Class AES_Test Inherits Application

Const kEditClear = "&Löschen"

Const kFileQuit = "Beenden"

Const kFileQuitShortcut = ""

End Class

Class frmMain Inherits Window

EventHandler Sub Close() quit End EventHandler

Function DecryptAES(key as string, iv as string, SourceFile as FolderItem, DestFile as FolderItem, optional Blocksize as Integer = 160000) As Boolean // decrypt file with AES and CBC BlockSize = BlockSize - (BlockSize mod 16) if BlockSize <=0 then BlockSize = 16 end dim a as AESMBS = NewAES(key) if a = nil then Return false dim bi as BinaryStream = sourcefile.OpenAsBinaryFile(false) if bi = nil then Return false dim bo as BinaryStream = destfile.CreateBinaryFile("") if bo = nil then Return false dim IVectorOffset as integer = 0 dim IVector as MemoryBlock = iv dim newIV as new MemoryBlock(16) dim FileLength as int64 = SourceFile.Length dim BytesToProcess as int64 = 0 dim aktPos as int64 = 0 dim aktBlockLength as int64 dim data as string ="" do aktPos = bi.Position BytesToProcess = FileLength - aktPos data = bi.Read(BlockSize) dim idata as MemoryBlock = data // pick last 16 bytes of encrypted data as initialization vector of next block newIV = idata.RightB(16) aktBlockLength = LenB(idata) if aktBlockLength > 0 then a.DecryptCBC(idata, lenb(data), IVector, nil, 0, 0) // assign initialization vector for next block IVector = newIV if BytesToProcess <= BlockSize then // Last block // check padding byte dim wegDamit as integer = asc(idata.RightB(1)) // copy bytes without padding if BytesToProcess - wegDamit > 0 then dim RestData as string = idata.LeftB(BytesToProcess - wegDamit) bo.Write RestData end if else // write decrypted bytes bo.Write idata end if end if loop until aktBlockLength = 0 bo.Close bi.Close Return true End Function

Sub DecryptFile() dim key as string = "1234567890123456ABCDEFGHIJKLMNOP" dim iv as string = "6543210987654321" dim Filename as string = txFileName.Text dim Extension as string = "." + txExtension.Text dim sourceFile as FolderItem = SpecialFolder.Desktop.Child(Filename +".aes") dim decryptedFile as FolderItem = SpecialFolder.Desktop.Child(Filename +"_decrypted" + Extension) if sourceFile.Exists = false then MsgBox "File not found: " + sourceFile.Name return end if if DecryptAES(key, iv, sourceFile, decryptedFile) then MsgBox "Fertig !" end if End Sub

Function EncryptAES(key as string, iv as string, sourcefile as FolderItem, destfile as FolderItem, optional BlockSize as integer = 160000) As Boolean // encrypt file with AES and CBC BlockSize = BlockSize - (BlockSize mod 16) if BlockSize <=0 then BlockSize = 16 end dim a as AESMBS = NewAES(key) if a = nil then Return false dim bi as BinaryStream = sourcefile.OpenAsBinaryFile(false) if bi = nil then Return false dim bo as BinaryStream = destfile.CreateBinaryFile("") if bo = nil then Return false dim IVectorOffset as integer = 0 dim IVector as MemoryBlock = iv dim newIV as new MemoryBlock(16) dim FileLength as int64 = SourceFile.Length dim BytesToProcess as int64 = 0 dim aktPos as int64 = 0 dim aktBlockLength as int64 dim data as string ="" do aktPos = bi.Position BytesToProcess = FileLength - aktPos data = bi.Read(BlockSize) dim idata as MemoryBlock = data dim PaddingValue as integer = 16 - (BytesToProcess Mod 16) aktBlockLength = LenB(idata) if aktBlockLength > 0 then if BytesToProcess <= BlockSize then // add padding for last block dim RestData as new MemoryBlock(BytesToProcess + PaddingValue) RestData = idata.LeftB(BytesToProcess) + new MemoryBlock(PaddingValue) for i as integer = BytesToProcess to BytesToProcess + PaddingValue -1 RestData.byte(i) = PaddingValue next i a.EncryptCBC(RestData, BytesToProcess + PaddingValue, IVector, nil, 0, 0) bo.Write RestData else a.EncryptCBC(idata, lenb(data), IVector, nil, 0, 0) bo.Write idata // Take last bytes as initialization vector of next block IVector = idata.RightB(16) end if end if loop until aktBlockLength = 0 bo.Close bi.Close Return true End Function

Sub EncryptFile() dim key as string = "1234567890123456ABCDEFGHIJKLMNOP" dim iv as string = "6543210987654321" dim Filename as string = txFileName.Text dim Extension as string = "." + txExtension.Text dim sourceFile as FolderItem = SpecialFolder.Desktop.Child(Filename+Extension) dim encryptedFile as FolderItem = SpecialFolder.Desktop.Child(Filename+".aes") if sourceFile.Exists = false then MsgBox "File not found: " + Filename + extension return end if if EncryptAES(key, iv, sourceFile, encryptedFile) then MsgBox "Fertig!" end if End Sub

Function NewAES(key as string) As AESMBS dim a as new AESMBS // all keys should be UTF-8 key = ConvertEncoding(key, encodings.ascii) //dim bits as integer = 0 dim l as integer = lenb(key) // pad key to required length for 16, 24 or 32 bit key if l>32 then key = leftb(key,32) elseif l>24 then while lenb(key)<32 key = key + " " wend elseif l>16 then while lenb(key)<24 key = key + " " wend else while lenb(key)<16 key = key + " " wend end if if a.SetKey(key) then Return a end if End Function

End Class

MenuBar MenuBar1

End MenuBar