字数：6944
主要为了设定一个门槛——随意调用服务端的接口（无法彻底杜绝），特别是网路拦截者无法重放，即使截获了，由于是https加密也无法得知md5的因子。 下述script代码可以直接在chrome里看效果，内容中appkey是通信双方都知晓的内容，uuid是为了防止重放，timestamp是为了验证有效期。
<script>
!function(n) {
"use strict";
function t(n, t) {
var r = (65535 & n) + (65535 & t);
return (n >> 16) + (t >> 16) + (r >> 16) << 16 | 65535 & r
}
function r(n, t) {
return n << t | n >>> 32 - t
}
function e(n, e, o, u, c, f) {
return t(r(t(t(e, n), t(u, f)), c), o)
}
function o(n, t, r, o, u, c, f) {
return e(t & r | ~t & o, n, t, u, c, f)
}
function u(n, t, r, o, u, c, f) {
return e(t & o | r & ~o, n, t, u, c, f)
}
function c(n, t, r, o, u, c, f) {
return e(t ^ r ^ o, n, t, u, c, f)
}
function f(n, t, r, o, u, c, f) {
return e(r ^ (t | ~o), n, t, u, c, f)
}
function i(n, r) {
n[r >> 5] |= 128 << r % 32,
n[14 + (r + 64 >>> 9 << 4)] = r;
var e, i, a, d, h, l = 1732584193, g = -271733879, v = -1732584194, m = 271733878;
for (e = 0; e < n.length; e += 16)
i = l,
a = g,
d = v,
h = m,
g = f(g = f(g = f(g = f(g = c(g = c(g = c(g = c(g = u(g = u(g = u(g = u(g = o(g = o(g = o(g = o(g, v = o(v, m = o(m, l = o(l, g, v, m, n[e], 7, -680876936), g, v, n[e + 1], 12, -389564586), l, g, n[e + 2], 17, 606105819), m, l, n[e + 3], 22, -1044525330), v = o(v, m = o(m, l = o(l, g, v, m, n[e + 4], 7, -176418897), g, v, n[e + 5], 12, 1200080426), l, g, n[e + 6], 17, -1473231341), m, l, n[e + 7], 22, -45705983), v = o(v, m = o(m, l = o(l, g, v, m, n[e + 8], 7, 1770035416), g, v, n[e + 9], 12, -1958414417), l, g, n[e + 10], 17, -42063), m, l, n[e + 11], 22, -1990404162), v = o(v, m = o(m, l = o(l, g, v, m, n[e + 12], 7, 1804603682), g, v, n[e + 13], 12, -40341101), l, g, n[e + 14], 17, -1502002290), m, l, n[e + 15], 22, 1236535329), v = u(v, m = u(m, l = u(l, g, v, m, n[e + 1], 5, -165796510), g, v, n[e + 6], 9, -1069501632), l, g, n[e + 11], 14, 643717713), m, l, n[e], 20, -373897302), v = u(v, m = u(m, l = u(l, g, v, m, n[e + 5], 5, -701558691), g, v, n[e + 10], 9, 38016083), l, g, n[e + 15], 14, -660478335), m, l, n[e + 4], 20, -405537848), v = u(v, m = u(m, l = u(l, g, v, m, n[e + 9], 5, 568446438), g, v, n[e + 14], 9, -1019803690), l, g, n[e + 3], 14, -187363961), m, l, n[e + 8], 20, 1163531501), v = u(v, m = u(m, l = u(l, g, v, m, n[e + 13], 5, -1444681467), g, v, n[e + 2], 9, -51403784), l, g, n[e + 7], 14, 1735328473), m, l, n[e + 12], 20, -1926607734), v = c(v, m = c(m, l = c(l, g, v, m, n[e + 5], 4, -378558), g, v, n[e + 8], 11, -2022574463), l, g, n[e + 11], 16, 1839030562), m, l, n[e + 14], 23, -35309556), v = c(v, m = c(m, l = c(l, g, v, m, n[e + 1], 4, -1530992060), g, v, n[e + 4], 11, 1272893353), l, g, n[e + 7], 16, -155497632), m, l, n[e + 10], 23, -1094730640), v = c(v, m = c(m, l = c(l, g, v, m, n[e + 13], 4, 681279174), g, v, n[e], 11, -358537222), l, g, n[e + 3], 16, -722521979), m, l, n[e + 6], 23, 76029189), v = c(v, m = c(m, l = c(l, g, v, m, n[e + 9], 4, -640364487), g, v, n[e + 12], 11, -421815835), l, g, n[e + 15], 16, 530742520), m, l, n[e + 2], 23, -995338651), v = f(v, m = f(m, l = f(l, g, v, m, n[e], 