Unexport the cryptoKey type.

The crypto key type unsed in the manager is not needed outside of the
package.  Also, rather than having the newCryptoKey func return the
specific cryptoKey type, make it return the EncryptorDecryptor interface.
This will allow it to be overridden with another type that implements the
interface from the tests.

waddrmgr/manager.go

@@ -142,31 +142,31 @@ type EncryptorDecryptor interface {
 	Zero()
 }
 
-// CryptoKey extends snacl.CryptoKey to implement EncryptorDecryptor.
-type CryptoKey struct {
+// cryptoKey extends snacl.CryptoKey to implement EncryptorDecryptor.
+type cryptoKey struct {
 	snacl.CryptoKey
 }
 
 // Bytes returns a copy of this crypto key's byte slice.
-func (ck *CryptoKey) Bytes() []byte {
+func (ck *cryptoKey) Bytes() []byte {
 	return ck.CryptoKey[:]
 }
 
 // CopyBytes copies the bytes from the given slice into this CryptoKey.
-func (ck *CryptoKey) CopyBytes(from []byte) {
+func (ck *cryptoKey) CopyBytes(from []byte) {
 	copy(ck.CryptoKey[:], from)
 }
 
 // defaultNewCryptoKey returns a new CryptoKey.  See newCryptoKey.
-func defaultNewCryptoKey() (*CryptoKey, error) {
+func defaultNewCryptoKey() (EncryptorDecryptor, error) {
 	key, err := snacl.GenerateCryptoKey()
 	if err != nil {
 		return nil, err
 	}
-	return &CryptoKey{*key}, nil
+	return &cryptoKey{*key}, nil
 }
 
-// newCryptoKey is used as a way to replace the new CryptoKey generation
+// newCryptoKey is used as a way to replace the new crypto key generation
 // function used so tests can provide a version that fails for testing error
 // paths.
 var newCryptoKey = defaultNewCryptoKey
@@ -1445,7 +1445,7 @@ func (m *Manager) AllActiveAddresses() ([]btcutil.Address, error) {
 
 // newManager returns a new locked address manager with the given parameters.
 func newManager(db *managerDB, net *btcnet.Params, masterKeyPub *snacl.SecretKey,
-	masterKeyPriv *snacl.SecretKey, cryptoKeyPub *CryptoKey,
+	masterKeyPriv *snacl.SecretKey, cryptoKeyPub EncryptorDecryptor,
 	cryptoKeyPrivEncrypted, cryptoKeyScriptEncrypted []byte,
 	syncInfo *syncState) *Manager {
 
@@ -1460,9 +1460,9 @@ func newManager(db *managerDB, net *btcnet.Params, masterKeyPub *snacl.SecretKey
 		masterKeyPriv:            masterKeyPriv,
 		cryptoKeyPub:             cryptoKeyPub,
 		cryptoKeyPrivEncrypted:   cryptoKeyPrivEncrypted,
-		cryptoKeyPriv:            &CryptoKey{},
+		cryptoKeyPriv:            &cryptoKey{},
 		cryptoKeyScriptEncrypted: cryptoKeyScriptEncrypted,
-		cryptoKeyScript:          &CryptoKey{},
+		cryptoKeyScript:          &cryptoKey{},
 	}
 }
 
@@ -1614,7 +1614,7 @@ func loadManager(db *managerDB, pubPassphrase []byte, net *btcnet.Params) (*Mana
 	}
 
 	// Use the master public key to decrypt the crypto public key.
-	cryptoKeyPub := &CryptoKey{snacl.CryptoKey{}}
+	cryptoKeyPub := &cryptoKey{snacl.CryptoKey{}}
 	cryptoKeyPubCT, err := masterKeyPub.Decrypt(cryptoKeyPubEnc)
 	if err != nil {
 		str := "failed to decrypt crypto public key"