(Tcl) AES and CHACHA20 Encrypt/Decrypt Text

Demonstrates the use of the new EncryptSb and DecryptSb methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt the contents of StringBuilder objects.

Note: This example requires Chilkat v9.5.0.67 or greater.

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load ./chilkat.dll

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# First build a string to be encrypted
set sb [new_CkStringBuilder]

set i 1
while {$i < 10} {
    CkStringBuilder_AppendInt $sb $i
    CkStringBuilder_Append $sb " the quick brown fox jumped over the lazy dog.\r\n"
    set i [expr $i + 1]
}

puts [CkStringBuilder_getAsString $sb]

# The string to be encrypted looks like this:

# 1 the quick brown fox jumped over the lazy dog.
# 2 the quick brown fox jumped over the lazy dog.
# 3 the quick brown fox jumped over the lazy dog.
# 4 the quick brown fox jumped over the lazy dog.
# 5 the quick brown fox jumped over the lazy dog.
# 6 the quick brown fox jumped over the lazy dog.
# ...

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"

# When EncryptSb is called, the contents of the source (sb)
# remains unmodified.  The encrypted bytes are written into bdEncrypted.
# If bdEncrypted already contained data, it is replaced with the encrypted bytes.
set bdEncrypted [new_CkBinData]

set success [CkCrypt2_EncryptSb $crypt $sb $bdEncrypted]
if {$success != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkStringBuilder $sb
    delete_CkCrypt2 $crypt
    delete_CkBinData $bdEncrypted
    exit
}

# Examine the encrypted bytes:
puts [CkBinData_getEncoded $bdEncrypted base64_mime]

# Sample encrypted data:

# 0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
# df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
# EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
# g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
# PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
# 2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
# eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
# H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

# Decrypt to restore back to the original:
set sbOriginal [new_CkStringBuilder]

set success [CkCrypt2_DecryptSb $crypt $bdEncrypted $sbOriginal]
if {$success != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkStringBuilder $sb
    delete_CkCrypt2 $crypt
    delete_CkBinData $bdEncrypted
    delete_CkStringBuilder $sbOriginal
    exit
}

# Examine the original data:
puts [CkStringBuilder_getAsString $sbOriginal]

# ----------------------------------------------------------------------------------
# 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

# EncryptSb completely replaces the contents of bdEncrypted.
set success [CkCrypt2_EncryptSb $crypt $sb $bdEncrypted]

# However.. DecryptSb appends the decrypted text to whatever may
# have already existed within sbOriginal.
set success [CkCrypt2_DecryptSb $crypt $bdEncrypted $sbOriginal]

puts "----"
puts "The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt."
puts [CkStringBuilder_getAsString $sbOriginal]
puts "Success."

delete_CkStringBuilder $sb
delete_CkCrypt2 $crypt
delete_CkBinData $bdEncrypted
delete_CkStringBuilder $sbOriginal