初始化

common/js/WXBizDataCrypt.js

@@ -0,0 +1,35 @@
+var crypto = require('crypto')
+
+function WXBizDataCrypt(appId, sessionKey) {
+  this.appId = appId
+  this.sessionKey = sessionKey
+}
+
+WXBizDataCrypt.prototype.decryptData = function (encryptedData, iv) {
+  // base64 decode
+  var sessionKey = new Buffer(this.sessionKey, 'base64')
+  encryptedData = new Buffer(encryptedData, 'base64')
+  iv = new Buffer(iv, 'base64')
+
+  try {
+     // 解密
+    var decipher = crypto.createDecipheriv('aes-128-cbc', sessionKey, iv)
+    // 设置自动 padding 为 true，删除填充补位
+    decipher.setAutoPadding(true)
+    var decoded = decipher.update(encryptedData, 'binary', 'utf8')
+    decoded += decipher.final('utf8')
+    
+    decoded = JSON.parse(decoded)
+
+  } catch (err) {
+    throw new Error('Illegal Buffer')
+  }
+
+  if (decoded.watermark.appid !== this.appId) {
+    throw new Error('Illegal Buffer')
+  }
+
+  return decoded
+}
+
+module.exports = WXBizDataCrypt