feat: update readme

README.md

@@ -5,3 +5,29 @@
 In stage 1 we only encrypt file content, the file name is not encrypted.
 
 In the future we are going to encrypt the file name also.
+
+
+<br>
+
+AES-CTR algorithm is show as: https://git.hatter.ink/hatter/simple-rust-tests/src/branch/master/__crypto/aes_ctr_test/src/main.rs
+
+
+Algorithm  is shown as below:
+```rust
+let key = <Your AES encryption key>;
+let iv = <Random 8 bytes>;
+
+let plaintext = <Plaintext bytes>;
+let ciphertext = <plaintext.len() bytes>;
+let plaintext_block_count = ceil(plaintext / 16);
+
+for counter in 0..plaintext_block_count {
+    let iv_and_counter = iv + counter.to_be_bytes();
+    let encrytped_iv_and_counter = aes_encrypt(key, iv_and_counter);
+
+    for i in 0..encrytped_iv_and_counter {
+        ciphertext[counter * 16 + i] = encrytped_iv_and_counter[i] ^ plaintext[counter * 16 + i];
+    }
+}
+```
+