Old: Sample code to generate the OneDrive Quick XOR Hash value for a file. The official documentation for the QuickXorHash is available here: https://learn.microsoft.com/en-us/onedrive/developer/code-snippets/quickxorhash?view=odsp-graph-online

QuickXorHash.cs

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namespace OneDrive
{
    using System;
    
    /// <summary>
    /// A quick, simple non-cryptographic hash algorithm that works by XORing the bytes in a circular-shifting fashion.
    ///
    /// A high level description of the algorithm without the introduction of the length is as follows:
    ///
    /// Let's say a "block" is a 160 bit block of bits (e.g. byte[20]).
    ///
    ///   method block zero():
    ///     returns a block with all zero bits.
    ///
    ///   method block extend8(byte b):
    ///     returns a block with all zero bits except for the lower 8 bits which come from b.
    ///
    ///   method block extend64(int64 i):
    ///     returns a block of all zero bits except for the lower 64 bits which come from i.
    ///
    ///   method block rotate(block bl, int n):
    ///     returns bl rotated left by n bits.
    ///
    ///   method block xor(block bl1, block bl2):
    ///     returns a bitwise xor of bl1 with bl2
    ///
    ///   method block XorHash0(byte rgb[], int cb):
    ///     block ret = zero()
    ///     for (int i = 0; i < cb; i ++)
    ///       ret = xor(ret, rotate(extend8(rgb[i]), i * 11))
    ///     returns ret
    ///
    ///   entrypoint block XorHash(byte rgb[], int cb):
    ///     returns xor(extend64(cb), XorHash0(rgb, cb))
    ///
    /// The final hash should xor the length of the data with the least significant bits of the resulting block.
    /// </summary>
    public class QuickXorHash : System.Security.Cryptography.HashAlgorithm
    {
        private const int BitsInLastCell = 32;
        private const byte Shift = 11;
        private const int Threshold = 600;
        private const byte WidthInBits = 160;

        private UInt64[] _data;
        private Int64 _lengthSoFar;
        private int _shiftSoFar;

        public QuickXorHash()
        {
            this.Initialize();
        }

        protected override void HashCore(byte[] array, int ibStart, int cbSize)
        {
            unchecked
            {
                int currentShift = this._shiftSoFar;

                // The bitvector where we'll start xoring
                int vectorArrayIndex = currentShift / 64;

                // The position within the bit vector at which we begin xoring
                int vectorOffset = currentShift % 64;
                int iterations = Math.Min(cbSize, QuickXorHash.WidthInBits);

                for (int i = 0; i < iterations; i++)
                {
                    bool isLastCell = vectorArrayIndex == this._data.Length - 1;
                    int bitsInVectorCell = isLastCell ? QuickXorHash.BitsInLastCell : 64;

                    // There's at least 2 bitvectors before we reach the end of the array
                    if (vectorOffset <= bitsInVectorCell - 8)
                    {
                        for (int j = ibStart + i; j < cbSize + ibStart; j += QuickXorHash.WidthInBits)
                        {
                            this._data[vectorArrayIndex] ^= (ulong)array[j] << vectorOffset;
                        }
                    }
                    else
                    {
                        int index1 = vectorArrayIndex;
                        int index2 = isLastCell ? 0 : (vectorArrayIndex + 1);
                        byte low = (byte)(bitsInVectorCell - vectorOffset);

                        byte xoredByte = 0;
                        for (int j = ibStart + i; j < cbSize + ibStart; j += QuickXorHash.WidthInBits)
                        {
                            xoredByte ^= array[j];
                        }
                        this._data[index1] ^= (ulong)xoredByte << vectorOffset;
                        this._data[index2] ^= (ulong)xoredByte >> low;
                    }
                    vectorOffset += QuickXorHash.Shift;
                    while (vectorOffset >= bitsInVectorCell)
                    {
                        vectorArrayIndex = isLastCell ? 0 : vectorArrayIndex + 1;
                        vectorOffset -= bitsInVectorCell;
                    }
                }

                // Update the starting position in a circular shift pattern
                this._shiftSoFar = (this._shiftSoFar + QuickXorHash.Shift * (cbSize % QuickXorHash.WidthInBits)) % QuickXorHash.WidthInBits;
            }

            this._lengthSoFar += cbSize;
        }

        protected override byte[] HashFinal()
        {
            // Create a byte array big enough to hold all our data
            byte[] rgb = new byte[(QuickXorHash.WidthInBits - 1) / 8 + 1];

            // Block copy all our bitvectors to this byte array
            for (Int32 i = 0; i < this._data.Length - 1; i++)
            {
                Buffer.BlockCopy(
                    BitConverter.GetBytes(this._data[i]), 0,
                    rgb, i * 8,
                    8);
            }

