3. 深入研究 UCenter API 之 加密与解密（转载）

 1 // $string： 明文 或 密文
 2 // $operation：DECODE表示解密,其它表示加密
 3 // $key： 密匙
 4 // $expiry：密文有效期
 5 //字符串解密加密
 6 function authcode($string, $operation = ‘DECODE‘, $key = ‘‘, $expiry = 0) {
 7      // 动态密匙长度，相同的明文会生成不同密文就是依靠动态密匙
 8     $ckey_length = 4;   // 随机密钥长度 取值 0-32;
 9                 // 加入随机密钥，可以令密文无任何规律，即便是原文和密钥完全相同，加密结果也会每次不同，增大破解难度。
10                 // 取值越大，密文变动规律越大，密文变化 = 16 的 $ckey_length 次方
11                 // 当此值为 0 时，则不产生随机密钥
12     // 密匙
13     $key = md5($key ? $key : UC_KEY);
14     // 密匙a会参与加解密
15     $keya = md5(substr($key, 0, 16));
16     // 密匙b会用来做数据完整性验证
17     $keyb = md5(substr($key, 16, 16));
18     // 密匙c用于变化生成的密文
19     $keyc = $ckey_length ? ($operation == ‘DECODE‘ ? substr($string, 0, $ckey_length): substr(md5(microtime()), -$ckey_length)) : ‘‘;
20     // 参与运算的密匙
21     $cryptkey = $keya.md5($keya.$keyc);
22     $key_length = strlen($cryptkey);   
23 
24     // 明文，前10位用来保存时间戳，解密时验证数据有效性，10到26位用来保存$keyb(密匙b)，解密时会通过这个密匙验证数据完整性
25     // 如果是解码的话，会从第$ckey_length位开始，因为密文前$ckey_length位保存 动态密匙，以保证解密正确
26     $string = $operation == ‘DECODE‘ ? base64_decode(substr($string, $ckey_length)) : sprintf(‘%010d‘, $expiry ? $expiry + time() : 0).substr(md5($string.$keyb), 0, 16).$string;
27     $string_length = strlen($string);   
28 
29     $result = ‘‘;
30     $box = range(0, 255);   
31 
32     $rndkey = array();
33     // 产生密匙簿
34     for($i = 0; $i <= 255; $i++) {
35         $rndkey[$i] = ord($cryptkey[$i % $key_length]);
36      }
37      // 用固定的算法，打乱密匙簿，增加随机性，好像很复杂，实际上对并不会增加密文的强度
38     for($j = $i = 0; $i < 256; $i++) {
39         $j = ($j + $box[$i] + $rndkey[$i]) % 256;
40         $tmp = $box[$i];
41         $box[$i] = $box[$j];
42         $box[$j] = $tmp;
43      }
44     // 核心加解密部分
45     for($a = $j = $i = 0; $i < $string_length; $i++) {
46         $a = ($a + 1) % 256;
47         $j = ($j + $box[$a]) % 256;
48         $tmp = $box[$a];
49         $box[$a] = $box[$j];
50         $box[$j] = $tmp;
51         // 从密匙簿得出密匙进行异或，再转成字符
52         $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
53      }   
54 
55     if($operation == ‘DECODE‘) {
56         // 验证数据有效性，请看未加密明文的格式
57         if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
58             return substr($result, 26);
59          } else {
60             return ‘‘;
61          }
62      } else {
63          // 把动态密匙保存在密文里，这也是为什么同样的明文，生产不同密文后能解密的原因
64          // 因为加密后的密文可能是一些特殊字符，复制过程可能会丢失，所以用base64编码
65         return $keyc.str_replace(‘=‘, ‘‘, base64_encode($result));
66      }
67 }

  1 /// <summary>
  2 /// AuthCode解码&编码
  3 /// </summary>
  4 /// <param name="sourceStr">原始字符串</param>
  5 /// <param name="operation">操作类型</param>
  6 /// <param name="keyStr">API KEY</param>
  7 /// <param name="expiry">过期时间 0代表永不过期</param>
  8 /// <returns></returns>
  9 private static string AuthCode(string sourceStr, AuthCodeMethod operation, string keyStr, int expiry = 0)
 10 {
 11     var ckeyLength = 4;
 12     var source = Encode.GetBytes(sourceStr);
 13     var key = Encode.GetBytes(keyStr);
 14 
 15     key = Md5(key);
 16 
 17     var keya = Md5(SubBytes(key, 0, 0x10));
 18     var keyb = Md5(SubBytes(key, 0x10, 0x10));
 19     var keyc = (ckeyLength > 0)
