Move seed generation into library

cmd/atto/main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"crypto/rand"
 	"flag"
 	"fmt"
 	"math/big"
@@ -95,12 +94,11 @@ func main() {
 }
 
 func printNewSeed() error {
-	b := make([]byte, 32)
-	if _, err := rand.Read(b); err != nil {
-		return err
+	seed, err := atto.GenerateSeed()
+	if err == nil {
+		fmt.Println(seed)
 	}
-	fmt.Printf("%X\n", b)
-	return nil
+	return err
 }
 
 func printAddress() error {
@@ -108,7 +106,10 @@ func printAddress() error {
 	if err != nil {
 		return err
 	}
-	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	privateKey, err := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	if err != nil {
+		return err
+	}
 	account, err := atto.NewAccount(privateKey)
 	if err == nil {
 		fmt.Println(account.Address)
@@ -121,7 +122,10 @@ func printBalance() error {
 	if err != nil {
 		return err
 	}
-	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	privateKey, err := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	if err != nil {
+		return err
+	}
 	account, err := atto.NewAccount(privateKey)
 	if err != nil {
 		return err
@@ -170,7 +174,10 @@ func changeRepresentative() error {
 	if err != nil {
 		return err
 	}
-	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	privateKey, err := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	if err != nil {
+		return err
+	}
 	account, err := atto.NewAccount(privateKey)
 	if err != nil {
 		return err
@@ -205,7 +212,10 @@ func sendFunds() error {
 	if err != nil {
 		return err
 	}
-	privateKey := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	privateKey, err := atto.NewPrivateKey(seed, uint32(accountIndexFlag))
+	if err != nil {
+		return err
+	}
 	account, err := atto.NewAccount(privateKey)
 	if err != nil {
 		return err

cmd/atto/util.go

@@ -9,19 +9,14 @@ import (
 	"strings"
 )
 
-// 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) {
+// getSeed returns the first line of the standard input.
+func getSeed() (string, error) {
 	in := bufio.NewReader(os.Stdin)
 	firstLine, err := in.ReadString('\n')
 	if err != nil {
-		return nil, err
+		return "", err
 	}
-	seed, ok := big.NewInt(0).SetString(strings.TrimSpace(firstLine), 16)
-	if !ok {
-		return nil, fmt.Errorf("could not parse seed")
-	}
-	return seed, nil
+	return strings.TrimSpace(firstLine), nil
 }
 
 func rawToNanoString(raw *big.Int) string {

util.go

@@ -1,6 +1,7 @@
 package atto
 
 import (
+	"crypto/rand"
 	"fmt"
 	"io/ioutil"
 	"math/big"
@@ -10,13 +11,24 @@ import (
 	"golang.org/x/crypto/blake2b"
 )
 
+// GenerateSeed generates a new random seed.
+func GenerateSeed() (string, error) {
+	b := make([]byte, 32)
+	_, err := rand.Read(b)
+	return fmt.Sprintf("%X\n", b), err
+}
+
 // NewPrivateKey creates a private key from the given seed and index.
-func NewPrivateKey(seed *big.Int, index uint32) *big.Int {
-	seedBytes := bigIntToBytes(seed, 32)
+func NewPrivateKey(seed string, index uint32) (*big.Int, error) {
+	seedInt, ok := big.NewInt(0).SetString(seed, 16)
+	if !ok {
+		return nil, fmt.Errorf("could not parse seed")
+	}
+	seedBytes := bigIntToBytes(seedInt, 32)
 	indexBytes := bigIntToBytes(big.NewInt(int64(index)), 4)
 	in := append(seedBytes, indexBytes...)
 	privateKeyBytes := blake2b.Sum256(in)
-	return big.NewInt(0).SetBytes(privateKeyBytes[:])
+	return big.NewInt(0).SetBytes(privateKeyBytes[:]), nil
 }
 
 func base32Encode(in *big.Int) string {