Lianja

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.

Lianja

llSuccess = .F.

// 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.
loJpgBytes = createobject("CkBinData")
llSuccess = loJpgBytes.LoadFile("qa_data/jpg/starfish.jpg")
if (llSuccess <> .T.) then
    ? "Failed to load JPG file."
    release loJpgBytes
    return
endif

// 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.)
? loJpgBytes.GetEncoded("base64_mime")

// Sample base64_mime JPG data:

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

loCrypt = createobject("CkCrypt2")

// Specify the encryption to be used.
// First we'll do AES-128 CBC
loCrypt.CryptAlgorithm = "aes"
loCrypt.CipherMode = "cbc"
loCrypt.KeyLength = 128

lcIvHex = "000102030405060708090A0B0C0D0E0F"
loCrypt.SetEncodedIV(lcIvHex,"hex")

lcKeyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
loCrypt.SetEncodedKey(lcKeyHex,"hex")

// Do the in-place 128-bit AES CBC encryption.
// The contents of jpgBytes are replaced with the encrypted bytes.
llSuccess = loCrypt.EncryptBd(loJpgBytes)
if (llSuccess <> .T.) then
    ? loCrypt.LastErrorText
    release loJpgBytes
    release loCrypt
    return
endif

// Examine the JPG bytes again.  The bytes should be different because they are encrypted:
? loJpgBytes.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:
llSuccess = loCrypt.DecryptBd(loJpgBytes)
if (llSuccess <> .T.) then
    ? loCrypt.LastErrorText
    release loJpgBytes
    release loCrypt
    return
endif

? loJpgBytes.GetEncoded("base64_mime")

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

// ----------------------------------------------------------------------------------
// To do chacha20 encryption, just change the settings:

loCrypt.CryptAlgorithm = "chacha20"
loCrypt.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.
loCrypt.InitialCount = 22

llSuccess = loCrypt.EncryptBd(loJpgBytes)
// jpgBytes now contains chacha20 encrypted bytes.

llSuccess = loCrypt.DecryptBd(loJpgBytes)
// jpgBytes is now restored back to the original unencrypted by bytes.

// Save the bytes to a file..
llSuccess = loJpgBytes.WriteFile("qa_output/starfish.jpg")

? "Success."


release loJpgBytes
release loCrypt