diff --git a/Cargo.toml b/Cargo.toml
index 199e1d50e..2406bb10b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,6 +20,7 @@ rayon = "1.5.1"
 err-derive = "~0.3.1"
 num_cpus = "1.13.0"
 itertools = "~0.10.0"
+tempfile = "3.6.0"
 xor_name = "5.0.0"
 
   [dependencies.brotli]
diff --git a/src/chunk.rs b/src/chunk.rs
index 9d0ede4df..603353438 100644
--- a/src/chunk.rs
+++ b/src/chunk.rs
@@ -62,3 +62,12 @@ pub(crate) fn batch_chunks(bytes: Bytes) -> (usize, Vec<EncryptionBatch>) {
 
     (num_chunks, batches)
 }
+
+/// Calculate (start_position, end_position) for each chunk for the input file size
+pub(crate) fn batch_positions(data_size: usize) -> Vec<(usize, usize)> {
+    let num_chunks = get_num_chunks(data_size);
+
+    (0..num_chunks)
+        .map(|index| get_start_end_positions(data_size, index))
+        .collect()
+}
diff --git a/src/encrypt.rs b/src/encrypt.rs
index 4c10b26c9..82112586d 100644
--- a/src/encrypt.rs
+++ b/src/encrypt.rs
@@ -87,7 +87,8 @@ pub(crate) fn encrypt(batches: Vec<EncryptionBatch>) -> (DataMap, Vec<EncryptedC
     (DataMap::new(keys), chunks)
 }
 
-fn encrypt_chunk(content: Bytes, pki: (Pad, Key, Iv)) -> Result<Bytes> {
+/// Encrypt the chunk
+pub(crate) fn encrypt_chunk(content: Bytes, pki: (Pad, Key, Iv)) -> Result<Bytes> {
     let (pad, key, iv) = pki;
     let mut compressed = vec![];
     let enc_params = BrotliEncoderParams {
diff --git a/src/lib.rs b/src/lib.rs
index 5165943e0..0cefdf727 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -106,13 +106,18 @@ pub use self::{
     error::{Error, Result},
 };
 use bytes::Bytes;
+use chunk::batch_positions;
+use decrypt::decrypt_chunk;
+use encrypt::encrypt_chunk;
 use itertools::Itertools;
 use std::{
-    fs::File,
-    io::{Read, Write},
+    collections::BTreeMap,
+    fs::{File, OpenOptions},
+    io::{Read, Seek, SeekFrom, Write},
     ops::Range,
-    path::Path,
+    path::{Path, PathBuf},
 };
+use tempfile::{tempdir, TempDir};
 use xor_name::XorName;
 
 // export these because they are used in our public API.
@@ -139,6 +144,198 @@ pub struct EncryptedChunk {
     pub content: Bytes,
 }
 
