.net - C#中大文件的容错MD5计算

Question

有没有办法对大文件进行增量 md5 计算，但在每个第 n 步保存读取位置和 md5 状态数据，例如当进程失败或网络/IO 发生时，然后它可以从最后一个已知的好位置重新启动文件。

Answer 1

这是我对问题的解决方案和单元测试，以显示概念证明。

using System;
using System.IO;
using System.Text;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using SInnovations.Azure.Storage.MD5;
namespace Tests
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {

            var md5 = new MD5Managed();
            MD5Managed md5state = null;

            var bytes = new byte[1024 * 8];
            using (var stream = File.OpenRead(@"C:\test\c2474dab-f209-4a7c-8ed4-b7ba71c5b799.zip"))
            {
                var i = new Random().Next(0, (int)stream.Length / bytes.Length);
                while (stream.Read(bytes, 0, bytes.Length) != 0)
                {
                    md5.TransformBlock(bytes, 0, bytes.Length, null, 0);

                    if (!(i-- > 0))
                    {
                        if (md5state == null)
                        {
                            md5state = new MD5Managed();
                            var state = md5.GetState();
                            md5state.LoadState(state);
                        }
                        else
                        {
                            md5state.TransformBlock(bytes, 0, bytes.Length, null, 0);
                        }

                    }

                }
            }

            md5.TransformFinalBlock(bytes, 0, 0);
            md5state.TransformFinalBlock(bytes, 0, 0);

            string md5Hash = GetMDHASH(md5);
            string md5HashStated = GetMDHASH(md5state);

            Assert.AreEqual(md5Hash, md5HashStated);
            Console.WriteLine(md5Hash);

        }

        private static string GetMDHASH(MD5Managed md5)
        {
            System.Text.StringBuilder s = new System.Text.StringBuilder();
            foreach (byte b in md5.Hash)
            {
                s.Append(b.ToString("x2").ToLower());
            }
            var md5Hash = s.ToString();
            return md5Hash;
        }
    }
}

和 md5 哈希算法

namespace SInnovations.Azure.Storage.MD5
{
    using System;
    using System.Diagnostics.CodeAnalysis;
    using System.Security.Cryptography;
    using System.Linq;

    /// <summary>
    /// MD5Managed: A HashAlgorithm implementation that acts as a thin wrapper
    /// around a C# translation of the MD5 reference implementation. The C code
    /// has been translated as closely as possible so that most of the original
    /// structure remains and comparisons between the two are straightforward.
    /// </summary>
    /// <remarks>
    /// Derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm.
    /// 
    /// Specification:
    /// RFC1321 - The MD5 Message-Digest Algorithm
    /// http://www.faqs.org/rfcs/rfc1321.html
    /// 
    /// Original license:
    /// Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
    /// rights reserved.
    /// 
    /// License to copy and use this software is granted provided that it
    /// is identified as the "RSA Data Security, Inc. MD5 Message-Digest
    /// Algorithm" in all material mentioning or referencing this software
    /// or this function.
    /// 
    /// License is also granted to make and use derivative works provided
    /// that such works are identified as "derived from the RSA Data
    /// Security, Inc. MD5 Message-Digest Algorithm" in all material
    /// mentioning or referencing the derived work.
    /// 
    /// RSA Data Security, Inc. makes no representations concerning either
    /// the merchantability of this software or the suitability of this
    /// software for any particular purpose. It is provided "as is"
    /// without express or implied warranty of any kind.
    /// 
    /// These notices must be retained in any copies of any part of this
    /// documentation and/or software.
    /// </remarks>
    public class MD5Managed : HashAlgorithm
    {
        // Current context
        private readonly MD5_CTX _context = new MD5_CTX();
        // Last hash result
        private readonly byte[] _digest = new byte[16];
        // True if HashCore has been called
        private bool _hashCoreCalled;
        // True if HashFinal has been called
        private bool _hashFinalCalled;

        /// <summary>
        /// Initializes a new instance.
        /// </summary>
        public MD5Managed()
        {
            InitializeVariables();
        }

        /// <summary>
        /// Initializes internal state.
        /// </summary>
        public override void Initialize()
        {
            InitializeVariables();
        }

        /// <summary>
        /// Initializes variables.
        /// </summary>
        private void InitializeVariables()
        {
            MD5Init(_context);
            _hashCoreCalled = false;
            _hashFinalCalled = false;
        }

