diff --git a/proxy/shadowsocks/client.go b/proxy/shadowsocks/client.go
index 231834e99..d86127c21 100644
--- a/proxy/shadowsocks/client.go
+++ b/proxy/shadowsocks/client.go
@@ -97,7 +97,7 @@ func (v *Client) Process(ctx context.Context, outboundRay ray.OutboundRay, diale
 	if err != nil {
 		return newError("failed to get a valid user account").AtWarning().Base(err)
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 	request.User = user
 
 	if account.OneTimeAuth == Account_Auto || account.OneTimeAuth == Account_Enabled {
diff --git a/proxy/shadowsocks/config.go b/proxy/shadowsocks/config.go
index 1479cc863..54de878f0 100644
--- a/proxy/shadowsocks/config.go
+++ b/proxy/shadowsocks/config.go
@@ -17,15 +17,17 @@ import (
 	"v2ray.com/core/common/protocol"
 )
 
-type ShadowsocksAccount struct {
+// MemoryAccount is an account type converted from Account.
+type MemoryAccount struct {
 	Cipher      Cipher
 	Key         []byte
 	OneTimeAuth Account_OneTimeAuth
 }
 
-func (v *ShadowsocksAccount) Equals(another protocol.Account) bool {
-	if account, ok := another.(*ShadowsocksAccount); ok {
-		return bytes.Equal(v.Key, account.Key)
+// Equals implements protocol.Account.Equals().
+func (a *MemoryAccount) Equals(another protocol.Account) bool {
+	if account, ok := another.(*MemoryAccount); ok {
+		return bytes.Equal(a.Key, account.Key)
 	}
 	return false
 }
@@ -44,7 +46,7 @@ func createChacha20Poly1305(key []byte) cipher.AEAD {
 	return chacha20
 }
 
-func (a *Account) GetCipher() (Cipher, error) {
+func (a *Account) getCipher() (Cipher, error) {
 	switch a.CipherType {
 	case CipherType_AES_128_CFB:
 		return &AesCfb{KeyBytes: 16}, nil
@@ -79,18 +81,20 @@ func (a *Account) GetCipher() (Cipher, error) {
 	}
 }
 
+// AsAccount implements protocol.AsAccount.
 func (a *Account) AsAccount() (protocol.Account, error) {
-	cipher, err := a.GetCipher()
+	cipher, err := a.getCipher()
 	if err != nil {
 		return nil, newError("failed to get cipher").Base(err)
 	}
-	return &ShadowsocksAccount{
+	return &MemoryAccount{
 		Cipher:      cipher,
-		Key:         PasswordToCipherKey([]byte(a.Password), cipher.KeySize()),
+		Key:         passwordToCipherKey([]byte(a.Password), cipher.KeySize()),
 		OneTimeAuth: a.Ota,
 	}, nil
 }
 
+// Cipher is an interface for all Shadowsocks ciphers.
 type Cipher interface {
 	KeySize() int
 	IVSize() int
@@ -101,6 +105,7 @@ type Cipher interface {
 	DecodePacket(key []byte, b *buf.Buffer) error
 }
 
+// AesCfb represents all AES-CFB ciphers.
 type AesCfb struct {
 	KeyBytes int
 }
@@ -279,7 +284,7 @@ func (NoneCipher) DecodePacket(key []byte, b *buf.Buffer) error {
 	return nil
 }
 
-func PasswordToCipherKey(password []byte, keySize int) []byte {
+func passwordToCipherKey(password []byte, keySize int) []byte {
 	key := make([]byte, 0, keySize)
 
 	md5Sum := md5.Sum(password)
@@ -287,8 +292,8 @@ func PasswordToCipherKey(password []byte, keySize int) []byte {
 
 	for len(key) < keySize {
 		md5Hash := md5.New()
-		md5Hash.Write(md5Sum[:])
-		md5Hash.Write(password)
+		common.Must2(md5Hash.Write(md5Sum[:]))
+		common.Must2(md5Hash.Write(password))
 		md5Hash.Sum(md5Sum[:0])
 
 		key = append(key, md5Sum[:]...)
diff --git a/proxy/shadowsocks/ota.go b/proxy/shadowsocks/ota.go
index 91549b829..3d9396822 100644
--- a/proxy/shadowsocks/ota.go
+++ b/proxy/shadowsocks/ota.go
@@ -6,6 +6,7 @@ import (
 	"crypto/sha1"
 	"io"
 
