diff --git a/src/Pay/Encryptor.ts b/src/Pay/Encryptor.ts
new file mode 100644
index 0000000..dca1236
--- /dev/null
+++ b/src/Pay/Encryptor.ts
@@ -0,0 +1,31 @@
+'use strict';
+import { PrivateKey } from "../Core/Support/PrivateKey";
+import { PublicKey } from "../Core/Support/PublicKey";
+import RSA from "../Core/Support/RSA";
+
+class Encryptor extends RSA {
+  protected publicCert: PublicKey;
+  protected privateCert: PrivateKey;
+
+  /**
+   * 设置加密机所需的公私密钥
+   * @param publicCert PublicKey封装的公钥
+   * @param privateCert PrivateKey封装的私钥
+   */
+  setCerts(publicCert: PublicKey, privateCert: PrivateKey) {
+    this.publicCert = publicCert;
+    this.privateCert = privateCert;
+    this.setPublicKey(publicCert.toString());
+    this.setPrivateKey(privateCert.toString());
+  }
+
+  /**
+   * 获取公钥的序列号
+   */
+  getSerialNo(): string {
+    return this.publicCert.getSerialNo();
+  }
+
+}
+
+export = Encryptor;
diff --git a/src/Pay/Utils.ts b/src/Pay/Utils.ts
index e421cc6..cfb176b 100644
--- a/src/Pay/Utils.ts
+++ b/src/Pay/Utils.ts
@@ -5,6 +5,7 @@ import RSA from '../Core/Support/RSA';
 import { createHash, createHmac, getTimestamp, randomString } from '../Core/Support/Utils';
 import { PayAppConfig, PayBridgeConfig, PaySdkConfig } from '../Types/global';
 import MerchantInterface from './Contracts/MerchantInterface';
+import Encryptor from './Encryptor';
 
 class Utils
 {
@@ -30,13 +31,12 @@ class Utils
    * @returns
    */
   async getEncryptor(platformCert: PublicKey = null) {
-    let rsa = new RSA;
     if (!platformCert || !(platformCert instanceof PublicKey)) {
       platformCert = await this.getPlatformCert();
     }
-    rsa.setPublicKey(platformCert.toString());
-    rsa.setPrivateKey(this.merchant.getPrivateKey().toString());
-    return rsa;
+    let encryptor = new Encryptor;
+    encryptor.setCerts(platformCert, this.merchant.getPrivateKey());
+    return encryptor;
   }
 
   /**
diff --git a/test/Pay/Utils.test.js b/test/Pay/Utils.test.js
index 53d004b..5a28720 100644
--- a/test/Pay/Utils.test.js
+++ b/test/Pay/Utils.test.js
@@ -30,10 +30,9 @@ class TestUnit extends BaseTestUnit {
 
     it('Should encrypt and decrypt correctly', async () => {
       let data = 'Abc123';
-      let cert = await utils.getPlatformCert();
-      let encryptor = await utils.getEncryptor(cert);
+      let encryptor = await utils.getEncryptor();
       let ciphertext = encryptor.encrypt(data);
-      this.assert.strictEqual(cert.getSerialNo(), '0DC0DF83');
+      this.assert.strictEqual(encryptor.getSerialNo(), '0DC0DF83');
 
       let plaintext = encryptor.decrypt(ciphertext);
       this.assert.strictEqual(plaintext, data);