        /// <summary>
        /// Updates the hash code with the data provided.
        /// </summary>
        /// <param name="array">Data to hash.</param>
        /// <param name="ibStart">Start position.</param>
        /// <param name="cbSize">Number of bytes.</param>
        protected override void HashCore(byte[] array, int ibStart, int cbSize)
        {
            if (null == array)
            {
                throw new ArgumentNullException("array");
            }

            if (_hashFinalCalled)
            {
                throw new CryptographicException("Hash not valid for use in specified state.");
            }
            _hashCoreCalled = true;

            MD5Update(_context, array, (uint)ibStart, (uint)cbSize);
        }

        /// <summary>
        /// Finalizes the hash code and returns it.
        /// </summary>
        /// <returns></returns>
        protected override byte[] HashFinal()
        {
            _hashFinalCalled = true;
            MD5Final(_digest, _context);
            return Hash;
        }

        /// <summary>
        /// Returns the hash as an array of bytes.
        /// </summary>
        [SuppressMessage("Microsoft.Design", "CA1065:DoNotRaiseExceptionsInUnexpectedLocations", Justification = "Matching .NET behavior by throwing here.")]
        [SuppressMessage("Microsoft.Usage", "CA2201:DoNotRaiseReservedExceptionTypes", Justification = "Matching .NET behavior by throwing NullReferenceException.")]
        public override byte[] Hash
        {
            get
            {
                if (!_hashCoreCalled)
                {
                    throw new NullReferenceException();
                }
                if (!_hashFinalCalled)
                {
                    // Note: Not CryptographicUnexpectedOperationException because that can't be instantiated on Silverlight 4
                    throw new CryptographicException("Hash must be finalized before the hash value is retrieved.");
                }

                return _digest;
            }
        }

        // Return size of hash in bits.
        public override int HashSize
        {
            get
            {
                return _digest.Length * 8;
            }
        }

        ///////////////////////////////////////////////
        // MD5 reference implementation begins here. //
        ///////////////////////////////////////////////

        /* MD5 context. */
        private class MD5_CTX
        {
            public readonly uint[] state;   /* state (ABCD) */
            public readonly uint[] count;   /* number of bits, modulo 2^64 (lsb first) */
            public readonly byte[] buffer;  /* input buffer */

            public MD5_CTX()
            {
                state = new uint[4];
                count = new uint[2];
                buffer = new byte[64];
            }

            public void Clear()
            {
                Array.Clear(state, 0, state.Length);
                Array.Clear(count, 0, count.Length);
                Array.Clear(buffer, 0, buffer.Length);
            }
        }

        /* Constants for MD5Transform routine. */
        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;

        private static byte[] PADDING;

        [SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline", Justification = "More compact this way")]
        static MD5Managed()
        {
            PADDING = new byte[64];
            PADDING[0] = 0x80;
        }

        /* F, G, H and I are basic MD5 functions. */
        private static uint F(uint x, uint y, uint z) { return (((x) & (y)) | ((~x) & (z))); }
        private static uint G(uint x, uint y, uint z) { return (((x) & (z)) | ((y) & (~z))); }
        private static uint H(uint x, uint y, uint z) { return ((x) ^ (y) ^ (z)); }
        private static uint I(uint x, uint y, uint z) { return ((y) ^ ((x) | (~z))); }

        /* ROTATE_LEFT rotates x left n bits. */
        private static uint ROTATE_LEFT(uint x, int n) { return (((x) << (n)) | ((x) >> (32 - (n)))); }

        /* 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 uint a, uint b, uint c, uint d, uint x, int s, uint ac)
        {
            (a) += F((b), (c), (d)) + (x) + (uint)(ac);
            (a) = ROTATE_LEFT((a), (s));
            (a) += (b);
        }
        private static void GG(ref uint a, uint b, uint c, uint d, uint x, int s, uint ac)
        {
            (a) += G((b), (c), (d)) + (x) + (uint)(ac);
            (a) = ROTATE_LEFT((a), (s));
            (a) += (b);
        }
        private static void HH(ref uint a, uint b, uint c, uint d, uint x, int s, uint ac)
        {
            (a) += H((b), (c), (d)) + (x) + (uint)(ac);
            (a) = ROTATE_LEFT((a), (s));
            (a) += (b);
        }
        private static void II(ref uint a, uint b, uint c, uint d, uint x, int s, uint ac)
        {
            (a) += I((b), (c), (d)) + (x) + (uint)(ac);
            (a) = ROTATE_LEFT((a), (s));
            (a) += (b);
        }

        /* MD5 initialization. Begins an MD5 operation, writing a new context. */
        private static void MD5Init(MD5_CTX context)  /* context */
        {
            context.count[0] = context.count[1] = 0;

