How do I create an MD5 hash digest from a text file?
17,854
Solution 1
Here's the routine I'm currently using.
using System.Security.Cryptography;
public string HashFile(string filePath)
{
using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read))
{
return HashFile(fs);
}
}
public string HashFile( FileStream stream )
{
StringBuilder sb = new StringBuilder();
if( stream != null )
{
stream.Seek( 0, SeekOrigin.Begin );
MD5 md5 = MD5CryptoServiceProvider.Create();
byte[] hash = md5.ComputeHash( stream );
foreach( byte b in hash )
sb.Append( b.ToString( "x2" ) );
stream.Seek( 0, SeekOrigin.Begin );
}
return sb.ToString();
}
Solution 2
Short and to the point. filename
is your text file's name:
using (var md5 = MD5.Create())
{
return BitConverter.ToString(md5.ComputeHash(File.ReadAllBytes(filename))).Replace("-", "");
}
Solution 3
This can be achieved by GetHashCode
with overloads, allowing to pass either a filePath, a StreamReader or a Stream:
private static string GetHashCode(string filePath, HashAlgorithm cryptoService = null)
=> GetHashCode(fStream: new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite), cryptoService);
private static string GetHashCode(StreamReader fileStreamReader, HashAlgorithm cryptoService = null)
=> GetHashCode(fileStreamReader.BaseStream, cryptoService);
/// <summary>
/// Compute hash code for file.
/// </summary>
/// <param name="fStream"></param>
/// <param name="cryptoService">This can be either MD5, SHA1, SHA256, SHA384 or SHA512</param>
/// <returns>Hash string</returns>
private static string GetHashCode(Stream fStream, HashAlgorithm cryptoService = null)
{
// create or use the instance of the crypto service provider
// this can be either MD5, SHA1, SHA256, SHA384 or SHA512
using (cryptoService ??= System.Security.Cryptography.SHA512.Create())
{
using var tmpStream = fStream;
var hash = cryptoService.ComputeHash(tmpStream);
var hashString = Convert.ToBase64String(hash);
return hashString.TrimEnd('=');
}
} // method
Usage:
WriteLine("Default Sha512 Hash Code : {0}", GetHashCode(FilePath));
Or:
WriteLine("MD5 Hash Code : {0}", GetHashCode(FilePath, new MD5CryptoServiceProvider()));
WriteLine("SHA1 Hash Code : {0}", GetHashCode(FilePath, new SHA1CryptoServiceProvider()));
WriteLine("SHA256 Hash Code: {0}", GetHashCode(FilePath, new SHA256CryptoServiceProvider()));
WriteLine("SHA384 Hash Code: {0}", GetHashCode(FilePath, new SHA384CryptoServiceProvider()));
WriteLine("SHA512 Hash Code: {0}", GetHashCode(FilePath, new SHA512CryptoServiceProvider()));
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Author by
Craig Schwarze
A software development manager and architect, with extensive experience in enterprise application development using a range of technologies, mostly in the Microsoft technical space. Find me on LinkedIn!
Updated on April 15, 2022Comments
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Craig Schwarze about 2 years
Using C#, I want to create an MD5 hash of a text file. How can I accomplish this?
Update: Thanks to everyone for their help. I've finally settled upon the following code -
// Create an MD5 hash digest of a file public string MD5HashFile(string fn) { byte[] hash = MD5.Create().ComputeHash(File.ReadAllBytes(fn)); return BitConverter.ToString(hash).Replace("-", ""); }
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Craig Schwarze over 14 yearsThat's perfect roufamatic. Does it return a 32 digit hex?
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Craig Schwarze over 14 yearsJust tested the function out, and it does exactly what I need - many thanks again.
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roufamatic over 14 yearsIf you don't need to reuse the stream you can of course remove all that code. This used to be in a pipeline of sorts so that the stream could be hashed first, then gzipped. Now I mostly just care about the hash, hence the shortcut.
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Craig Schwarze over 14 yearsToBase64String doesn't return what I want. However, BitConverter.ToString around the byte array does the trick
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Matt over 2 yearsGood solution! I suggest a little improvement: Make the 2nd parameter nullable i.e.
HashAlgorithm cryptoService = null
and then add a default provider like so:using (cryptoService ??= System.Security.Cryptography.SHA512.Create())
- or if you prefer, you can use MD5 too (but I would not recommend it). This will simplify usage while keeping maximum flexibility (you are still able to add the provider of your choice). -
Matt over 2 yearsHint (for those who need it): In case you need a StreamReader (fileStreamReader) instead of a filepath as a parameter, you can create an overload of this function where you do like
using var fileStream = fileStreamReader.BaseStream;
.