Generate MD5 hash of a string in C#

This post will discuss how to generate the MD5 hash of a string in C#.

In C#, you can use the MD5 class from System.Security.Cryptography namespace to compute the MD5 hash of the input data. Following are the steps to calculate the MD5 hash value of a string –

Initialize the MD5 hash object with MD5.Create() method.
Convert the given string into a byte array using the Encoding.GetBytes() method.
Compute the hash value for the specified byte array with the ComputeHash() method.
Transform the byte array to produce a 32-character, hexadecimal-formatted hash string.

The following example demonstates this by calculating the SHA-256 hash for a given string.

using System;

using System.Text;

using System.Security.Cryptography;

public class Example

{

static string ComputeMD5(string s)

{

StringBuilder sb = new StringBuilder();

// Initialize a MD5 hash object

using (MD5 md5 = MD5.Create())

{

// Compute the hash of the given string

byte[] hashValue = md5.ComputeHash(Encoding.UTF8.GetBytes(s));

// Convert the byte array to string format

foreach (byte b in hashValue) {

sb.Append($"{b:X2}");

}

return sb.ToString();

}

public static void Main()

{

string hash = ComputeMD5("Hello");

Console.WriteLine(hash); // 8B1A9953C4611296A827ABF8C47804D7

}

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Here’s an even shorter version of the above code that uses the BitConverter.ToString() method:

using System;

using System.Text;

using System.Security.Cryptography;

public class Example

{

static string ComputeMD5(string s)

{

using (MD5 md5 = MD5.Create())

{

return BitConverter.ToString(md5.ComputeHash(Encoding.UTF8.GetBytes(s)))

.Replace("-", "");

}

public static void Main()

{

string hash = ComputeMD5("Hello");

Console.WriteLine(hash); // 8B1A9953C4611296A827ABF8C47804D7

}

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If you’re using .NET 5 and above, you can use the Convert.ToHexString() method to convert the byte array to its equivalent string representation.

using System;

using System.Text;

using System.Security.Cryptography;

public class Example

{

static string ComputeMD5(string s)

{

using (MD5 md5 = MD5.Create())

{

byte[] hashValue = md5.ComputeHash(Encoding.UTF8.GetBytes(s));

return Convert.ToHexString(hashValue);

}

public static void Main()

{

string hash = ComputeMD5("Hello");

Console.WriteLine(hash); // 8B1A9953C4611296A827ABF8C47804D7

}

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Important Note: To avoid collision problems associated with the MD5 hash, Microsoft recommends using the SHA-256 hash (or SHA-512 hash) over MD5.

That’s all about generating the MD5 hash of a string in C#.

Generate MD5 hash of a string in C#

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