 20                     ? ((operation == AuthCodeMethod.Decode)
 21                             ? SubBytes(source, 0, ckeyLength)
 22                             : RandomBytes(ckeyLength))
 23                     : new byte[0];
 24 
 25     var cryptkey = AddBytes(keya, Md5(AddBytes(keya, keyc)));
 26     var keyLength = cryptkey.Length;
 27 
 28     if (operation == AuthCodeMethod.Decode)
 29     {
 30         while (source.Length % 4 != 0)
 31         {
 32             source = AddBytes(source, Encode.GetBytes("="));
 33         }
 34         source = Convert.FromBase64String(BytesToString(SubBytes(source, ckeyLength)));
 35     }
 36     else
 37     {
 38         source =
 39             AddBytes(
 40                 (expiry != 0
 41                         ? Encode.GetBytes((expiry + PhpTimeNow()).ToString())
 42                         : Encode.GetBytes("0000000000")),
 43                 SubBytes(Md5(AddBytes(source, keyb)), 0, 0x10), source);
 44     }
 45 
 46     var sourceLength = source.Length;
 47 
 48     var box = new int[256];
 49     for (var k = 0; k < 256; k++)
 50     {
 51         box[k] = k;
 52     }
 53 
 54     var rndkey = new int[256];
 55     for (var i = 0; i < 256; i++)
 56     {
 57         rndkey[i] = cryptkey[i % keyLength];
 58     }
 59 
 60     for (int j = 0, i = 0; i < 256; i++)
 61     {
 62         j = (j + box[i] + rndkey[i]) % 256;
 63         var tmp = box[i];
 64         box[i] = box[j];
 65         box[j] = tmp;
 66     }
 67 
 68     var result = new byte[sourceLength];
 69     for (int a = 0, j = 0, i = 0; i < sourceLength; i++)
 70     {
 71         a = (a + 1) % 256;
 72         j = (j + box[a]) % 256;
 73         var tmp = box[a];
 74         box[a] = box[j];
 75         box[j] = tmp;
 76 
 77         result[i] = (byte)(source[i] ^ (box[(box[a] + box[j]) % 256]));
 78     }
 79 
 80     if (operation == AuthCodeMethod.Decode)
 81     {
 82         var time = long.Parse(BytesToString(SubBytes(result, 0, 10)));
 83         if ((time == 0 ||
 84                 time - PhpTimeNow() > 0) &&
 85             BytesToString(SubBytes(result, 10, 16)) == BytesToString(SubBytes(Md5(AddBytes(SubBytes(result, 26), keyb)), 0, 16)))
 86         {
 87             return BytesToString(SubBytes(result, 26));
 88         }
 89         return "";
 90     }
 91     return BytesToString(keyc) + Convert.ToBase64String(result).Replace("=", "");
 92 }
 93 
 94 /// <summary>
 95 /// Byte数组转字符串
 96 /// </summary>
 97 /// <param name="b">数组</param>
 98 /// <returns></returns>
 99 public static string BytesToString(byte[] b)
100 {
101     return new string(Encode.GetChars(b));
102 }
103 
104 /// <summary>
105 /// 计算Md5
106 /// </summary>
107 /// <param name="b">byte数组</param>
108 /// <returns>计算好的字符串</returns>
109 public static byte[] Md5(byte[] b)
110 {
111     var cryptHandler = new MD5CryptoServiceProvider();
112     var hash = cryptHandler.ComputeHash(b);
113     var ret = "";
114     foreach (var a in hash)
115     {
116         if (a < 16)
117         { ret += "0" + a.ToString("x"); }
118         else
119         { ret += a.ToString("x"); }
120     }
121     return Encode.GetBytes(ret);
122 }
123 
124 /// <summary>
