diff --git a/common/io/encryption.go b/common/io/encryption.go
index 000558fa1..409f6b206 100644
--- a/common/io/encryption.go
+++ b/common/io/encryption.go
@@ -7,13 +7,13 @@ import (
 	"github.com/v2ray/v2ray-core/common/log"
 )
 
-// CryptionReader is a general purpose reader that applies
-// block cipher on top of a regular reader.
+// CryptionReader is a general purpose reader that applies a stream cipher on top of a regular reader.
 type CryptionReader struct {
 	stream cipher.Stream
 	reader io.Reader
 }
 
+// NewCryptionReader creates a new CryptionReader instance from given stream cipher and reader.
 func NewCryptionReader(stream cipher.Stream, reader io.Reader) *CryptionReader {
 	return &CryptionReader{
 		stream: stream,
@@ -21,8 +21,7 @@ func NewCryptionReader(stream cipher.Stream, reader io.Reader) *CryptionReader {
 	}
 }
 
-// Read reads blocks from underlying reader, the length of blocks must be
-// a multiply of BlockSize()
+// Read reads blocks from underlying reader, and crypt it. The content of blocks is modified in place.
 func (reader CryptionReader) Read(blocks []byte) (int, error) {
 	nBytes, err := reader.reader.Read(blocks)
 	if nBytes > 0 {
@@ -34,13 +33,13 @@ func (reader CryptionReader) Read(blocks []byte) (int, error) {
 	return nBytes, err
 }
 
-// Cryption writer is a general purpose of byte stream writer that applies
-// block cipher on top of a regular writer.
+// Cryption writer is a general purpose of byte stream writer that applies a stream cipher on top of a regular writer.
 type CryptionWriter struct {
 	stream cipher.Stream
 	writer io.Writer
 }
 
+// NewCryptionWriter creates a new CryptionWriter from given stream cipher and writer.
 func NewCryptionWriter(stream cipher.Stream, writer io.Writer) *CryptionWriter {
 	return &CryptionWriter{
 		stream: stream,
@@ -48,12 +47,12 @@ func NewCryptionWriter(stream cipher.Stream, writer io.Writer) *CryptionWriter {
 	}
 }
 
+// Crypt crypts the content of blocks without writing them into the underlying writer.
 func (writer CryptionWriter) Crypt(blocks []byte) {
 	writer.stream.XORKeyStream(blocks, blocks)
 }
 
-// Write writes the give blocks to underlying writer. The length of the blocks
-// must be a multiply of BlockSize()
+// Write crypts the content of blocks in place, and then writes the give blocks to underlying writer.
 func (writer CryptionWriter) Write(blocks []byte) (int, error) {
 	writer.Crypt(blocks)
 	return writer.writer.Write(blocks)