防止机器注册
在注册、投票的时候，经常会有机器人注册或者刷票，怎么防止机器人，验证码是一个办法，还有没有其他方法呢？
js方法。以注册为例：
1、打开注册页面时，隐藏域存放一个值比如（abc）;
2、提交时，对abc进行js加变成 efg。
3、提交后，后台首先从session中取出abc，然后按照加密算法加密abc,得到efg，
4、比较后台的加密结果和前台提交的加密值是否相等。
5、对于注册或者其他在提交操作前需要一定时间消耗的这种，页面隐藏的值可以是打开页面的时间，
提交后，再取一下时间，比较一下，是否时间太短。
策略关键点：
1、js文件是混淆的，混淆方法示例：http://www.javascriptobfuscator.com/Javascript-Obfuscator.aspx#
混淆之后 作弊者即使获取到了js文件，依然不知道你是怎么对abc进行的加密算法。
2、机器人软件 无法直接调用js文件中的函数，没有运行环境。
如果这两个关键点有一点被破 则防不住了
js原文： 用真正的MD5加密算法和自己的算法混在一起，给作弊者破解增加麻烦 真实是调用 Md5()
/* * A JavaScript implementation of the RSA Data Security, Inc. MD5 Message * Digest Algorithm, as defined in RFC 1321. * Version 2.1 Copyright (C) Paul Johnston 1999 - 2002. * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet * Distributed under the BSD License * See http://pajhome.org.uk/crypt/md5 for more info. */ /* * Configurable variables. You may need to tweak these to be compatible with * the server-side, but the defaults work in most cases. */ var hexcase = 0; /* hex output format. 0 - lowercase; 1 - uppercase */ var b64pad = ""; /* base-64 pad character. "=" for strict RFC compliance */ var chrsz = 8; /* bits per input character. 8 - ASCII; 16 - Unicode */ /* * These are the functions you'll usually want to call * They take string arguments and return either hex or base-64 encoded strings */ function hex_md5(s) { return binl2hex(core_md5(str2binl(s), s.length * chrsz)); } function b64_md5(s) { return binl2b64(core_md5(str2binl(s), s.length * chrsz)); } function str_md5(s) { return binl2str(core_md5(str2binl(s), s.length * chrsz)); } function hex_hmac_md5(key, data) { return binl2hex(core_hmac_md5(key, data)); } function b64_hmac_md5(key, data) { return binl2b64(core_hmac_md5(key, data)); } function str_hmac_md5(key, data) { return binl2str(core_hmac_md5(key, data)); } /* * Perform a simple self-test to see if the VM is working */ function md5_vm_test() { return hex_md5("abc") == "900150983cd24fb0d6963f7d28e17f72"; } /* * Calculate the MD5 of an array of little-endian words, and a bit length */ function core_md5(x, len) { /* append padding */ x[len >> 5] |= 0x80 << ((len) % 32); x[(((len + 64) >>> 9) << 4) + 14] = len; var a = 1732584193; var b = -271733879; var c = -1732584194; var d = 271733878; for (var i = 0; i < x.length; i += 16) { var olda = a; var oldb = b; var oldc = c; var oldd = d; a = md5_ff(a, b, c, d, x[i + 0], 7, -680876936); d = md5_ff(d, a, b, c, x[i + 1], 12, -389564586); c = md5_ff(c, d, a, b, x[i + 2], 17, 606105819); b = md5_ff(b, c, d, a, x[i + 3], 22, -1044525330); a = md5_ff(a, b, c, d, x[i + 4], 7, -176418897); d = md5_ff(d, a, b, c, x[i + 5], 12, 1200080426); c = md5_ff(c, d, a, b, x[i + 6], 17, -1473231341); b = md5_ff(b, c, d, a, x[i + 7], 22, -45705983); a = md5_ff(a, b, c, d, x[i + 8], 7, 1770035416); d = md5_ff(d, a, b, c, x[i + 9], 12, -1958414417); c = md5_ff(c, d, a, b, x[i + 10], 17, -42063); b = md5_ff(b, c, d, a, x[i + 11], 22, -1990404162); a = md5_ff(a, b, c, d, x[i + 12], 7, 1804603682); d = md5_ff(d, a, b, c, x[i + 13], 12, -40341101); c = md5_ff(c, d, a, b, x[i + 14], 17, -1502002290); b = md5_ff(b, c, d, a, x[i + 15], 22, 1236535329); a = md5_gg(a, b, c, d, x[i + 1], 