125 /// Byte数组相加
126 /// </summary>
127 /// <param name="bytes">数组</param>
128 /// <returns></returns>
129 public static byte[] AddBytes(params byte[][] bytes)
130 {
131     var index = 0;
132     var length = 0;
133     foreach(var b in bytes)
134     {
135         length += b.Length;
136     }
137     var result = new byte[length];
138 
139     foreach(var bs in bytes)
140     {
141         foreach (var b in bs)
142         {
143             result[index++] = b;
144         }
145     }
146     return result;
147 }
148 
149 /// <summary>
150 /// Byte数组分割
151 /// </summary>
152 /// <param name="b">数组</param>
153 /// <param name="start">开始</param>
154 /// <param name="length">结束</param>
155 /// <returns></returns>
156 public static byte[] SubBytes(byte[] b, int start, int length = int.MaxValue)
157 {
158     if (start >= b.Length) return new byte[0];
159     if (start < 0) start = 0;
160     if (length < 0) length = 0;
161     if (length>b.Length || start + length > b.Length) length = b.Length - start;
162     var result = new byte[length];
163     var index = 0;
164     for(var k = start;k< start + length;k++)
165     {
166         result[index++] = b[k];
167     }
168     return result;
169 }
170 
171 /// <summary>
172 /// 计算Php格式的当前时间
173 /// </summary>
174 /// <returns>Php格式的时间</returns>
175 public static long PhpTimeNow()
176 {
177     return DateTimeToPhpTime(DateTime.UtcNow);
178 }
179 
180 /// <summary>
181 /// PhpTime转DataTime
182 /// </summary>
183 /// <returns></returns>
184 public static DateTime PhpTimeToDateTime(long time)
185 {
186     var timeStamp = new DateTime(1970, 1, 1); //得到1970年的时间戳
187     var t = (time + 8 * 60 * 60) * 10000000 + timeStamp.Ticks;
188     return new DateTime(t);
189 }
190 
191 /// <summary>
192 /// DataTime转PhpTime
193 /// </summary>
194 /// <param name="datetime">时间</param>
195 /// <returns></returns>
196 public static long DateTimeToPhpTime(DateTime datetime)
197 {
198     var timeStamp = new DateTime(1970, 1, 1);  //得到1970年的时间戳
199     return (datetime.Ticks - timeStamp.Ticks) / 10000000;  //注意这里有时区问题，用now就要减掉8个小时
200 }
201 
202 /// <summary>
203 /// 随机字符串
204 /// </summary>
205 /// <param name="lens">长度</param>
206 /// <returns></returns>
207 public static byte[] RandomBytes(int lens)
208 {
209     var chArray = new[]
210                         {
211                             ‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘, ‘h‘, ‘j‘, ‘k‘, ‘l‘, ‘m‘, ‘n‘, ‘o‘, ‘p‘, ‘q‘,
212                             ‘r‘, ‘s‘, ‘t‘, ‘u‘, ‘v‘, ‘w‘, ‘x‘, ‘y‘, ‘z‘, ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘, ‘G‘,
213                             ‘H‘, ‘J‘, ‘K‘, ‘L‘, ‘M‘, ‘N‘, ‘O‘, ‘P‘, ‘Q‘, ‘R‘, ‘S‘, ‘T‘, ‘U‘, ‘V‘, ‘W‘, ‘X‘,
214                             ‘Y‘, ‘Z‘, ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘
215                         };
216     var length = chArray.Length;
217     var result = new byte[lens];
218     var random = new Random();
219     for (var i = 0; i < lens; i++)
220     {
221         result[i] = (byte) chArray[random.Next(length)];
222     }
223     return result;
224 }
225 
226 /// <summary>
227 /// 操作类型
228 /// </summary>
229 enum AuthCodeMethod
230 {
231     Encode,
232     Decode,
233 }