            /* Load magic initialization constants. */
            context.state[0] = 0x67452301;
            context.state[1] = 0xefcdab89;
            context.state[2] = 0x98badcfe;
            context.state[3] = 0x10325476;
        }

        /* MD5 block update operation. Continues an MD5 message-digest
           operation, processing another message block, and updating the
           context. */
        private static void MD5Update(MD5_CTX context,  /* context */
                                      byte[] input,     /* input block */
                                      uint inputIndex,  // Starting index for input block
                                      uint inputLen)    /* length of input block */
        {
            /* Compute number of bytes mod 64 */
            uint index = (uint)((context.count[0] >> 3) & 0x3F);

            /* Update number of bits */
            if ((context.count[0] += ((uint)inputLen << 3)) < ((uint)inputLen << 3))
            {
                context.count[1]++;
            }
            context.count[1] += ((uint)inputLen >> 29);

            uint partLen = 64 - index;

            /* Transform as many times as possible. */
            uint i = 0;
            if (inputLen >= partLen)
            {
                Buffer.BlockCopy(input, (int)inputIndex, context.buffer, (int)index, (int)partLen);
                MD5Transform(context.state, context.buffer, 0);

                for (i = partLen; i + 63 < inputLen; i += 64)
                {
                    MD5Transform(context.state, input, inputIndex + i);
                }

                index = 0;
            }

            /* Buffer remaining input */
            Buffer.BlockCopy(input, (int)(inputIndex + i), context.buffer, (int)index, (int)(inputLen - i));
        }

        /* MD5 finalization. Ends an MD5 message-digest operation, writing the
           the message digest and zeroizing the context. */
        private static void MD5Final(byte[] digest,    /* message digest */
                                     MD5_CTX context)  /* context */
        {
            byte[] bits = new byte[8];

            /* Save number of bits */
            Encode(bits, context.count, 8);

            /* Pad out to 56 mod 64. */
            uint index = (uint)((context.count[0] >> 3) & 0x3f);
            uint padLen = (index < 56) ? (56 - index) : (120 - index);
            MD5Update(context, PADDING, 0, padLen);

            /* Append length (before padding) */
            MD5Update(context, bits, 0, 8);

            /* Store state in digest */
            Encode(digest, context.state, 16);

            /* Zeroize sensitive information. */
            context.Clear();
        }

        /* MD5 basic transformation. Transforms state based on block. */
        private static void MD5Transform(uint[] state,
                                         byte[] block,
                                         uint blockIndex)
        {
            uint a = state[0], b = state[1], c = state[2], d = state[3];
            uint[] x = new uint[16];

            Decode(x, block, blockIndex, 64);

            /* Round 1 */
            FF(ref a, b, c, d, x[0], S11, 0xd76aa478); /* 1 */
            FF(ref d, a, b, c, x[1], S12, 0xe8c7b756); /* 2 */
            FF(ref c, d, a, b, x[2], S13, 0x242070db); /* 3 */
            FF(ref b, c, d, a, x[3], S14, 0xc1bdceee); /* 4 */
            FF(ref a, b, c, d, x[4], S11, 0xf57c0faf); /* 5 */
            FF(ref d, a, b, c, x[5], S12, 0x4787c62a); /* 6 */
            FF(ref c, d, a, b, x[6], S13, 0xa8304613); /* 7 */
            FF(ref b, c, d, a, x[7], S14, 0xfd469501); /* 8 */
            FF(ref a, b, c, d, x[8], S11, 0x698098d8); /* 9 */
            FF(ref d, a, b, c, x[9], S12, 0x8b44f7af); /* 10 */
            FF(ref c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
            FF(ref b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
            FF(ref a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
            FF(ref d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
            FF(ref c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
            FF(ref b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

            /* Round 2 */
            GG(ref a, b, c, d, x[1], S21, 0xf61e2562); /* 17 */
            GG(ref d, a, b, c, x[6], S22, 0xc040b340); /* 18 */
            GG(ref c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
            GG(ref b, c, d, a, x[0], S24, 0xe9b6c7aa); /* 20 */
            GG(ref a, b, c, d, x[5], S21, 0xd62f105d); /* 21 */
            GG(ref d, a, b, c, x[10], S22, 0x02441453); /* 22 */
            GG(ref c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
            GG(ref b, c, d, a, x[4], S24, 0xe7d3fbc8); /* 24 */
            GG(ref a, b, c, d, x[9], S21, 0x21e1cde6); /* 25 */
            GG(ref d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
            GG(ref c, d, a, b, x[3], S23, 0xf4d50d87); /* 27 */
            GG(ref b, c, d, a, x[8], S24, 0x455a14ed); /* 28 */
            GG(ref a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
            GG(ref d, a, b, c, x[2], S22, 0xfcefa3f8); /* 30 */
            GG(ref c, d, a, b, x[7], S23, 0x676f02d9); /* 31 */
            GG(ref b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

