295 lines
12 KiB
C#
295 lines
12 KiB
C#
//Copyright (c) Microsoft Corporation. All rights reserved.
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using System;
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using System.Text;
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namespace SharpCifs.Util.Sharpen
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{
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// **************************************************************
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// * Raw implementation of the MD5 hash algorithm
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// * from RFC 1321.
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// *
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// * Written By: Reid Borsuk and Jenny Zheng
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// * Copyright (c) Microsoft Corporation. All rights reserved.
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// **************************************************************
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// Simple struct for the (a,b,c,d) which is used to compute the mesage digest.
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struct AbcdStruct
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{
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public uint A;
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public uint B;
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public uint C;
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public uint D;
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}
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public sealed class Md5Core
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{
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//Prevent CSC from adding a default public constructor
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private Md5Core() { }
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public static byte[] GetHash(string input, Encoding encoding)
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{
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if (null == input)
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throw new ArgumentNullException(
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"input", "Unable to calculate hash over null input data");
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if (null == encoding)
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throw new ArgumentNullException(
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"encoding",
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"Unable to calculate hash over a string without a default encoding. "
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+ "Consider using the GetHash(string) overload to use UTF8 Encoding");
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byte[] target = encoding.GetBytes(input);
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return GetHash(target);
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}
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public static byte[] GetHash(string input)
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{
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return GetHash(input, new UTF8Encoding());
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}
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public static string GetHashString(byte[] input)
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{
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if (null == input)
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throw new ArgumentNullException(
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"input", "Unable to calculate hash over null input data");
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string retval = BitConverter.ToString(GetHash(input));
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retval = retval.Replace("-", "");
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return retval;
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}
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public static string GetHashString(string input, Encoding encoding)
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{
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if (null == input)
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throw new ArgumentNullException(
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"input", "Unable to calculate hash over null input data");
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if (null == encoding)
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throw new ArgumentNullException(
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"encoding",
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"Unable to calculate hash over a string without a default encoding. "
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+ "Consider using the GetHashString(string) overload to use UTF8 Encoding");
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byte[] target = encoding.GetBytes(input);
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return GetHashString(target);
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}
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public static string GetHashString(string input)
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{
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return GetHashString(input, new UTF8Encoding());
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}
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public static byte[] GetHash(byte[] input)
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{
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if (null == input)
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throw new ArgumentNullException(
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"input", "Unable to calculate hash over null input data");
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//Intitial values defined in RFC 1321
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AbcdStruct abcd = new AbcdStruct();
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abcd.A = 0x67452301;
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abcd.B = 0xefcdab89;
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abcd.C = 0x98badcfe;
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abcd.D = 0x10325476;
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//We pass in the input array by block, the final block of data must be handled specialy for padding & length embeding
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int startIndex = 0;
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while (startIndex <= input.Length - 64)
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{
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GetHashBlock(input, ref abcd, startIndex);
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startIndex += 64;
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}
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// The final data block.
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return GetHashFinalBlock(input,
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startIndex,
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input.Length - startIndex,
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abcd,
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(Int64)input.Length * 8);
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}
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internal static byte[] GetHashFinalBlock(byte[] input,
