Encrypting and decrypting from file to memory (VB streaming example)

Here are is an example for VB that demonstrates encryption from file to memory in a streaming fashion. It shows how to use the Rijndael algorithm.

Visual Basic Copy Code

Visual Basic	Copy Code
' This example encrypts data using the Rijndael method from a file to memory in 8K (8192 byte) chunks. Const CHUNKSIZE = 8192 Dim xEncryptor As New XceedEncryption Call xEncryptor.License( "your license key" ) Dim lOffSet As Long Dim lFileSize As Long Dim vaBytesRead As Variant Dim vaEncrypted As Variant Set xEncryptor. EncryptionMethod = New XceedRijndaelEncryptionMethod lOffSet = 0 ' We must track the current offset On Error Resume Next Call xEncryptor. EncryptionMethod.SetSecretKeyFromPassPhrase("This is a weak pass phrase!", 128) lFileSize = FileLen("c:\temp\source.txt") While lOffSet < lFileSize 'bEndOfData will be true if the current offset + CHUNKSIZE exceeds the end of the file. vaEncrypted = xEncryptor.ReadFile("c:\temp\source.txt", lOffSet, CHUNKSIZE, efpEncrypt, _ (lOffSet + CHUNKSIZE >= lFileSize), vaBytesRead) If Not IsEmpty(vaEncrypted) Then ' You now have a portion of encrypted data you can use. ' For example, transfer it, process it, etc. End If lOffSet = lOffSet + vaBytesRead Wend If Err.Number = 0 Then MsgBox "Finished encrypting file to memory." Else MsgBox Err.Number & " " & Err.Description End If



' This example encrypts data using the Rijndael method from a file to memory in 8K (8192 byte) chunks. 

Const CHUNKSIZE = 8192

Dim xEncryptor As New XceedEncryption

Call xEncryptor.License( "your license key" ) 

Dim lOffSet As Long
Dim lFileSize As Long
Dim vaBytesRead As Variant
Dim vaEncrypted As Variant 

Set xEncryptor. EncryptionMethod = New XceedRijndaelEncryptionMethod 

lOffSet = 0 ' We must track the current offset 

On Error Resume Next

Call xEncryptor. EncryptionMethod.SetSecretKeyFromPassPhrase("This is a weak pass phrase!", 128)

lFileSize = FileLen("c:\temp\source.txt") 

While lOffSet < lFileSize
  'bEndOfData will be true if the current offset + CHUNKSIZE exceeds the end of the file. 

  vaEncrypted = xEncryptor.ReadFile("c:\temp\source.txt", lOffSet, CHUNKSIZE, efpEncrypt, _
                                    (lOffSet + CHUNKSIZE >= lFileSize), vaBytesRead)  

  If Not IsEmpty(vaEncrypted) Then 
    ' You now have a portion of encrypted data you can use. 
    ' For example, transfer it, process it, etc. 
  End If 

  lOffSet = lOffSet + vaBytesRead 
Wend 

If Err.Number = 0 Then
  MsgBox "Finished encrypting file to memory." 
Else
  MsgBox Err.Number & " " & Err.Description 
End If