B4X

Example for both AES-128 and ChaCha20 to Encrypt Binary Data

See more Encryption Examples

Demonstrates 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.

B4X

Dim success As Boolean = False

'  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 ChilkatBinData
jpgBytes.Initialize
success = jpgBytes.LoadFile("qa_data/jpg/starfish.jpg")
If success <> True Then
    Log("Failed to load JPG file.")
    Return
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.)
Log(jpgBytes.GetEncoded("base64_mime"))

'  Sample base64_mime JPG data:

'  	/9j/4AAQSkZJRgABAgEASABIAAD/7Q18UGhvdG9zaG9wIDMuMAA4QklNA+0AAAAAABAASAAAAAEA
'  	AQBIAAAAAQABOEJJTQPzAAAAAAAIAAAAAAAAAAE4QklNBAoAAAAAAAEAADhCSU0nEAAAAAAACgAB
'  	AAAAAAAAAAI4QklNA/UAAAAAAEgAL2ZmAAEAbGZmAAYAAAAAAAEAL2ZmAAEAoZmaAAYAAAAAAAEA
'  	MgAAAAEAWgAAAAYAAAAAAAEANQAAAAEALQAAAAYAAAAAAAE4QklNBBQAAAAAAAQAAAABOEJJTQQM
'  	...

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

'  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
    Log(crypt.LastErrorText)
    Return
End If


'  Examine the JPG bytes again.  The bytes should be different because they are encrypted:
Log(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
    Log(crypt.LastErrorText)
    Return
End If


Log(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")

Log("Success.")