+/// The streaming encryptor to carry out the encryption on fly, chunk by chunk.
+#[derive(Clone)]
+pub struct StreamSelfEncryptor {
+    // File path for the encryption target.
+    file_path: Box<PathBuf>,
+    // List of `(start_position, end_position)` for each chunk for the target file.
+    batch_positions: Vec<(usize, usize)>,
+    // Current step (i.e. chunk_index) for encryption
+    chunk_index: usize,
+    // Progressing DataMap
+    data_map: Vec<ChunkInfo>,
+    // Progressing collection of source chunks' names
+    src_hashes: BTreeMap<usize, XorName>,
+}
+
+impl StreamSelfEncryptor {
+    /// For encryption, return with an intialized streaming encryptor
+    pub fn encrypt_from_file(file_path: Box<PathBuf>) -> Result<Self> {
+        let file = File::open(&*file_path)?;
+        let metadata = file.metadata()?;
+        let file_size = metadata.len();
+
+        let batch_positions = batch_positions(file_size as usize);
+
+        Ok(StreamSelfEncryptor {
+            file_path,
+            batch_positions,
+            chunk_index: 0,
+            data_map: Vec::new(),
+            src_hashes: BTreeMap::new(),
+        })
+    }
+
+    /// Return the next encrypted chunk, if already reached the end, return with the data_map.
+    /// Note: only of the two returned options will be `Some`.
+    pub fn next_encryption(&mut self) -> Result<(Option<EncryptedChunk>, Option<DataMap>)> {
+        if self.chunk_index >= self.batch_positions.len() {
+            return Ok((None, Some(DataMap::new(self.data_map.clone()))));
+        }
+
+        let (src_hash, content) = self.read_chunk(self.chunk_index)?;
+
+        let pki = self.get_pad_key_and_iv(src_hash)?;
+        let encrypted_content = encrypt_chunk(content, pki)?;
+        let dst_hash = XorName::from_content(encrypted_content.as_ref());
+
+        let index = self.chunk_index;
+        self.chunk_index += 1;
+
+        let (start_pos, end_pos) = self.batch_positions[index];
+        self.data_map.push(ChunkInfo {
+            index,
+            dst_hash,
+            src_hash,
+            src_size: end_pos - start_pos,
+        });
+
+        Ok((
+            Some(EncryptedChunk {
+                index,
+                content: encrypted_content,
+            }),
+            None,
+        ))
+    }
+
+    fn read_chunk(&mut self, chunk_index: usize) -> Result<(XorName, Bytes)> {
+        let (start_pos, end_pos) = self.batch_positions[chunk_index];
+        let mut buffer = vec![0; end_pos - start_pos];
+
+        let mut file = File::open(&*self.file_path)?;
+
+        let _ = file.seek(SeekFrom::Start(start_pos as u64))?;
+        file.read_exact(&mut buffer)?;
+        let content = Bytes::from(buffer);
+        let src_hash = XorName::from_content(content.as_ref());
+
+        let _ = self.src_hashes.insert(chunk_index, src_hash);
+
+        Ok((src_hash, content))
+    }
+
+    fn get_pad_key_and_iv(&mut self, src_hash: XorName) -> Result<(Pad, Key, Iv)> {
+        let (n_1, n_2) = get_n_1_n_2(self.chunk_index, self.batch_positions.len());
+
+        let n_1_src_hash = self.get_src_chunk_name(n_1)?;
+        let n_2_src_hash = self.get_src_chunk_name(n_2)?;
+
+        Ok(get_pki(&src_hash, &n_1_src_hash, &n_2_src_hash))
+    }
+
+    fn get_src_chunk_name(&mut self, index: usize) -> Result<XorName> {
+        if let Some(name) = self.src_hashes.get(&index) {
+            Ok(*name)
+        } else {
+            let (src_hash, _content) = self.read_chunk(index)?;
+            Ok(src_hash)
+        }
+    }
+}
+
+/// The streaming decryptor to carry out the decryption on fly, chunk by chunk.
+pub struct StreamSelfDecryptor {
+    // File path for the decryption output.
+    file_path: Box<PathBuf>,
+    // Current step (i.e. chunk_index) for decryption
+    chunk_index: usize,
+    // Source hashes of the chunks that collected from the data_map, they shall already be sorted by index.
+    src_hashes: Vec<XorName>,
+    // Progressing collection of received encrypted chunks
+    encrypted_chunks: BTreeMap<usize, XorName>,
+    // Temp directory to hold the un-processed encrypted_chunks
+    temp_dir: TempDir,
+}
+
+impl StreamSelfDecryptor {
+    /// For decryption, return with an intialized streaming decryptor
+    pub fn decrypt_to_file(file_path: Box<PathBuf>, data_map: &DataMap) -> Result<Self> {
+        let temp_dir = tempdir()?;
+        let src_hashes = extract_hashes(data_map);
+        Ok(StreamSelfDecryptor {
+            file_path,
+            chunk_index: 0,
+            src_hashes,
+            encrypted_chunks: BTreeMap::new(),
+            temp_dir,
+        })
+    }
+
+    /// Return true if all encrypted chunk got received and file decrypted.
+    pub fn next_encrypted(&mut self, encrypted_chunk: EncryptedChunk) -> Result<bool> {
+        if encrypted_chunk.index == self.chunk_index {
+            let decrypted_content =
+                decrypt_chunk(self.chunk_index, encrypted_chunk.content, &self.src_hashes)?;
+            self.append_to_file(&decrypted_content)?;
+
+            self.chunk_index += 1;
+
+            self.drain_unprocessed()?;
+
+            if self.chunk_index == self.src_hashes.len() {
+                return Ok(true);
+            }
+        } else {
+            let chunk_name = XorName::from_content(&encrypted_chunk.content);
+
+            let file_path = self.temp_dir.path().join(hex::encode(chunk_name));
+            let mut output_file = File::create(file_path)?;
+            output_file.write_all(&encrypted_chunk.content)?;
+
+            let _ = self
+                .encrypted_chunks
+                .insert(encrypted_chunk.index, chunk_name);
+        }
+
+        Ok(false)
+    }
+
+    // If the file does not exist, it will be created. The function then writes the content to the file.
+    // If the file already exists, the content will be appended to the end of the file.
+    fn append_to_file(&self, content: &Bytes) -> std::io::Result<()> {
+        let mut file = OpenOptions::new()
+            .write(true)
+            .append(true)
+            .create(true)
+            .open(&*self.file_path)?;
+
+        file.write_all(content)?;
+
+        Ok(())
+    }
+
+    // The encrypted chunks may come in out-of-order.
+    // Drain any in-order chunks due to the recent filled in piece.
+    fn drain_unprocessed(&mut self) -> Result<()> {
+        while let Some(chunk_name) = self.encrypted_chunks.get(&self.chunk_index) {
+            let file_path = self.temp_dir.path().join(&hex::encode(chunk_name));
+            let mut chunk_file = File::open(file_path)?;
+            let mut chunk_data = Vec::new();
+            let _ = chunk_file.read_to_end(&mut chunk_data)?;
+
+            let decrypted_content =
+                decrypt_chunk(self.chunk_index, chunk_data.into(), &self.src_hashes)?;
+            self.append_to_file(&decrypted_content)?;
+
+            self.chunk_index += 1;
+        }
+
+        Ok(())
+    }
+}
+
 /// Read a file from the disk to encrypt, and output the chunks to a given output directory if presents.
 pub fn encrypt_from_file(file_path: &Path, output_dir: &Path) -> Result<(DataMap, Vec<XorName>)> {
     let mut file = File::open(file_path)?;
@@ -312,15 +509,24 @@ fn extract_hashes(data_map: &DataMap) -> Vec<XorName> {
 }
 
