内容简介:MD5是一种信息-摘要算法,一种单向函数算法(也就是HASH算法)。将不同输入长度的信息进行散列计算,得到固定长度的输出。它的主要特点是,不可逆和唯一性。即不能由结果计算出输入值;且不同的输入值计算得到的固定长度输出是唯一的。目前使用的面向对象编程语言中,基本都有类库实现好的MD5方法可以使用。为了更好地弄清楚内部运行原理,参考了一些实现算法,如下,使用C#自己实现MD5算法。上代码看看,
MD5是一种信息-摘要算法,一种单向函数算法(也就是HASH算法)。将不同输入长度的信息进行散列计算,得到固定长度的输出。它的主要特点是,不可逆
和唯一性。即不能由结果计算出输入值;且不同的输入值计算得到的固定长度输出是唯一的。
目前使用的面向对象编程语言中,基本都有类库实现好的MD5方法可以使用。为了更好地弄清楚内部运行原理,参考了一些实现算法,如下,使用C#自己实现MD5算法。上代码看看,
public class MyMD5 { //static state variables private static UInt32 A; private static UInt32 B; private static UInt32 C; private static UInt32 D; //number of bits to rotate in tranforming private const int S11 = 7; private const int S12 = 12; private const int S13 = 17; private const int S14 = 22; private const int S21 = 5; private const int S22 = 9; private const int S23 = 14; private const int S24 = 20; private const int S31 = 4; private const int S32 = 11; private const int S33 = 16; private const int S34 = 23; private const int S41 = 6; private const int S42 = 10; private const int S43 = 15; private const int S44 = 21; /* F, G, H and I are basic MD5 functions. * 四个非线性函数: * * F(X,Y,Z) =(X&Y)|((~X)&Z) * G(X,Y,Z) =(X&Z)|(Y&(~Z)) * H(X,Y,Z) =X^Y^Z * I(X,Y,Z)=Y^(X|(~Z)) * * (&与,|或,~非,^异或) */ private static UInt32 F(UInt32 x, UInt32 y, UInt32 z) { return (x & y) | ((~x) & z); } private static UInt32 G(UInt32 x, UInt32 y, UInt32 z) { return (x & z) | (y & (~z)); } private static UInt32 H(UInt32 x, UInt32 y, UInt32 z) { return x ^ y ^ z; } private static UInt32 I(UInt32 x, UInt32 y, UInt32 z) { return y ^ (x | (~z)); } /* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4. * Rotation is separate from addition to prevent recomputation. */ private static void FF(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti) { a = a + F(b, c, d) + mj + ti; a = a << s | a >> (32 - s); a += b; } private static void GG(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti) { a = a + G(b, c, d) + mj + ti; a = a << s | a >> (32 - s); a += b; } private static void HH(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti) { a = a + H(b, c, d) + mj + ti; a = a << s | a >> (32 - s); a += b; } private static void II(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti) { a = a + I(b, c, d) + mj + ti; a = a << s | a >> (32 - s); a += b; } private static void MD5_Init() { A = 0x67452301; //in memory, this is 0x01234567 B = 0xefcdab89; //in memory, this is 0x89abcdef C = 0x98badcfe; //in memory, this is 0xfedcba98 D = 0x10325476; //in memory, this is 0x76543210 } private static UInt32[] MD5_Append(byte[] input) { int zeros = 0; int ones = 1; int size = 0; int n = input.Length; int m = n % 64; if (m < 56) { zeros = 55 - m; size = n - m + 64; } else if (m == 56) { zeros = 0; ones = 0; size = n + 8; } else { zeros = 63 - m + 56; size = n + 64 - m + 64; } ArrayList bs = new ArrayList(input); if (ones == 1) { bs.Add((byte)0x80); // 0x80 = $10000000 } for (int i = 0; i < zeros; i++) { bs.Add((byte)0); } UInt64 N = (UInt64)n * 8; byte h1 = (byte)(N & 0xFF); byte h2 = (byte)((N >> 8) & 0xFF); byte h3 = (byte)((N >> 16) & 0xFF); byte h4 = (byte)((N >> 24) & 0xFF); byte h5 = (byte)((N >> 32) & 0xFF); byte h6 = (byte)((N >> 40) & 0xFF); byte h7 = (byte)((N >> 48) & 0xFF); byte h8 = (byte)(N >> 56); bs.Add(h1); bs.Add(h2); bs.Add(h3); bs.Add(h4); bs.Add(h5); bs.Add(h6); bs.Add(h7); bs.Add(h8); byte[] ts = (byte[])bs.ToArray(typeof(byte)); /* Decodes input (byte[]) into output (UInt32[]). Assumes len is * a multiple of 4. */ UInt32[] output = new UInt32[size / 4]; for (Int64 i = 0, j = 0; i < size; j++, i += 4) { output[j] = (UInt32)(ts[i] | ts[i + 1] << 8 | ts[i + 2] << 16 | ts[i + 3] << 24); } return output; } private static UInt32[] MD5_Trasform(UInt32[] x) { UInt32 a, b, c, d; for (int k = 0; k < x.Length; k += 16) { a = A; b = B; c = C; d = D; /* Round 1 */ FF(ref a, b, c, d, x[k + 0], S11, 0xd76aa478); /* 1 */ FF(ref d, a, b, c, x[k + 1], S12, 0xe8c7b756); /* 2 */ FF(ref c, d, a, b, x[k + 2], S13, 0x242070db); /* 3 */ FF(ref b, c, d, a, x[k + 3], S14, 0xc1bdceee); /* 4 */ FF(ref a, b, c, d, x[k + 4], S11, 0xf57c0faf); /* 5 */ FF(ref d, a, b, c, x[k + 5], S12, 0x4787c62a); /* 6 */ FF(ref c, d, a, b, x[k + 6], S13, 0xa8304613); /* 7 */ FF(ref b, c, d, a, x[k + 7], S14, 0xfd469501); /* 8 */ FF(ref a, b, c, d, x[k + 8], S11, 0x698098d8); /* 9 */ FF(ref d, a, b, c, x[k + 9], S12, 0x8b44f7af); /* 10 */ FF(ref c, d, a, b, x[k + 10], S13, 0xffff5bb1); /* 11 */ FF(ref b, c, d, a, x[k + 11], S14, 0x895cd7be); /* 12 */ FF(ref a, b, c, d, x[k + 12], S11, 0x6b901122); /* 13 */ FF(ref d, a, b, c, x[k + 13], S12, 0xfd987193); /* 14 */ FF(ref c, d, a, b, x[k + 14], S13, 0xa679438e); /* 15 */ FF(ref b, c, d, a, x[k + 15], S14, 0x49b40821); /* 16 */ /* Round 2 */ GG(ref a, b, c, d, x[k + 1], S21, 0xf61e2562); /* 17 */ GG(ref d, a, b, c, x[k + 6], S22, 0xc040b340); /* 18 */ GG(ref c, d, a, b, x[k + 11], S23, 0x265e5a51); /* 19 */ GG(ref b, c, d, a, x[k + 0], S24, 0xe9b6c7aa); /* 20 */ GG(ref a, b, c, d, x[k + 5], S21, 0xd62f105d); /* 21 */ GG(ref d, a, b, c, x[k + 10], S22, 0x2441453); /* 22 */ GG(ref c, d, a, b, x[k + 15], S23, 0xd8a1e681); /* 23 */ GG(ref b, c, d, a, x[k + 4], S24, 0xe7d3fbc8); /* 24 */ GG(ref a, b, c, d, x[k + 9], S21, 0x21e1cde6); /* 25 */ GG(ref d, a, b, c, x[k + 14], S22, 0xc33707d6); /* 26 */ GG(ref c, d, a, b, x[k + 3], S23, 0xf4d50d87); /* 27 */ GG(ref b, c, d, a, x[k + 8], S24, 0x455a14ed); /* 28 */ GG(ref a, b, c, d, x[k + 13], S21, 0xa9e3e905); /* 29 */ GG(ref d, a, b, c, x[k + 2], S22, 0xfcefa3f8); /* 30 */ GG(ref c, d, a, b, x[k + 7], S23, 0x676f02d9); /* 31 */ GG(ref b, c, d, a, x[k + 12], S24, 0x8d2a4c8a); /* 32 */ /* Round 3 */ HH(ref a, b, c, d, x[k + 5], S31, 0xfffa3942); /* 33 */ HH(ref d, a, b, c, x[k + 8], S32, 0x8771f681); /* 34 */ HH(ref c, d, a, b, x[k + 11], S33, 0x6d9d6122); /* 35 */ HH(ref b, c, d, a, x[k + 14], S34, 0xfde5380c); /* 36 */ HH(ref a, b, c, d, x[k + 1], S31, 0xa4beea44); /* 37 */ HH(ref d, a, b, c, x[k + 4], S32, 0x4bdecfa9); /* 38 */ HH(ref c, d, a, b, x[k + 7], S33, 0xf6bb4b60); /* 39 */ HH(ref b, c, d, a, x[k + 10], S34, 0xbebfbc70); /* 40 */ HH(ref a, b, c, d, x[k + 13], S31, 0x289b7ec6); /* 41 */ HH(ref d, a, b, c, x[k + 0], S32, 0xeaa127fa); /* 42 */ HH(ref c, d, a, b, x[k + 3], S33, 0xd4ef3085); /* 43 */ HH(ref b, c, d, a, x[k + 6], S34, 0x4881d05); /* 44 */ HH(ref a, b, c, d, x[k + 9], S31, 0xd9d4d039); /* 45 */ HH(ref d, a, b, c, x[k + 12], S32, 0xe6db99e5); /* 46 */ HH(ref c, d, a, b, x[k + 15], S33, 0x1fa27cf8); /* 47 */ HH(ref b, c, d, a, x[k + 2], S34, 0xc4ac5665); /* 48 */ /* Round 4 */ II(ref a, b, c, d, x[k + 0], S41, 0xf4292244); /* 49 */ II(ref d, a, b, c, x[k + 7], S42, 0x432aff97); /* 50 */ II(ref c, d, a, b, x[k + 14], S43, 0xab9423a7); /* 51 */ II(ref b, c, d, a, x[k + 5], S44, 0xfc93a039); /* 52 */ II(ref a, b, c, d, x[k + 12], S41, 0x655b59c3); /* 53 */ II(ref d, a, b, c, x[k + 3], S42, 0x8f0ccc92); /* 54 */ II(ref c, d, a, b, x[k + 10], S43, 0xffeff47d); /* 55 */ II(ref b, c, d, a, x[k + 1], S44, 0x85845dd1); /* 56 */ II(ref a, b, c, d, x[k + 8], S41, 0x6fa87e4f); /* 57 */ II(ref d, a, b, c, x[k + 15], S42, 0xfe2ce6e0); /* 58 */ II(ref c, d, a, b, x[k + 6], S43, 0xa3014314); /* 59 */ II(ref b, c, d, a, x[k + 13], S44, 0x4e0811a1); /* 60 */ II(ref a, b, c, d, x[k + 4], S41, 0xf7537e82); /* 61 */ II(ref d, a, b, c, x[k + 11], S42, 0xbd3af235); /* 62 */ II(ref c, d, a, b, x[k + 2], S43, 0x2ad7d2bb); /* 63 */ II(ref b, c, d, a, x[k + 9], S44, 0xeb86d391); /* 64 */ A += a; B += b; C += c; D += d; } return new UInt32[] { A, B, C, D }; } public static byte[] MD5Array(byte[] input) { MD5_Init(); UInt32[] block = MD5_Append(input); UInt32[] bits = MD5_Trasform(block); /* Encodes bits (UInt32[]) into output (byte[]). Assumes len is * a multiple of 4. */ byte[] output = new byte[bits.Length * 4]; for (int i = 0, j = 0; i < bits.Length; i++, j += 4) { output[j] = (byte)(bits[i] & 0xff); output[j + 1] = (byte)((bits[i] >> 8) & 0xff); output[j + 2] = (byte)((bits[i] >> 16) & 0xff); output[j + 3] = (byte)((bits[i] >> 24) & 0xff); } return output; } public static string ArrayToHexString(byte[] array, bool uppercase) { string hexString = ""; string format = "x2"; if (uppercase) { format = "X2"; } foreach (byte b in array) { hexString += b.ToString(format); } return hexString; } public static string MDString(string message) { char[] c = message.ToCharArray(); byte[] b = new byte[c.Length]; for (int i = 0; i < c.Length; i++) { b[i] = (byte)c[i]; } byte[] digest = MD5Array(b); return ArrayToHexString(digest, false); } public static string MDFile(string fileName) { FileStream fs = File.Open(fileName, FileMode.Open, FileAccess.Read); byte[] array = new byte[fs.Length]; fs.Read(array, 0, (int)fs.Length); byte[] digest = MD5Array(array); fs.Close(); return ArrayToHexString(digest, false); } public static string Test(string message) { return MyMD5.MDString(message); } }
调用过程如下,
static void Main(string[] args) { string name = "yys"; string myresult = MyMD5.Test(name); string result = MD5Hash(name); Console.WriteLine(myresult); Console.WriteLine(result); Console.ReadLine(); } public static string MD5Hash(string value) { using (var md5 = MD5.Create()) { string ss = GetMd5Hash(md5, value); var result = md5.ComputeHash(Encoding.UTF8.GetBytes(value)); var strResult = BitConverter.ToString(result); return strResult.Replace("-", ""); } } public static string GetMd5Hash(MD5 md5Hash, string input) { byte[] data = md5Hash.ComputeHash(Encoding.UTF8.GetBytes(input)); StringBuilder sBuilder = new StringBuilder(); for (int i = 0; i < data.Length; i++) { sBuilder.Append(data[i].ToString("x2")); } return sBuilder.ToString(); }
结果如下,
为了比较,使用了C#默认的MD5方法和自己实现的MD5进行比较,其结果除大小写外是一致的。
代码下载: https://download.csdn.net/download/yysyangyangyangshan/10718208
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地理信息系统算法基础
张宏、温永宁、刘爱利/国别:中国大陆 / 科学出版社 / 2006-6 / 35.00元
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