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(VB.NET) Example for both AES-128 and ChaCha20 to Encrypt Binary DataDemonstrates the use of the new EncryptBd and DecryptBd methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt binary bytes. Note: This example requires Chilkat v9.5.0.67 or greater.
' This example assumes the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. ' Load a small JPG file to be encrypted/decrypted. Dim jpgBytes As New Chilkat.BinData Dim success As Boolean = jpgBytes.LoadFile("qa_data/jpg/starfish.jpg") If (success <> True) Then Debug.WriteLine("Failed to load JPG file.") Exit Sub End If ' Show the unencrypted JPG bytes in Base64 format. ' (The "base64_mime" encoding was added in Chilkat v9.5.0.67. ' The "base64" encoding emits a single line of base64, whereas ' "base64_mime" will emit multi-line base64 as it would appear ' in MIME.) Debug.WriteLine(jpgBytes.GetEncoded("base64_mime")) ' Sample base64_mime JPG data: ' /9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA ' AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB ' AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA ' MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM ' ... Dim crypt As New Chilkat.Crypt2 ' Specify the encryption to be used. ' First we'll do AES-128 CBC crypt.CryptAlgorithm = "aes" crypt.CipherMode = "cbc" crypt.KeyLength = 128 Dim ivHex As String = "000102030405060708090A0B0C0D0E0F" crypt.SetEncodedIV(ivHex,"hex") Dim keyHex As String = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F" crypt.SetEncodedKey(keyHex,"hex") ' Do the in-place 128-bit AES CBC encryption. ' The contents of jpgBytes are replaced with the encrypted bytes. success = crypt.EncryptBd(jpgBytes) If (success <> True) Then Debug.WriteLine(crypt.LastErrorText) Exit Sub End If ' Examine the JPG bytes again. The bytes should be different because they are encrypted: Debug.WriteLine(jpgBytes.GetEncoded("base64_mime")) ' Sample base64_mime encrypted JPG data: ' sbz0babt1WCkQf5xKMdg/baZAcUBO5GVUUDF2BjVqmd+HrqKN+t6hAcqakL/bdo0q9hYmow0Tp1e ' AQ9V9DOiifQUZqWVkR+kL/c45bq8JGFDvgNl0djPt+yYhV789IB/fPH0upx+/ad++WNOlv1IxGMr ' Y1x1oERU/IsiEzafUJdI4kZ6FQo2IPGMF/Rm1h79I7hP1yYUFxvJyz+PzaySAUH1nLsNHyDVY5VY ' O90aH3steRSYbz8C8UF9wQ3qqEIXQNnnixvoNDnmHyY39VoVBI5F6rnPwYDfAk2t8tmuryFqvwAu ' ... ' Decrypt to restore back to the original: success = crypt.DecryptBd(jpgBytes) If (success <> True) Then Debug.WriteLine(crypt.LastErrorText) Exit Sub End If Debug.WriteLine(jpgBytes.GetEncoded("base64_mime")) ' /9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA ' AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB ' AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA ' MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM ' ... ' ---------------------------------------------------------------------------------- ' To do chacha20 encryption, just change the settings: crypt.CryptAlgorithm = "chacha20" crypt.KeyLength = 256 ' The initial count is the initial block counter for the chacha20 algorithm. ' It can be any integer, but must be set to the same when decrypting. crypt.InitialCount = 22 success = crypt.EncryptBd(jpgBytes) ' jpgBytes now contains chacha20 encrypted bytes. success = crypt.DecryptBd(jpgBytes) ' jpgBytes is now restored back to the original unencrypted by bytes. ' Save the bytes to a file.. success = jpgBytes.WriteFile("qa_output/starfish.jpg") Debug.WriteLine("Success.") |
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