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int ibStart,
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int cbSize,
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AbcdStruct abcd,
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Int64 len)
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{
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byte[] working = new byte[64];
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byte[] length = BitConverter.GetBytes(len);
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//Padding is a single bit 1, followed by the number of 0s required to make size congruent to 448 modulo 512. Step 1 of RFC 1321
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//The CLR ensures that our buffer is 0-assigned, we don't need to explicitly set it. This is why it ends up being quicker to just
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//use a temporary array rather then doing in-place assignment (5% for small inputs)
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Array.Copy(input, ibStart, working, 0, cbSize);
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working[cbSize] = 0x80;
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//We have enough room to store the length in this chunk
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if (cbSize < 56)
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{
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Array.Copy(length, 0, working, 56, 8);
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GetHashBlock(working, ref abcd, 0);
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}
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else //We need an aditional chunk to store the length
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{
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GetHashBlock(working, ref abcd, 0);
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//Create an entirely new chunk due to the 0-assigned trick mentioned above, to avoid an extra function call clearing the array
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working = new byte[64];
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Array.Copy(length, 0, working, 56, 8);
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GetHashBlock(working, ref abcd, 0);
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}
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byte[] output = new byte[16];
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Array.Copy(BitConverter.GetBytes(abcd.A), 0, output, 0, 4);
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Array.Copy(BitConverter.GetBytes(abcd.B), 0, output, 4, 4);
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Array.Copy(BitConverter.GetBytes(abcd.C), 0, output, 8, 4);
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Array.Copy(BitConverter.GetBytes(abcd.D), 0, output, 12, 4);
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return output;
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}
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// Performs a single block transform of MD5 for a given set of ABCD inputs
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/* If implementing your own hashing framework, be sure to set the initial ABCD correctly according to RFC 1321:
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// A = 0x67452301;
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// B = 0xefcdab89;
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// C = 0x98badcfe;
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// D = 0x10325476;
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*/
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internal static void GetHashBlock(byte[] input, ref AbcdStruct abcdValue, int ibStart)
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{
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uint[] temp = Converter(input, ibStart);
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uint a = abcdValue.A;
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uint b = abcdValue.B;
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uint c = abcdValue.C;
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uint d = abcdValue.D;
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a = R1(a, b, c, d, temp[0], 7, 0xd76aa478);
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d = R1(d, a, b, c, temp[1], 12, 0xe8c7b756);
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c = R1(c, d, a, b, temp[2], 17, 0x242070db);
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b = R1(b, c, d, a, temp[3], 22, 0xc1bdceee);
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a = R1(a, b, c, d, temp[4], 7, 0xf57c0faf);
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d = R1(d, a, b, c, temp[5], 12, 0x4787c62a);
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c = R1(c, d, a, b, temp[6], 17, 0xa8304613);
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b = R1(b, c, d, a, temp[7], 22, 0xfd469501);
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a = R1(a, b, c, d, temp[8], 7, 0x698098d8);
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d = R1(d, a, b, c, temp[9], 12, 0x8b44f7af);
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c = R1(c, d, a, b, temp[10], 17, 0xffff5bb1);
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b = R1(b, c, d, a, temp[11], 22, 0x895cd7be);
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a = R1(a, b, c, d, temp[12], 7, 0x6b901122);
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d = R1(d, a, b, c, temp[13], 12, 0xfd987193);
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c = R1(c, d, a, b, temp[14], 17, 0xa679438e);
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b = R1(b, c, d, a, temp[15], 22, 0x49b40821);
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a = R2(a, b, c, d, temp[1], 5, 0xf61e2562);
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d = R2(d, a, b, c, temp[6], 9, 0xc040b340);
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c = R2(c, d, a, b, temp[11], 14, 0x265e5a51);
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b = R2(b, c, d, a, temp[0], 20, 0xe9b6c7aa);
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a = R2(a, b, c, d, temp[5], 5, 0xd62f105d);
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d = R2(d, a, b, c, temp[10], 9, 0x02441453);
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c = R2(c, d, a, b, temp[15], 14, 0xd8a1e681);
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b = R2(b, c, d, a, temp[4], 20, 0xe7d3fbc8);
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a = R2(a, b, c, d, temp[9], 5, 0x21e1cde6);
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d = R2(d, a, b, c, temp[14], 9, 0xc33707d6);
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c = R2(c, d, a, b, temp[3], 14, 0xf4d50d87);
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b = R2(b, c, d, a, temp[8], 20, 0x455a14ed);
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a = R2(a, b, c, d, temp[13], 5, 0xa9e3e905);
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d = R2(d, a, b, c, temp[2], 9, 0xfcefa3f8);
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c = R2(c, d, a, b, temp[7], 14, 0x676f02d9);
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b = R2(b, c, d, a, temp[12], 20, 0x8d2a4c8a);
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a = R3(a, b, c, d, temp[5], 4, 0xfffa3942);
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d = R3(d, a, b, c, temp[8], 11, 0x8771f681);
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c = R3(c, d, a, b, temp[11], 16, 0x6d9d6122);