            Buffer.BlockCopy(
                BitConverter.GetBytes(this._data[this._data.Length - 1]), 0,
                rgb, (this._data.Length - 1) * 8,
                rgb.Length - (this._data.Length - 1) * 8);

            // XOR the file length with the least significant bits
            // Note that GetBytes is architecture-dependent, so care should
            // be taken with porting. The expected value is 8-bytes in length in little-endian format
            var lengthBytes = BitConverter.GetBytes(this._lengthSoFar);
            System.Diagnostics.Debug.Assert(lengthBytes.Length == 8);
            for (int i = 0; i < lengthBytes.Length; i++)
            {
                rgb[(QuickXorHash.WidthInBits / 8) - lengthBytes.Length + i] ^= lengthBytes[i];
            }

            return rgb;
        }

        public override sealed void Initialize()
        {
            this._data = new ulong[(QuickXorHash.WidthInBits - 1) / 64 + 1];
            this._shiftSoFar = 0;
            this._lengthSoFar = 0;
        }

        public override int HashSize
        {
            get
            {
                return QuickXorHash.WidthInBits;
            }
        }
    }
}

Can you qualify the names byte[] array, int ibStart, int cbSize, byte rgb[], int cb that you use in your pseudocode and in the implementation? What do they stand for?

Nevermind, found .net docs at https://msdn.microsoft.com/en-us/library/system.security.cryptography.hashalgorithm.hashcore(v=vs.110).aspx

I added this code to a hash tool I created, but when I compare the QuickXorHash value for a file that exists on my local machine as well as my OneDrive for Business, the values are different. I was hoping to use this as a quick way to verify the files are still identical between local drives and OneDrive (since this is the only hash value available for OneDrive for Business accounts). Any ideas on why the values for the exact same file would be different?

QuickXorHash code sample result:

OneDrive Graph API result:

I found the issue, and it was in the way I was converting the byte array to a string.
Here is the code I was using originally:

int i;
StringBuilder outPut = new StringBuilder(byteArray.Length);
for (i = 0; i < byteArray.Length; i++)
{
     outPut.Append(byteArray[i].ToString("x2"));
}
return outPut.ToString();

But, after some more research, here is what I found that worked correctly, and is also cleaner:
return Convert.ToBase64String(byteArray);

This results in the hash now matching what OneDrive returns.

It took me a few hours to figure out that Sharepoint give you a unexpected XOR if you upload the file with .msg extension....

@buzzluck68
byte[] byteArray = { 48, 49, 86, 50, 75, 85, 89, 82, 70, 81 ,72, 53, 72 ,69, 86, 52, 82, 85, 84 ,82, 66, 73, 87, 87 ,79 ,76 ,84, 73, 50 ,83, 78, 83, 81, 80 };
int i;
StringBuilder outPut = new StringBuilder(byteArray.Length);
for (i = 0; i < byteArray.Length; i++)
{
outPut.Append(byteArray[i].ToString("x2"));
}
var base64encoded = Convert.ToBase64String(byteArray);
Console.WriteLine(base64encoded); but for me result is not matching what OneDrive returns.

but for me result is not matching what OneDrive returns.

@vikram9491 what kind if file are you uploading? OneDrive rewrite some uploaded files and therefor the xor is also changed (apparently)

@moander Actually I need to find deduplication files i am using .docx file , for that i need to create quickxorhash , but when i try ike above is not matching what OneDrive api returns.

@moander I tried like this to still i am not able to create quickxorhash value
byte[] hashArray = { 48, 49, 86, 50, 75, 85, 89, 82, 70, 81 ,72, 53, 72 ,69, 86, 52, 82, 85, 84 ,82, 66, 73, 87, 87 ,79 ,76 ,84, 73, 50 ,83, 78, 83, 81, 80 };
quickXorHash.HashCore(hashArray,0,hashArray.Length);
var hashValue = quickXorHash.HashFinal();

    Console.WriteLine("OneDrive QuickXorHash Value:");
    foreach (var b in hashValue)
    {
        Console.Write(b + " ");
	}
   // Convert the hash value to Base64 string
    string base64Hash = Convert.ToBase64String(hashValue);
    Console.WriteLine("\nBase64 Hash Value: " + base64Hash);

In addition to that suppose if my bitsinlastcell input has 272 bit and output has widthinbits has 242 bit then what is shift and threshold value i should give ......?
in this line what hashlength i should pass...? quickXorHash.HashCore(hashArray,0,hashArray.Length);

@vikram9491 let me know if you figure it out. I concluded that it is not possible. The calculated xor is correct but the .docx or .eml file is modified so it's impossible for you to calculate the correct xor beforehand 👎