VBNETTest.vb

' 参考サイト: http://msdn.microsoft.com/ja-jp/library/system.security.cryptography.tripledes(v=VS.71).aspx

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

Class VBNETTest
	Public Shared Sub Main()
		Dim keyBytesBase64 = System.Convert.FromBase64String("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx")
		Dim i As Integer
		Dim keyBytes(23) As Byte

		For i=0 to 23
			keyBytes(i) = keyBytesBase64(i)
		Next
		EnDecryptData("VBNETTest.vb", "crypted.txt", keyBytes, Nothing, True)
		EnDecryptData("crypted.txt", "plain.txt", keyBytes, Nothing, False)
	End Sub

	' inNameのファイルをTripleDES(tdesKey, tdesIV, Mode=ECB)で暗号化してoutNameファイルに保存する
	Public Shared Sub EncryptData(inName As String, outName As String, tdesKey() As Byte, tdesIV() As Byte)
		EnDecryptData(inName, outName, tdesKey, tdesIV, True)
	End Sub

	' inNameのファイルをTripleDES(tdesKey, tdesIV, Mode=ECB)で復号化してoutNameファイルに保存する
	Public Shared Sub DecryptData(inName As String, outName As String, tdesKey() As Byte, tdesIV() As Byte)
		EnDecryptData(inName, outName, tdesKey, tdesIV, False)
	End Sub

	Public Shared Sub EnDecryptData(inName As String, outName As String, tdesKey() As Byte, tdesIV() As Byte, isEncrypt As Boolean)
		'Create the file streams to handle the input and output files.
		Dim fin As New FileStream(inName, FileMode.Open, FileAccess.Read)
		Dim fout As New FileStream(outName, FileMode.OpenOrCreate, _
		FileAccess.Write)
		fout.SetLength(0)

		'Create variables to help with read and write.
		Dim bin(100) As Byte 'This is intermediate storage for the encryption.
		Dim rdlen As Long = 0 'This is the total number of bytes written.
		Dim totlen As Long = fin.Length 'This is the total length of the input file.
		Dim len As Integer 'This is the number of bytes to be written at a time.
		Dim tdes As New TripleDESCryptoServiceProvider()
		tdes.Mode = CipherMode.ECB
		Dim encStream As CryptoStream
		If isEncrypt Then
			encStream = New CryptoStream(fout, tdes.CreateEncryptor(tdesKey, tdesIV), CryptoStreamMode.Write)
		Else
			encStream = New CryptoStream(fout, tdes.CreateDecryptor(tdesKey, tdesIV), CryptoStreamMode.Write)
		End If

		'Read from the input file, then encrypt and write to the output file.
		While rdlen < totlen
			len = fin.Read(bin, 0, 100)
			encStream.Write(bin, 0, len)
			rdlen = rdlen + len
		End While

		encStream.Close()
	End Sub

End Class