Saturday 8 December 2012

VB.net Encryption and Decyption pssword



Encrypt Process:

Public Function Encrypt(ByVal plainText As String) As String

        Dim passPhrase As String = "Pas5pr@se"
        Dim saltValue As String = "zKqffFs392WuxGMhFkfhYj/HtDDIjSiXnYqMlMMzrNc="

        Dim hashAlgorithm As String = "SHA1"

        Dim passwordIterations As Integer = 2
        Dim initVector As String = "@1B2c3D4e5F6g7H8"
        Dim keySize As Integer = 256

        Dim initVectorBytes As Byte() = Encoding.ASCII.GetBytes(initVector)
        Dim saltValueBytes As Byte() = Encoding.ASCII.GetBytes(saltValue)

        Dim plainTextBytes As Byte() = Encoding.UTF8.GetBytes(plainText)


        Dim password As New PasswordDeriveBytes(passPhrase, saltValueBytes, hashAlgorithm, passwordIterations)

        Dim keyBytes As Byte() = password.GetBytes(keySize \ 8)
        Dim symmetricKey As New RijndaelManaged()

        symmetricKey.Mode = CipherMode.CBC

        Dim encryptor As ICryptoTransform = symmetricKey.CreateEncryptor(keyBytes, initVectorBytes)

        Dim memoryStream As New IO.MemoryStream()
        Dim cryptoStream As New CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write)

        cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length)
        cryptoStream.FlushFinalBlock()
        Dim cipherTextBytes As Byte() = memoryStream.ToArray()
        memoryStream.Close()
        cryptoStream.Close()
        Dim cipherText As String = Convert.ToBase64String(cipherTextBytes)
        Return cipherText
    End Function


Decrypt Process


Public Function Decrypt(ByVal cipherText As String, ByVal salt As String) As String

        Dim passPhrase As String = "Pas5pr@se"
        Dim saltValue As String = "zKqffFs392WuxGMhFkfhYj/HtDDIjSiXnYqMlMMzrNc="
        Dim hashAlgorithm As String = "SHA1"
        Dim passwordIterations As Integer = 2
        Dim initVector As String = "@1B2c3D4e5F6g7H8"
        Dim keySize As Integer = 256
        ' Convert strings defining encryption key characteristics into byte
        ' arrays. Let us assume that strings only contain ASCII codes.
        ' If strings include Unicode characters, use Unicode, UTF7, or UTF8
        ' encoding.
        Dim initVectorBytes As Byte() = Encoding.ASCII.GetBytes(initVector)
        Dim saltValueBytes As Byte() = Encoding.ASCII.GetBytes(saltValue)

        ' Convert our ciphertext into a byte array.
        Dim cipherTextBytes As Byte() = Convert.FromBase64String(cipherText)

        ' First, we must create a password, from which the key will be
        ' derived. This password will be generated from the specified
        ' passphrase and salt value. The password will be created using
        ' the specified hash algorithm. Password creation can be done in
        ' several iterations.
        Dim password As New PasswordDeriveBytes(passPhrase, saltValueBytes, hashAlgorithm, passwordIterations)

        ' Use the password to generate pseudo-random bytes for the encryption
        ' key. Specify the size of the key in bytes (instead of bits).
        Dim keyBytes As Byte() = password.GetBytes(keySize \ 8)

        ' Create uninitialized Rijndael encryption object.
        Dim symmetricKey As New RijndaelManaged()

        ' It is reasonable to set encryption mode to Cipher Block Chaining
        ' (CBC). Use default options for other symmetric key parameters.
        symmetricKey.Mode = CipherMode.CBC

        ' Generate decryptor from the existing key bytes and initialization
        ' vector. Key size will be defined based on the number of the key
        ' bytes.
        Dim decryptor As ICryptoTransform = symmetricKey.CreateDecryptor(keyBytes, initVectorBytes)

        ' Define memory stream which will be used to hold encrypted data.
        Dim memoryStream As New IO.MemoryStream(cipherTextBytes)

        ' Define cryptographic stream (always use Read mode for encryption).
        Dim cryptoStream As New CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read)

        ' Since at this point we don't know what the size of decrypted data
        ' will be, allocate the buffer long enough to hold ciphertext;
        ' plaintext is never longer than ciphertext.
        Dim plainTextBytes As Byte() = New Byte(cipherTextBytes.Length - 1) {}

        ' Start decrypting.
        Dim decryptedByteCount As Integer = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length)

        ' Close both streams.
        memoryStream.Close()
        cryptoStream.Close()
        ' Convert decrypted data into a string.
        ' Let us assume that the original plaintext string was UTF8-encoded.
        Dim plainText As String = Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount)

        ' Return decrypted string.
        Return plainText
    End Function

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