| 11/13/2006
WinFormsEncryptPasswordVB2005.zip
This article and
source code explain how to use the .NET Cryptography
MD5CryptoServiceProvider method to
encrypt a string used as a password in a Windows Forms application.
The .NET MD5CryptoServiceProvider
computes the
MD5 hash value for input data using the implementation provided
by the cryptographic service provider.
Hash functions map binary strings of an
arbitrary length to small binary strings of a fixed length. A
cryptographic hash function has the property that it is
computationally infeasible to find two distinct inputs that hash to
the same value; that is, hashes of two sets of data should match if
the corresponding data also matches. Small changes to the data
result in large, unpredictable changes in the hash.
The hash size for the MD5 algorithm is 128 bits.
Included in the source
code is a class named EncryptPassword. This class contains a method
named 'EncryptString' that uses the Text namespace's UnicodeEncoding
method to convert a string passed into the class into a Byte array,
encrypts the string using the Cryptography namespace's
MD5CryptoServiceProvider and returns the encrypted string to the
caller.
Code Example
Public Class
EncryptPassword
Public
Shared Function
EncryptString(ByVal sourceString
As
String) As
String
' Declare a variable of type Byte array
named sourceStringToBytes.
' Call a UnicodeEncoding object's
GetBytes method, passing it the sourceString.
' Assign the resulting byte array to the
sourceStringToBytes variable.
Dim sourceStringToBytes
As Byte()
= (New UnicodeEncoding()).GetBytes(sourceString)
' Declare a variable of type Byte array
named hashedBytes.
' Call a MD5CryptoServiceProvider
objects's ComputeHash method
' passing it the sourceStringToBytes
array.
' Assign the resulting byte array to the
hashedBytes variable.
Dim hashedBytes
As Byte()
= New
MD5CryptoServiceProvider().ComputeHash(sourceStringToBytes)
' Use the BitConverter class's shared
ToString method to return
' the bytes encrypted as a string.
Return
BitConverter.ToString(hashedBytes)
End
Function
End Class
The Windows Forms examples demonstrates
the EncryptPassword class in action.
Behind the test form are two methods
that use the EncryptPassword class.
The first, 'EncryptAndSave', takes a
password entered by a user, encrypts it with the EncryptPassword
class, then saves the encrypted password to file.
The second, 'ValidatePassword', takes a
password entered by a user, encrypts it with the EncryptPassword
class, retrieves a encrypted password from file, and validates that
the password provided by the user matches the password stored to
file.
For more information visit the links
below:
MD5CryptoServiceProvider Class
Click the link above to download Visual
Basic source code in a Visual Studio solution which
demonstrates how to
how to use the .NET Cryptography
MD5CryptoServiceProvider method to
encrypt a string used as a password in a Windows Forms application.
Source code for Visual Basic 2002 and
Visual Basic 2003 can be found at:
Windows Forms Password Encryption With Visual Basic 2002 and 2003
Get Dot Net Code is a web site full of free and pay for use Visual Basic source code for Visual Basic programmers.
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