小程序总是出现诡异的解密失败问题

小程序在获取用户信息阶段总是出错，如下：

Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt
    at Decipheriv.final (internal/crypto/cipher.js:104:26)
    at WXBizDataCrypt.decryptData (/home/shike/nodejs/photo/lib/WXBizDataCrypt.js:20:25)
    at getWXData (/home/shike/nodejs/photo/routes/login.js:168:15)
    at router.post (/home/shike/nodejs/photo/routes/login.js:276:28)
    at dispatch (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:44:32)
    at next (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:45:18)
    at /home/shike/nodejs/photo/node_modules/koa-router/lib/router.js:345:16
    at dispatch (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:44:32)
    at /home/shike/nodejs/photo/node_modules/koa-compose/index.js:36:12
    at dispatch (/home/shike/nodejs/photo/node_modules/koa-router/lib/router.js:350:31)
    at dispatch (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:44:32)
    at next (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:45:18)
    at serve (/home/shike/nodejs/photo/node_modules/koa-static/index.js:47:14)
    at dispatch (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:44:32)
    at next (/home/shike/nodejs/photo/node_modules/koa-compose/index.js:45:18)
    at /home/shike/nodejs/photo/node_modules/koa-favicon/index.js:39:14

这个问题是什么原因，又怎么解决呢？搜索到了下面的链接：

https://developers.weixin.qq.com/community/develop/doc/bd11f741bdc90138ccdb51fa4d4b9896