6, -198630844), g, v, n[e + 7], 10, 1126891415), l, g, n[e + 14], 15, -1416354905), m, l, n[e + 5], 21, -57434055), v = f(v, m = f(m, l = f(l, g, v, m, n[e + 12], 6, 1700485571), g, v, n[e + 3], 10, -1894986606), l, g, n[e + 10], 15, -1051523), m, l, n[e + 1], 21, -2054922799), v = f(v, m = f(m, l = f(l, g, v, m, n[e + 8], 6, 1873313359), g, v, n[e + 15], 10, -30611744), l, g, n[e + 6], 15, -1560198380), m, l, n[e + 13], 21, 1309151649), v = f(v, m = f(m, l = f(l, g, v, m, n[e + 4], 6, -145523070), g, v, n[e + 11], 10, -1120210379), l, g, n[e + 2], 15, 718787259), m, l, n[e + 9], 21, -343485551),
l = t(l, i),
g = t(g, a),
v = t(v, d),
m = t(m, h);
return [l, g, v, m]
}
function a(n) {
var t, r = "", e = 32 * n.length;
for (t = 0; t < e; t += 8)
r += String.fromCharCode(n[t >> 5] >>> t % 32 & 255);
return r
}
function d(n) {
var t, r = [];
for (r[(n.length >> 2) - 1] = void 0,
t = 0; t < r.length; t += 1)
r[t] = 0;
var e = 8 * n.length;
for (t = 0; t < e; t += 8)
r[t >> 5] |= (255 & n.charCodeAt(t / 8)) << t % 32;
return r
}
function h(n) {
return a(i(d(n), 8 * n.length))
}
function l(n, t) {
var r, e, o = d(n), u = [], c = [];
for (u[15] = c[15] = void 0,
o.length > 16 && (o = i(o, 8 * n.length)),
r = 0; r < 16; r += 1)
u[r] = 909522486 ^ o[r],
c[r] = 1549556828 ^ o[r];
return e = i(u.concat(d(t)), 512 + 8 * t.length),
a(i(c.concat(e), 640))
}
function g(n) {
var t, r, e = "";
for (r = 0; r < n.length; r += 1)
t = n.charCodeAt(r),
e += "0123456789abcdef".charAt(t >>> 4 & 15) + "0123456789abcdef".charAt(15 & t);
return e
}
function v(n) {
return unescape(encodeURIComponent(n))
}
function m(n) {
return h(v(n))
}
function p(n) {
return g(m(n))
}
function s(n, t) {
return l(v(n), v(t))
}
function C(n, t) {
return g(s(n, t))
}
function A(n, t, r) {
return t ? r ? s(t, n) : C(t, n) : r ? m(n) : p(n)
}
"function" == typeof define && define.amd ? define(function() {
return A
}) : "object" == typeof module && module.exports ? module.exports = A : n.md5 = A
}(this);
//# sourceMappingURL=md5.min.js.map
//https://www.hostingadvice.com/how-to/javascript-md5-library/
//https://www.cnblogs.com/pangguoming/p/7090906.html
//https://www.cnblogs.com/lipcblog/p/6725347.html
function uuid() {
var s = [];
var hexDigits = "0123456789abcdef";
for (var i = 0; i < 36; i++) {
s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
}
s[14] = "4"; // bits 12-15 of the time_hi_and_version field to 0010
s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1); // bits 6-7 of the clock_seq_hi_and_reserved to 01
s[8] = s[13] = s[18] = s[23] = "-";
var uuid = s.join("");
return uuid;
}
var id = uuid();
var timestamp = new Date().getTime();
console.log(md5("appkey" + id + timestamp) + ',' + id + ',' + timestamp);
console.log("source: 1542104282516vRd1q1g12euvBpEb25fvwuju")
console.log("expected: c533723c878f045b88970ee0160d52d1,1542104282516")
console.log("actual: " + md5("1542104282516vRd1q1g12euvBpEb25fvwuju"));
</script>
这个就是Valine评论插件里的X-LC-Sign内容的产生方法。另外，还有一个非对称加密的开源方案，在这里， 不管哪一种方案，都存在一个保管的问题，如果保管的问题解决了，只是验证调用者的话，用第一种方法更简单。