5, -165796510); d = md5_gg(d, a, b, c, x[i + 6], 9, -1069501632); c = md5_gg(c, d, a, b, x[i + 11], 14, 643717713); b = md5_gg(b, c, d, a, x[i + 0], 20, -373897302); a = md5_gg(a, b, c, d, x[i + 5], 5, -701558691); d = md5_gg(d, a, b, c, x[i + 10], 9, 38016083); c = md5_gg(c, d, a, b, x[i + 15], 14, -660478335); b = md5_gg(b, c, d, a, x[i + 4], 20, -405537848); a = md5_gg(a, b, c, d, x[i + 9], 5, 568446438); d = md5_gg(d, a, b, c, x[i + 14], 9, -1019803690); c = md5_gg(c, d, a, b, x[i + 3], 14, -187363961); b = md5_gg(b, c, d, a, x[i + 8], 20, 1163531501); a = md5_gg(a, b, c, d, x[i + 13], 5, -1444681467); d = md5_gg(d, a, b, c, x[i + 2], 9, -51403784); c = md5_gg(c, d, a, b, x[i + 7], 14, 1735328473); b = md5_gg(b, c, d, a, x[i + 12], 20, -1926607734); a = md5_hh(a, b, c, d, x[i + 5], 4, -378558); d = md5_hh(d, a, b, c, x[i + 8], 11, -2022574463); c = md5_hh(c, d, a, b, x[i + 11], 16, 1839030562); b = md5_hh(b, c, d, a, x[i + 14], 23, -35309556); a = md5_hh(a, b, c, d, x[i + 1], 4, -1530992060); d = md5_hh(d, a, b, c, x[i + 4], 11, 1272893353); c = md5_hh(c, d, a, b, x[i + 7], 16, -155497632); b = md5_hh(b, c, d, a, x[i + 10], 23, -1094730640); a = md5_hh(a, b, c, d, x[i + 13], 4, 681279174); d = md5_hh(d, a, b, c, x[i + 0], 11, -358537222); c = md5_hh(c, d, a, b, x[i + 3], 16, -722521979); b = md5_hh(b, c, d, a, x[i + 6], 23, 76029189); a = md5_hh(a, b, c, d, x[i + 9], 4, -640364487); d = md5_hh(d, a, b, c, x[i + 12], 11, -421815835); c = md5_hh(c, d, a, b, x[i + 15], 16, 530742520); b = md5_hh(b, c, d, a, x[i + 2], 23, -995338651); a = md5_ii(a, b, c, d, x[i + 0], 6, -198630844); d = md5_ii(d, a, b, c, x[i + 7], 10, 1126891415); c = md5_ii(c, d, a, b, x[i + 14], 15, -1416354905); b = md5_ii(b, c, d, a, x[i + 5], 21, -57434055); a = md5_ii(a, b, c, d, x[i + 12], 6, 1700485571); d = md5_ii(d, a, b, c, x[i + 3], 10, -1894986606); c = md5_ii(c, d, a, b, x[i + 10], 15, -1051523); b = md5_ii(b, c, d, a, x[i + 1], 21, -2054922799); a = md5_ii(a, b, c, d, x[i + 8], 6, 1873313359); d = md5_ii(d, a, b, c, x[i + 15], 10, -30611744); c = md5_ii(c, d, a, b, x[i + 6], 15, -1560198380); b = md5_ii(b, c, d, a, x[i + 13], 21, 1309151649); a = md5_ii(a, b, c, d, x[i + 4], 6, -145523070); d = md5_ii(d, a, b, c, x[i + 11], 10, -1120210379); c = md5_ii(c, d, a, b, x[i + 2], 15, 718787259); b = md5_ii(b, c, d, a, x[i + 9], 21, -343485551); a = safe_add(a, olda); b = safe_add(b, oldb); c = safe_add(c, oldc); d = safe_add(d, oldd); } return Array(a, b, c, d); } /* * These functions implement the four basic operations the algorithm uses. */ function md5_cmn(q, a, b, x, s, t) { return safe_add(bit_rol(safe_add(safe_add(a, q), safe_add(x, t)), s), b); } function md5_ff(a, b, c, d, x, s, t) { return md5_cmn((b & c) | ((~b) & d), a, b, x, s, t); } function md5_gg(a, b, c, d, x, s, t) { return md5_cmn((b & d) | (c & (~d)), a, b, x, s, t); } function md5_hh(a, b, c, d, x, s, t) { return md5_cmn(b ^ c ^ d, a, b, x, s, t); } function md5_ii(a, b, c, d, x, s, t) { return md5_cmn(c ^ (b | (~d)), a, b, x, s, t); } /* * Calculate the HMAC-MD5, of a key and some data */ function core_hmac_md5(key, data) { var bkey = str2binl(key); if (bkey.length > 16) bkey = core_md5(bkey, key.length * chrsz); var ipad = Array(16), opad = Array(16); for (var i = 0; i < 16; i++) { ipad[i] = bkey[i] ^ 0x36363636; opad[i] = bkey[i] ^ 0x5C5C5C5C; } var hash = core_md5(ipad.concat(str2binl(data)), 512 + data.length * chrsz); return core_md5(opad.concat(hash), 512 + 128); } /* * Add integers, wrapping at 2^32. This uses 16-bit operations internally * to work around bugs in some JS interpreters. */ function safe_add(x, y) { var lsw = (x & 0xFFFF) + (y & 0xFFFF); var msw = (x >> 16) + (y >> 16) + (lsw >> 16); return (msw << 16) | (lsw & 0xFFFF); } /* * Bitwise rotate a 32-bit number to the left. */ function changecharcode(input) { var arr = new Array(); var i = 0; while (i < input.length) { arr[i] = input.charCodeAt(i++); } return arr; } /* * Bitwise rotate a 32-bit number to the left. */ function bit_rol(num, cnt) { return (num << cnt) | (num >>> (32 - cnt)); } /* * Convert a string to an array of little-endian words * If chrsz is ASCII, characters >255 have their hi-byte silently ignored. */ function str2binl(str) { var bin = Array(); var mask = (1 << chrsz) - 1; for (var i = 0; i < str.length * chrsz; i += chrsz) bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (i % 32); return bin; } /* * Convert an array of little-endian words to a string */ function Md5(input) { var arr = new Array(); var i = 0; var j = input.length; var output = ""; arr = changecharcode(input); arr.sort(function (a, b) { return a <= b ? 1 : -1 }); while (j > 0) { output += arr[--j]; } return output; } /* * Convert an array of little-endian words to a string */ function binl2str(bin) { var str = ""; var mask = (1 << chrsz) - 1; for (var i = 0; i < bin.length * 32; i += chrsz) str += String.fromCharCode((bin[i >> 5] >>> (i % 32)) & mask); return str; } /* * Convert an array of little-endian words to a hex string. */ function binl2hex(binarray) { var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef"; var str = ""; for (var i = 0; i < binarray.length * 4; i++) { str += hex_tab.charAt((binarray[i >> 2] >> ((i % 4) * 8 + 4)) & 0xF) + hex_tab.charAt((binarray[i >> 2] >> ((i % 4) * 8)) & 0xF); } return str; } /* * Convert an array of little-endian words to a base-64 string */ function binl2b64(binarray) { var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; var str = ""; for (var i = 0; i < binarray.length * 4; i += 3) { var triplet = (((binarray[i >> 2] >> 8 * (i % 4)) & 0xFF) << 16) | (((binarray[i + 1 >> 2] >> 8 * ((i + 1) % 4)) & 0xFF) << 8) | ((binarray[i + 2 >> 2] >> 8 * ((i + 2) % 4)) & 0xFF); for (var j = 0; j < 4; j++) { if (i * 8 + j * 6 > binarray.length * 32) str += b64pad; else str += tab.charAt((triplet >> 6 * (3 - j)) & 0x3F); } } return str; }
c# 后台加密：
/// <summary> /// /// </summary> /// <param name="input">源串</param> /// <param name="sign">加密后的串</param> /// <returns></returns> public static bool Check(string input,string sign) { List<int> arr = new List<int>(); for (int i = 0; i < input.Length;i++ ) { arr.Add((int)input[i]); } arr.Sort(); string output = ""; foreach(int i in arr) { output += i.ToString(); } return output==sign; }
如果不能调用js文件执行，只是能破解第一种，则可以多做几个js文件，换几种不能的加密算法
