add util to get onion address from private key (#39)

* add util to get onion address from private key

* PR comments: added test, using go-ricochet errors, function argument a privateKey

* remove unnecesary cast and variable

utils/crypto.go

@@ -9,6 +9,7 @@ import (
 	"io/ioutil"
 	"math"
 	"math/big"
+	"github.com/yawning/bulb/utils/pkcs1"
 )
 
 const (
@@ -69,3 +70,14 @@ func PrivateKeyToString(privateKey *rsa.PrivateKey) string {
 
 	return string(pem.EncodeToMemory(&privateKeyBlock))
 }
+
+// return an onion address from a private key
+func GetOnionAddress(privateKey *rsa.PrivateKey) (string, error) {
+	addr, err := pkcs1.OnionAddr(&privateKey.PublicKey)
+	if err != nil {
+		return "", err
+	} else if addr == "" {
+		return "", OnionAddressGenerationError
+	}
+	return addr, nil
+}

utils/crypto_test.go

@@ -5,6 +5,10 @@ import (
 	"testing"
 )
 
+const (
+	privateKeyFile = "./../testing/private_key"
+)
+
 func TestGeneratePrivateKey(t *testing.T) {
 	_, err := GeneratePrivateKey()
 	if err != nil {
@@ -13,7 +17,7 @@ func TestGeneratePrivateKey(t *testing.T) {
 }
 
 func TestLoadPrivateKey(t *testing.T) {
-	_, err := LoadPrivateKeyFromFile("../testing/private_key")
+	_, err := LoadPrivateKeyFromFile(privateKeyFile)
 	if err != nil {
 		t.Errorf("Error while loading private key from file: %v", err)
 	}
@@ -25,3 +29,14 @@ func TestGetRandNumber(t *testing.T) {
 		t.Errorf("Error random number outside of expected bounds %v", num)
 	}
 }
+
+func TestGetOnionAddress(t *testing.T) {
+	privateKey, _ := LoadPrivateKeyFromFile(privateKeyFile)
+	address, err := GetOnionAddress(privateKey)
+	if err != nil {
+		t.Errorf("Error generating onion address from private key: %v", err)
+	}
+	if address != "kwke2hntvyfqm7dr" {
+		t.Errorf("Error: onion address for private key not expected value")
+	}
+}

utils/error.go

@@ -40,6 +40,7 @@ const (
 
 	// Library Use Errors
 	PrivateKeyNotSetError = Error("ClientFailedToAuthenticateError")
+	OnionAddressGenerationError = Error("OnionAddressGenerationError")
 
 	// Connection Errors
 	ConnectionClosedError = Error("ConnectionClosedError")