Simple Utility to Calculate File Hashes
I have to download various files from time-to-time, and it's nice when websites provide checksum hashes so I can validate that the file I just downloaded matches the version on the server. (ON a related note, I wrote a blog several years ago which showed how to create a provider for the IIS FTP service which automatically creates checksum files when files are uploaded to a server; see my Automatically Creating Checksum Files for FTP Uploads blog post for the details.)
In order to calculate hashes for files that I have downloaded, several years ago I wrote a simple command-line application for Windows which uses several of the built-in algorithms in .NET's System.Security.Cryptography. And while I realize that there are probably other tools that provide this same functionality, I have used this little utility for years, and I've had several people ask me for copies. With that in mind, I thought that it might make a nice blog topic if I shared the code with everyone. (Note: It's a really simple sample; the .NET framework does all the real work for this application.)
Without further fanfare, here's the source code. In order to use this code sample, you need to create a new C# project in Visual Studio and choose the Console Application template. When the new project opens, replace the template's code with the following:
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Security.Cryptography;
class Hash
{
static void Main(string[] args)
{
// Verify the correct number of command-line arguments.
if (args.Length != 2)
{
// Show the help message if an incorrect number of arguments was specified.
ShowHelp();
return;
}
else
{
byte[] hashValue = null;
// Verify that the specified file exists.
if (!File.Exists(args[1]))
{
// Show the help message if a non-existent filename was specified.
ShowHelp();
return;
}
else
{
try
{
// Create a fileStream for the file.
FileStream fileStream = File.OpenRead(args[1]);
// Be sure it's positioned to the beginning of the stream.
fileStream.Position = 0;
// Use the specified hash algorithm.
switch (args[0].ToUpper())
{
case "MD5":
// Compute the MD5 hash of the fileStream.
hashValue = MD5.Create().ComputeHash(fileStream);
break;
case "SHA1":
// Compute the SHA1 hash of the fileStream.
hashValue = SHA1.Create().ComputeHash(fileStream);
break;
case "SHA256":
// Compute the SHA256 hash of the fileStream.
hashValue = SHA256.Create().ComputeHash(fileStream);
break;
case "SHA384":
// Compute the SHA384 hash of the fileStream.
hashValue = SHA384.Create().ComputeHash(fileStream);
break;
case "SHA512":
// Compute the SHA512 hash of the fileStream.
hashValue = SHA512.Create().ComputeHash(fileStream);
break;
case "BASE64":
// Compute the BASE64 hash of the fileStream.
byte[] binaryData = new Byte[fileStream.Length];
long bytesRead = fileStream.Read(binaryData, 0, (int)fileStream.Length);
if (bytesRead != fileStream.Length)
{
throw new Exception(String.Format("Number of bytes read ({0}) does not match file size ({1}).", bytesRead, fileStream.Length));
}
string base64String = System.Convert.ToBase64String(binaryData, 0, binaryData.Length);
Console.WriteLine("File: {0}\r\nBASE64 Hash: {1}", fileStream.Name, base64String);
hashValue = null;
break;
default:
// Display the help message if an unrecognized hash algorithm was specified.
ShowHelp();
return;
}
if (hashValue != null)
{
// Write the hash value to the Console.
PrintHashData(args[0].ToUpper(), fileStream.Name, hashValue);
}
// Close the file.
fileStream.Close();
}
catch (Exception ex)
{
Console.WriteLine("Error: {0}", ex.Message);
}
}
}
}
// Display the help message.
private static void ShowHelp()
{/> Console.WriteLine("HASH.exe <hash algorithm> <file name>\n\n" +
"\tWhere <hash algorithm> is one of the following:\n" +
"\t\tBASE64\n\t\tMD5\n\t\tSHA1\n\t\tSHA256\n\t\tSHA384\n\t\tSHA512\n");
}
// Print the hash data in a readable format.
private static void PrintHashData(string algorithm, string fileName, byte[] array)
{
Console.Write("File: {0}\r\n{1} Hash: ", fileName,algorithm);
for (int i = 0; i < array.Length; i++)
{
Console.Write(String.Format("{0:X2}", array[i]));
}
Console.WriteLine();
}/>}
When you compile and run the application, you will see following help message when you specify no command-line parameters:
HASH.exe <hash algorithm> <file name>
Where <hash algorithm> is one of the following:
BASE64
MD5
SHA1
SHA256
SHA384
SHA512
When you specify one of the supported hashing algorithms and a filename, the application will display something like the following example:
C:\>hash.exe SHA1 foobar.zip
File: C:\foobar.zip
SHA1 Hash: 57686F6120447564652C20426F6220526F636B73
That's all there is to it. As I mentioned earlier, it's a pretty simple sample. ;-]