How to Compute an MD5 Hash in VB.NET (System.Security.Cryptography)

Recently I was writing a password generator and needed to compute an MD5 hash. In PHP I can just call md5() to get an MD5 hash, but I had never actually tried MD5 in VB. I was worried that .NET might not have any MD5 support, in which case I would have to write it myself…. Orz. Luckily, when I checked MSDN, it turned out to be there. The process was a bit of a hassle, but fortunately MSDN provides a getMD5hash function, so I simply reused it.

The following function is taken from MSDN; I’m mentioning that up front.

P.S. To use this function, you need to import System, System.Text, and System.Security.Cryptography.

Imports System
Imports System.Security.Cryptography
Imports System.Text

If you use another .NET language, you can also check MSDN; they have ready-made functions there (in the examples section). http://msdn.microsoft.com/zh-tw/library/system.security.cryptography.md5.aspx

Function getMd5Hash(ByVal input As String) As String    'MD5 hash function, taken from MSDN
	' Create an MD5 object
	Dim md5Hasher As MD5 = MD5.Create()

	' Convert input to an MD5 hash and return it as Bytes. ComputeHash only accepts a Bytes-type argument, so the input must first be converted to Bytes.
	Dim data As Byte() = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input))

	' Create a StringBuilder object
	Dim sBuilder As New StringBuilder()

	' Convert the Bytes to a String, storing them in hexadecimal
	Dim i As Integer
	For i = 0 To data.Length - 1
		sBuilder.Append(data(i).ToString("x2"))
	Next i

	'Return
	Return sBuilder.ToString()

End Function