            /* Round 3 */
            HH(ref a, b, c, d, x[5], S31, 0xfffa3942); /* 33 */
            HH(ref d, a, b, c, x[8], S32, 0x8771f681); /* 34 */
            HH(ref c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
            HH(ref b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
            HH(ref a, b, c, d, x[1], S31, 0xa4beea44); /* 37 */
            HH(ref d, a, b, c, x[4], S32, 0x4bdecfa9); /* 38 */
            HH(ref c, d, a, b, x[7], S33, 0xf6bb4b60); /* 39 */
            HH(ref b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
            HH(ref a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
            HH(ref d, a, b, c, x[0], S32, 0xeaa127fa); /* 42 */
            HH(ref c, d, a, b, x[3], S33, 0xd4ef3085); /* 43 */
            HH(ref b, c, d, a, x[6], S34, 0x04881d05); /* 44 */
            HH(ref a, b, c, d, x[9], S31, 0xd9d4d039); /* 45 */
            HH(ref d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
            HH(ref c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
            HH(ref b, c, d, a, x[2], S34, 0xc4ac5665); /* 48 */

            /* Round 4 */
            II(ref a, b, c, d, x[0], S41, 0xf4292244); /* 49 */
            II(ref d, a, b, c, x[7], S42, 0x432aff97); /* 50 */
            II(ref c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
            II(ref b, c, d, a, x[5], S44, 0xfc93a039); /* 52 */
            II(ref a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
            II(ref d, a, b, c, x[3], S42, 0x8f0ccc92); /* 54 */
            II(ref c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
            II(ref b, c, d, a, x[1], S44, 0x85845dd1); /* 56 */
            II(ref a, b, c, d, x[8], S41, 0x6fa87e4f); /* 57 */
            II(ref d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
            II(ref c, d, a, b, x[6], S43, 0xa3014314); /* 59 */
            II(ref b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
            II(ref a, b, c, d, x[4], S41, 0xf7537e82); /* 61 */
            II(ref d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
            II(ref c, d, a, b, x[2], S43, 0x2ad7d2bb); /* 63 */
            II(ref b, c, d, a, x[9], S44, 0xeb86d391); /* 64 */

            state[0] += a;
            state[1] += b;
            state[2] += c;
            state[3] += d;

            /* Zeroize sensitive information. */
            Array.Clear(x, 0, x.Length);
        }

        /* Encodes input (UINT4) into output (unsigned char). Assumes len is
           a multiple of 4. */
        private static void Encode(byte[] output,
                                   uint[] input,
                                   uint len)
        {
            for (uint i = 0, j = 0; j < len; i++, j += 4)
            {
                output[j] = (byte)(input[i] & 0xff);
                output[j + 1] = (byte)((input[i] >> 8) & 0xff);
                output[j + 2] = (byte)((input[i] >> 16) & 0xff);
                output[j + 3] = (byte)((input[i] >> 24) & 0xff);
            }
        }

        /* Decodes input (unsigned char) into output (UINT4). Assumes len is
           a multiple of 4. */
        private static void Decode(uint[] output,
                                   byte[] input,
                                   uint inputIndex,
                                   uint len)
        {
            for (uint i = 0, j = 0; j < len; i++, j += 4)
            {
                output[i] = ((uint)input[inputIndex + j]) |
                    (((uint)input[inputIndex + j + 1]) << 8) |
                    (((uint)input[inputIndex + j + 2]) << 16) |
                    (((uint)input[inputIndex + j + 3]) << 24);
            }
        }

        public object GetState()
        {
            return new StateSerialize
            {
                state = _context.state.Clone() as uint[],
                count = _context.count.Clone() as uint[],
                buffer = _context.buffer.Clone() as byte[]
            };
        }

        public void LoadState(object state)
        {
            var s = state as StateSerialize;
            Array.Copy(s.buffer, _context.buffer, _context.buffer.Length);
            Array.Copy(s.count, _context.count, _context.count.Length);
            Array.Copy(s.state, _context.state, _context.state.Length);
        }

        [Serializable]
        class StateSerialize
        {
            public uint[] state { get; set; }
            public uint[] count { get; set; }
            public byte[] buffer { get; set; }
        }
    }

}