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

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.

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

# 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.
set jpgBytes [new_CkBinData]

set success [CkBinData_LoadFile $jpgBytes "qa_data/jpg/starfish.jpg"]
if {$success != 1} then {
    puts "Failed to load JPG file."
    delete_CkBinData $jpgBytes
    exit
}

# 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.)
puts [CkBinData_getEncoded $jpgBytes base64_mime]

# Sample base64_mime JPG data:

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

set crypt [new_CkCrypt2]

# Specify the encryption to be used.
# First we'll do AES-128 CBC
CkCrypt2_put_CryptAlgorithm $crypt "aes"
CkCrypt2_put_CipherMode $crypt "cbc"
CkCrypt2_put_KeyLength $crypt 128

set ivHex "000102030405060708090A0B0C0D0E0F"
CkCrypt2_SetEncodedIV $crypt $ivHex "hex"

set keyHex "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F"
CkCrypt2_SetEncodedKey $crypt $keyHex "hex"

# Do the in-place 128-bit AES CBC encryption.
# The contents of jpgBytes are replaced with the encrypted bytes.
set success [CkCrypt2_EncryptBd $crypt $jpgBytes]
if {$success != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkBinData $jpgBytes
    delete_CkCrypt2 $crypt
    exit
}

# Examine the JPG bytes again.  The bytes should be different because they are encrypted:
puts [CkBinData_getEncoded $jpgBytes 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:
set success [CkCrypt2_DecryptBd $crypt $jpgBytes]
if {$success != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkBinData $jpgBytes
    delete_CkCrypt2 $crypt
    exit
}

puts [CkBinData_getEncoded $jpgBytes base64_mime]

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

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

CkCrypt2_put_CryptAlgorithm $crypt "chacha20"
CkCrypt2_put_KeyLength $crypt 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.
CkCrypt2_put_InitialCount $crypt 22

set success [CkCrypt2_EncryptBd $crypt $jpgBytes]
# jpgBytes now contains chacha20 encrypted bytes.

set success [CkCrypt2_DecryptBd $crypt $jpgBytes]
# jpgBytes is now restored back to the original unencrypted by bytes.

# Save the bytes to a file..
set success [CkBinData_WriteFile $jpgBytes "qa_output/starfish.jpg"]

puts "Success."

delete_CkBinData $jpgBytes
delete_CkCrypt2 $crypt