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HashAlgorithm.ComputeHash Method (Stream)

Computes the hash value for the specified Stream object.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

public byte[] ComputeHash(
	Stream inputStream
)

Parameters

inputStream
Type: System.IO.Stream
The input to compute the hash code for.

Return Value

Type: System.Byte[]
The computed hash code.

ExceptionCondition
ObjectDisposedException

The object has already been disposed.

The size of the hash value depends on the hash algorithm it is computed for. For example, the size of the hash for the HMACSHA384 algorithm is 384 bits, and the size of the hash for the HMACSHA256 algorithm is 256 bits. You can obtain the size of the hash in bits by calling the HashSize property. For more information about hash codes, see Ensuring Data Integrity with Hash Codes.

The following example calculates the RIPEMD160 hash for all files in a directory.


using System;
using System.IO;
using System.Security.Cryptography;
using System.Windows.Forms;

public class HashDirectory
{

    [STAThreadAttribute]
    public static void Main(String[] args)
    {
        string directory = "";
        if (args.Length < 1)
        {
            FolderBrowserDialog fbd = new FolderBrowserDialog();
            DialogResult dr = fbd.ShowDialog();
            if (dr == DialogResult.OK)
                directory = fbd.SelectedPath;
            else
            {
                Console.WriteLine("No directory selected.");
                return;
            }
        }
        else
            directory = args[0];
        try
        {
            // Create a DirectoryInfo object representing the specified directory.
            DirectoryInfo dir = new DirectoryInfo(directory);
            // Get the FileInfo objects for every file in the directory.
            FileInfo[] files = dir.GetFiles();
            // Initialize a RIPE160 hash object.
            RIPEMD160 myRIPEMD160 = RIPEMD160Managed.Create();
            byte[] hashValue;
            // Compute and print the hash values for each file in directory.
            foreach (FileInfo fInfo in files)
            {
                // Create a fileStream for the file.
                FileStream fileStream = fInfo.Open(FileMode.Open);
                // Be sure it's positioned to the beginning of the stream.
                fileStream.Position = 0;
                // Compute the hash of the fileStream.
                hashValue = myRIPEMD160.ComputeHash(fileStream);
                // Write the name of the file to the Console.
                Console.Write(fInfo.Name + ": ");
                // Write the hash value to the Console.
                PrintByteArray(hashValue);
                // Close the file.
                fileStream.Close();
            }
            return;
        }
        catch (DirectoryNotFoundException)
        {
            Console.WriteLine("Error: The directory specified could not be found.");
        }
        catch (IOException)
        {
            Console.WriteLine("Error: A file in the directory could not be accessed.");
        }
    }
    // Print the byte array in a readable format.
    public static void PrintByteArray(byte[] array)
    {
        int i;
        for (i = 0; i < array.Length; i++)
        {
            Console.Write(String.Format("{0:X2}", array[i]));
            if ((i % 4) == 3) Console.Write(" ");
        }
        Console.WriteLine();
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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