	a.PrivateKey = getPrivateKey(seed, index)
-	a.PublicKey = derivePublicKey(a.PrivateKey)
+// NewAccount creates a new Account and populates both its fields.
+func NewAccount(privateKey *big.Int) (a Account, err error) {
+	a.PublicKey = derivePublicKey(privateKey)
 	a.Address, err = getAddress(a.PublicKey)
 	return
 }
 
-func getPrivateKey(seed *big.Int, index uint32) *big.Int {
-	seedBytes := bigIntToBytes(seed, 32)
-	indexBytes := bigIntToBytes(big.NewInt(int64(index)), 4)
-	in := append(seedBytes, indexBytes...)
-	privateKeyBytes := blake2b.Sum256(in)
-	return big.NewInt(0).SetBytes(privateKeyBytes[:])
+// NewAccountFromAddress creates a new Account and populates both its
+// fields.
+func NewAccountFromAddress(address string) (a Account, err error) {
+	a.Address = address
+	a.PublicKey, err = getPublicKeyFromAddress(address)
+	return
 }
 
 func derivePublicKey(privateKey *big.Int) *big.Int {

cmd/atto/main.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"math/big"
 	"os"
+
+	"github.com/codesoap/atto"
 )
 
 var usage = `Usage:
@@ -102,7 +104,12 @@ func printNewSeed() error {
 }
 
 func printAddress() error {
-	account, err := ownAccount()
+	seed, err := getSeed()
+	if err != nil {
+		return err
+	}
+	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	account, err := atto.NewAccount(privateKey)
 	if err == nil {
 		fmt.Println(account.Address)
 	}
@@ -110,7 +117,12 @@ func printAddress() error {
 }
 
 func printBalance() error {
-	account, err := ownAccount()
+	seed, err := getSeed()
+	if err != nil {
+		return err
+	}
+	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	account, err := atto.NewAccount(privateKey)
 	if err != nil {
 		return err
 	}
@@ -133,7 +145,7 @@ func printBalance() error {
 		if err != nil {
 			return err
 		}
-		if err = block.Sign(account.PublicKey, account.PrivateKey); err != nil {
+		if err = block.Sign(account.PublicKey, privateKey); err != nil {
 			return err
 		}
 		if err = block.FetchWork(sendWorkThreshold, account.PublicKey, node); err != nil {
@@ -154,7 +166,12 @@ func printBalance() error {
 
 func changeRepresentative() error {
 	representative := flag.Arg(1)
-	account, err := ownAccount()
+	seed, err := getSeed()
+	if err != nil {
+		return err
+	}
+	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	account, err := atto.NewAccount(privateKey)
 	if err != nil {
 		return err
 	}
@@ -168,7 +185,7 @@ func changeRepresentative() error {
 	if err != nil {
 		return err
 	}
-	if err = block.Sign(account.PublicKey, account.PrivateKey); err != nil {
+	if err = block.Sign(account.PublicKey, privateKey); err != nil {
 		return err
 	}
 	if err = block.FetchWork(sendWorkThreshold, account.PublicKey, node); err != nil {
@@ -184,7 +201,12 @@ func changeRepresentative() error {
 func sendFunds() error {
 	amount := flag.Arg(1)
 	recipient := flag.Arg(2)
-	account, err := ownAccount()
+	seed, err := getSeed()
+	if err != nil {
+		return err
+	}
+	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	account, err := atto.NewAccount(privateKey)
 	if err != nil {
 		return err
 	}
@@ -201,7 +223,7 @@ func sendFunds() error {
 	if err != nil {
 		return err
 	}
-	if err = block.Sign(account.PublicKey, account.PrivateKey); err != nil {
+	if err = block.Sign(account.PublicKey, privateKey); err != nil {
 		return err
 	}
 	if err = block.FetchWork(sendWorkThreshold, account.PublicKey, node); err != nil {

cmd/atto/util.go

@@ -7,20 +7,8 @@ import (
 	"os"
 	"runtime"
 	"strings"
-
-	"github.com/codesoap/atto"
 )
 
-// ownAccount initializes the own account using the seed provided via
-// standard input and accountIndexFlag.
-func ownAccount() (atto.Account, error) {
-	seed, err := getSeed()
-	if err != nil {
-		return atto.Account{}, err
-	}
-	return atto.NewAccount(seed, uint32(accountIndexFlag))
-}
-
 // getSeed takes the first line of the standard input and interprets it
 // as a hexadecimal representation of a 32byte seed.
 func getSeed() (*big.Int, error) {

util.go

@@ -6,8 +6,19 @@ import (
 	"math/big"
 	"net/http"
 	"strings"
+
+	"golang.org/x/crypto/blake2b"
 )
 
+// NewPrivateKey creates a private key from the given seed and index.
+func NewPrivateKey(seed *big.Int, index uint32) *big.Int {
+	seedBytes := bigIntToBytes(seed, 32)
+	indexBytes := bigIntToBytes(big.NewInt(int64(index)), 4)
+	in := append(seedBytes, indexBytes...)
+	privateKeyBytes := blake2b.Sum256(in)
+	return big.NewInt(0).SetBytes(privateKeyBytes[:])
+}
+
 func base32Encode(in *big.Int) string {
 	alphabet := []byte("13456789abcdefghijkmnopqrstuwxyz")
 	bigZero := big.NewInt(0)