(Tcl) Streaming Encryption

Encrypt and decrypt using a stream.

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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.

set crypt [new_CkCrypt2]

# Setup encryption using the chacha20 algorithm...
CkCrypt2_put_CryptAlgorithm $crypt "chacha20"
CkCrypt2_put_KeyLength $crypt 256
CkCrypt2_put_EncodingMode $crypt "hex"
set ivHex "000000000000000000000002"
CkCrypt2_SetEncodedIV $crypt $ivHex "hex"
CkCrypt2_put_InitialCount $crypt 42
set keyHex "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0"
CkCrypt2_SetEncodedKey $crypt $keyHex "hex"

set plainText "The quick brown fox jumped over the lazy dog.\r\n"

set stream [new_CkStream]

# We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
set eStrings [new_CkStringArray]

# Start a background task that will encrypt a stream.
# task is a CkTask
set task [CkCrypt2_EncryptStreamAsync $crypt $stream]
set success [CkTask_Run $task]

# Write plainText to the stream, and read chacha20 encrypted text..

for {set i 1} {$i <= 10} {incr i} {
    # Note: An encryption algorithm's block size will cause buffering,
    # and therefore not every loop iteration will produce output.
    set success [CkStream_WriteString $stream $plainText]
    if {[CkStream_get_DataAvailable $stream] == 1} then {
        set cipherText [CkStream_readBytesENC $stream "hex"]
        puts "$cipherText"
        set success [CkStringArray_Append $eStrings $cipherText]
    }

}

# Tell the background task that the stream has ended.
set success [CkStream_WriteClose $stream]

# Let's make sure the background task finished.
# It should already be the case that the task is finished.
while {[CkTask_get_Finished $task] != 1} {
    CkTask_SleepMs $task 20
}

# Get any remaining data available from the stream.
if {[CkStream_get_DataAvailable $stream] == 1} then {
    set cipherText [CkStream_readBytesENC $stream "hex"]
    puts "$cipherText"
    set success [CkStringArray_Append $eStrings $cipherText]
}

if {[CkTask_get_TaskSuccess $task] != 1} then {
    puts "async encryption failed:"
    puts [CkTask_resultErrorText $task]
    set success 0
}

delete_CkTask $task

puts "-- encrypt finished --"

# Now decrypt to return the original.

# Reset the stream object so it can be used again.
CkStream_Reset $stream

# Start a background task that will decrypt a stream.
set task [CkCrypt2_DecryptStreamAsync $crypt $stream]
set success [CkTask_Run $task]

set n [CkStringArray_get_Count $eStrings]
for {set i 0} {$i <= [expr $n - 1]} {incr i} {
    set success [CkStream_WriteBytesENC $stream [CkStringArray_getString $eStrings $i] "hex"]
    if {[CkStream_get_DataAvailable $stream] == 1} then {
        set plainText [CkStream_readString $stream]
        puts "$plainText"
    }

}

# Tell the background task that the stream has ended.
set success [CkStream_WriteClose $stream]

# Let's make sure the background task finished.
# It should already be the case that the task is finished.
while {[CkTask_get_Finished $task] != 1} {
    CkTask_SleepMs $task 20
}

# Get any remaining data available from the stream.
if {[CkStream_get_DataAvailable $stream] == 1} then {
    set plainText [CkStream_readString $stream]
    puts "$plainText"
}

if {[CkTask_get_TaskSuccess $task] != 1} then {
    puts "async decryption failed:"
    puts [CkTask_resultErrorText $task]
    set success 0
}

delete_CkTask $task

puts "-- decrypt finished --"

delete_CkCrypt2 $crypt
delete_CkStream $stream
delete_CkStringArray $eStrings