diff --git a/RSA.java b/RSA.java
new file mode 100644
index 0000000000000000000000000000000000000000..9d0618694ae3ed5379ff12f5b57122d4a74e14fc
--- /dev/null
+++ b/RSA.java
@@ -0,0 +1,75 @@
+public class RSA {
+    private final PublicKey publicKey;
+    private final PrivateKey privateKey;
+
+    /**
+     * 自定义公钥和私钥
+     * @param n 公钥和私钥的n
+     * @param e 公钥的e
+     * @param d 私钥的d
+     */
+    public RSA(BigInteger n,BigInteger e,BigInteger d){
+        RSAPublicKeySpec publicKeySpec = new RSAPublicKeySpec(n, e);
+        RSAPrivateKeySpec privateKeySpec = new RSAPrivateKeySpec(n, d);
+        try {
+            KeyFactory rsa = KeyFactory.getInstance("RSA");
+            publicKey = rsa.generatePublic(publicKeySpec);
+            privateKey = rsa.generatePrivate(privateKeySpec);
+        } catch (Exception ex) {
+            throw new RuntimeException(ex);
+        }
+    }
+
+    /**
+     * 指定密钥大小生成公钥和私钥
+     * @param keySize 密钥大小
+     */
+    public RSA(int keySize){
+        try {
+            KeyPairGenerator keyGenerator = KeyPairGenerator.getInstance("RSA");
+            keyGenerator.initialize(keySize);
+            KeyPair keyPair = keyGenerator.generateKeyPair();
+            publicKey = keyPair.getPublic();
+            privateKey = keyPair.getPrivate();
+            System.out.println("publicKey = " + Base64.getEncoder().encodeToString(publicKey.getEncoded()));
+            System.out.println("privateKey = " + Base64.getEncoder().encodeToString(privateKey.getEncoded()));
+        } catch (NoSuchAlgorithmException ex) {
+            throw new RuntimeException(ex);
+        }
+    }
+
+    /**
+     * 获取密文
+     * @param plainText 明文
+     * @return 密文
+     */
+    public String encode(String plainText){
+        try {
+            Cipher cipher = getInstance("RSA");
+            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
+            byte[] bytes = cipher.doFinal(plainText.getBytes());
+            return Base64.getEncoder().encodeToString(bytes);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * 获取明文
+     * @param cipherText 密文
+     * @return 明文
+     */
+    public String decode(String cipherText){
+        try {
+            Cipher cipher = getInstance("RSA");
+            cipher.init(Cipher.DECRYPT_MODE, privateKey);
+            byte[] bytes = cipher.doFinal(Base64.getDecoder().decode(cipherText));
+            return new String(bytes);
+        } catch (Exception ex) {
+            throw new RuntimeException(ex);
+        }
+    }
+
+
+
+}