 fn get_pad_key_and_iv(chunk_index: usize, chunk_hashes: &[XorName]) -> (Pad, Key, Iv) {
-    let (n_1, n_2) = match chunk_index {
-        0 => (chunk_hashes.len() - 1, chunk_hashes.len() - 2),
-        1 => (0, chunk_hashes.len() - 1),
-        n => (n - 1, n - 2),
-    };
+    let (n_1, n_2) = get_n_1_n_2(chunk_index, chunk_hashes.len());
+
     let src_hash = &chunk_hashes[chunk_index];
     let n_1_src_hash = &chunk_hashes[n_1];
     let n_2_src_hash = &chunk_hashes[n_2];
 
+    get_pki(src_hash, n_1_src_hash, n_2_src_hash)
+}
+
+fn get_n_1_n_2(chunk_index: usize, total_num_chunks: usize) -> (usize, usize) {
+    match chunk_index {
+        0 => (total_num_chunks - 1, total_num_chunks - 2),
+        1 => (0, total_num_chunks - 1),
+        n => (n - 1, n - 2),
+    }
+}
+
+fn get_pki(src_hash: &XorName, n_1_src_hash: &XorName, n_2_src_hash: &XorName) -> (Pad, Key, Iv) {
     let mut pad = [0u8; PAD_SIZE];
     let mut key = [0u8; KEY_SIZE];
     let mut iv = [0u8; IV_SIZE];
diff --git a/src/tests.rs b/src/tests.rs
index 1f19478ce..de03d4624 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -8,10 +8,65 @@
 
 use crate::{
     decrypt_full_set, decrypt_range, encrypt, get_chunk_size, get_num_chunks, overlapped_chunks,
-    seek_info, test_helpers::random_bytes, DataMap, EncryptedChunk, Error, MIN_ENCRYPTABLE_BYTES,
+    seek_info, test_helpers::random_bytes, DataMap, EncryptedChunk, Error, StreamSelfDecryptor,
+    StreamSelfEncryptor, MIN_ENCRYPTABLE_BYTES,
 };
 use bytes::Bytes;
 use itertools::Itertools;
+use rand::prelude::SliceRandom;
+use std::{
+    fs::File,
+    io::{Read, Write},
+};
+use tempfile::tempdir;
+
+#[test]
+fn test_stream_self_encryptor() -> Result<(), Error> {
+    // Create a 10MB temporary file
+    let dir = tempdir()?;
+    let file_path = dir.path().join("tempfile");
+    let mut file = File::create(&file_path)?;
+    let file_size = 10 * 1024 * 1024; // 10MB
+    let data = random_bytes(file_size);
+    file.write_all(&data)?;
+
+    // Encrypt the file using StreamSelfEncryptor
+    let mut encryptor = StreamSelfEncryptor::encrypt_from_file(Box::new(file_path))?;
+    let mut encrypted_chunks = Vec::new();
+    let mut data_map = None;
+    while let Ok((chunk, map)) = encryptor.next_encryption() {
+        if let Some(c) = chunk {
+            encrypted_chunks.push(c);
+        }
+        if let Some(m) = map {
+            // Returning a data_map means file encryption is completed.
+            data_map = Some(m);
+            break;
+        }
+    }
+
+    // Shuffle the encrypted chunks
+    let mut rng = rand::thread_rng();
+    encrypted_chunks.shuffle(&mut rng);
+
+    // Decrypt the shuffled chunks using StreamSelfDecryptor
+    let decrypted_file_path = dir.path().join("decrypted");
+    let mut decryptor = StreamSelfDecryptor::decrypt_to_file(
+        Box::new(decrypted_file_path.clone()),
+        &data_map.unwrap(),
+    )?;
+    for chunk in encrypted_chunks {
+        let _ = decryptor.next_encrypted(chunk)?;
+    }
+
+    // Read the decrypted file and verify that its content matches the original data
+    let mut decrypted_file = File::open(decrypted_file_path)?;
+    let mut decrypted_data = Vec::new();
+    let _ = decrypted_file.read_to_end(&mut decrypted_data)?;
+    assert_eq!(data, decrypted_data);
+
+    Ok(())
+}
 
 #[test]
 fn write_and_read() -> Result<(), Error> {