+	"v2ray.com/core/common"
 	"v2ray.com/core/common/buf"
 	"v2ray.com/core/common/serial"
 )
@@ -29,7 +30,7 @@ func NewAuthenticator(keygen KeyGenerator) *Authenticator {
 
 func (v *Authenticator) Authenticate(data []byte) buf.Supplier {
 	hasher := hmac.New(sha1.New, v.key())
-	hasher.Write(data)
+	common.Must2(hasher.Write(data))
 	res := hasher.Sum(nil)
 	return func(b []byte) (int, error) {
 		return copy(b, res[:AuthSize]), nil
diff --git a/proxy/shadowsocks/protocol.go b/proxy/shadowsocks/protocol.go
index eb45bbf63..3dfdfc882 100644
--- a/proxy/shadowsocks/protocol.go
+++ b/proxy/shadowsocks/protocol.go
@@ -27,7 +27,7 @@ func ReadTCPSession(user *protocol.User, reader io.Reader) (*protocol.RequestHea
 	if err != nil {
 		return nil, nil, newError("failed to parse account").Base(err).AtError()
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	buffer := buf.NewLocal(512)
 	defer buffer.Release()
@@ -142,7 +142,7 @@ func WriteTCPRequest(request *protocol.RequestHeader, writer io.Writer) (buf.Wri
 	if err != nil {
 		return nil, newError("failed to parse account").Base(err).AtError()
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	if account.Cipher.IsAEAD() {
 		request.Option.Clear(RequestOptionOneTimeAuth)
@@ -211,7 +211,7 @@ func ReadTCPResponse(user *protocol.User, reader io.Reader) (buf.Reader, error)
 	if err != nil {
 		return nil, newError("failed to parse account").Base(err).AtError()
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	var iv []byte
 	if account.Cipher.IVSize() > 0 {
@@ -231,7 +231,7 @@ func WriteTCPResponse(request *protocol.RequestHeader, writer io.Writer) (buf.Wr
 	if err != nil {
 		return nil, newError("failed to parse account.").Base(err).AtError()
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	var iv []byte
 	if account.Cipher.IVSize() > 0 {
@@ -252,7 +252,7 @@ func EncodeUDPPacket(request *protocol.RequestHeader, payload []byte) (*buf.Buff
 	if err != nil {
 		return nil, newError("failed to parse account.").Base(err).AtError()
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	buffer := buf.New()
 	ivLen := account.Cipher.IVSize()
@@ -296,7 +296,7 @@ func DecodeUDPPacket(user *protocol.User, payload *buf.Buffer) (*protocol.Reques
 	if err != nil {
 		return nil, nil, newError("failed to parse account").Base(err).AtError()
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	var iv []byte
 	var authenticator *Authenticator
diff --git a/proxy/shadowsocks/server.go b/proxy/shadowsocks/server.go
index 023840d37..52434fcb5 100644
--- a/proxy/shadowsocks/server.go
+++ b/proxy/shadowsocks/server.go
@@ -21,7 +21,7 @@ import (
 type Server struct {
 	config        *ServerConfig
 	user          *protocol.User
-	account       *ShadowsocksAccount
+	account       *MemoryAccount
 	policyManager policy.Manager
 }
 
@@ -39,7 +39,7 @@ func NewServer(ctx context.Context, config *ServerConfig) (*Server, error) {
 	if err != nil {
 		return nil, newError("failed to get user account").Base(err)
 	}
-	account := rawAccount.(*ShadowsocksAccount)
+	account := rawAccount.(*MemoryAccount)
 
 	s := &Server{
 		config:  config,