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b = R3(b, c, d, a, temp[14], 23, 0xfde5380c);
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a = R3(a, b, c, d, temp[1], 4, 0xa4beea44);
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d = R3(d, a, b, c, temp[4], 11, 0x4bdecfa9);
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c = R3(c, d, a, b, temp[7], 16, 0xf6bb4b60);
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b = R3(b, c, d, a, temp[10], 23, 0xbebfbc70);
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a = R3(a, b, c, d, temp[13], 4, 0x289b7ec6);
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d = R3(d, a, b, c, temp[0], 11, 0xeaa127fa);
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c = R3(c, d, a, b, temp[3], 16, 0xd4ef3085);
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b = R3(b, c, d, a, temp[6], 23, 0x04881d05);
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a = R3(a, b, c, d, temp[9], 4, 0xd9d4d039);
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d = R3(d, a, b, c, temp[12], 11, 0xe6db99e5);
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c = R3(c, d, a, b, temp[15], 16, 0x1fa27cf8);
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b = R3(b, c, d, a, temp[2], 23, 0xc4ac5665);
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a = R4(a, b, c, d, temp[0], 6, 0xf4292244);
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d = R4(d, a, b, c, temp[7], 10, 0x432aff97);
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c = R4(c, d, a, b, temp[14], 15, 0xab9423a7);
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b = R4(b, c, d, a, temp[5], 21, 0xfc93a039);
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a = R4(a, b, c, d, temp[12], 6, 0x655b59c3);
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d = R4(d, a, b, c, temp[3], 10, 0x8f0ccc92);
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c = R4(c, d, a, b, temp[10], 15, 0xffeff47d);
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b = R4(b, c, d, a, temp[1], 21, 0x85845dd1);
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a = R4(a, b, c, d, temp[8], 6, 0x6fa87e4f);
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d = R4(d, a, b, c, temp[15], 10, 0xfe2ce6e0);
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c = R4(c, d, a, b, temp[6], 15, 0xa3014314);
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b = R4(b, c, d, a, temp[13], 21, 0x4e0811a1);
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a = R4(a, b, c, d, temp[4], 6, 0xf7537e82);
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d = R4(d, a, b, c, temp[11], 10, 0xbd3af235);
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c = R4(c, d, a, b, temp[2], 15, 0x2ad7d2bb);
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b = R4(b, c, d, a, temp[9], 21, 0xeb86d391);
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abcdValue.A = unchecked(a + abcdValue.A);
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abcdValue.B = unchecked(b + abcdValue.B);
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abcdValue.C = unchecked(c + abcdValue.C);
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abcdValue.D = unchecked(d + abcdValue.D);
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}
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//Manually unrolling these equations nets us a 20% performance improvement
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private static uint R1(uint a, uint b, uint c, uint d, uint x, int s, uint t)
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{
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// (b + LSR((a + F(b, c, d) + x + t), s))
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//F(x, y, z) ((x & y) | ((x ^ 0xFFFFFFFF) & z))
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return unchecked(b + Lsr((a + ((b & c) | ((b ^ 0xFFFFFFFF) & d)) + x + t), s));
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}
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private static uint R2(uint a, uint b, uint c, uint d, uint x, int s, uint t)
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{
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// (b + LSR((a + G(b, c, d) + x + t), s))
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//G(x, y, z) ((x & z) | (y & (z ^ 0xFFFFFFFF)))
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return unchecked(b + Lsr((a + ((b & d) | (c & (d ^ 0xFFFFFFFF))) + x + t), s));
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}
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private static uint R3(uint a, uint b, uint c, uint d, uint x, int s, uint t)
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{
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// (b + LSR((a + H(b, c, d) + k + i), s))
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//H(x, y, z) (x ^ y ^ z)
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return unchecked(b + Lsr((a + (b ^ c ^ d) + x + t), s));
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}
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private static uint R4(uint a, uint b, uint c, uint d, uint x, int s, uint t)
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{
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// (b + LSR((a + I(b, c, d) + k + i), s))
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//I(x, y, z) (y ^ (x | (z ^ 0xFFFFFFFF)))
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return unchecked(b + Lsr((a + (c ^ (b | (d ^ 0xFFFFFFFF))) + x + t), s));
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}
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// Implementation of left rotate
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// s is an int instead of a uint becuase the CLR requires the argument passed to >>/<< is of
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// type int. Doing the demoting inside this function would add overhead.
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private static uint Lsr(uint i, int s)
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{
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return ((i << s) | (i >> (32 - s)));
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}
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//Convert input array into array of UInts
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private static uint[] Converter(byte[] input, int ibStart)
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{
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if (null == input)
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throw new ArgumentNullException(
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"input", "Unable convert null array to array of uInts");
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uint[] result = new uint[16];
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for (int i = 0; i < 16; i++)
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{
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result[i] = input[ibStart + i * 4];
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result[i] += (uint)input[ibStart + i * 4 + 1] << 8;
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result[i] += (uint)input[ibStart + i * 4 + 2] << 16;
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result[i] += (uint)input[ibStart + i * 4 + 3] << 24;
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}
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return result;
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}
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}
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} |