1

tool/WXBizDataCrypt.js

@@ -0,0 +1,34 @@
+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;