(PowerShell) Streaming Encryption

Encrypt and decrypt using a stream.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

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

$crypt = New-Object Chilkat.Crypt2

# Setup encryption using the chacha20 algorithm...
$crypt.CryptAlgorithm = "chacha20"
$crypt.KeyLength = 256
$crypt.EncodingMode = "hex"
$ivHex = "000000000000000000000002"
$crypt.SetEncodedIV($ivHex,"hex")
$crypt.InitialCount = 42
$keyHex = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0"
$crypt.SetEncodedKey($keyHex,"hex")

$plainText = "The quick brown fox jumped over the lazy dog.`r`n"

$stream = New-Object Chilkat.Stream

# We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
$eStrings = New-Object Chilkat.StringArray

# Start a background task that will encrypt a stream.
$task = $crypt.EncryptStreamAsync($stream)
$success = $task.Run()

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

for ($i = 1; $i -le 10; $i++) {
    # Note: An encryption algorithm's block size will cause buffering,
    # and therefore not every loop iteration will produce output.
    $success = $stream.WriteString($plainText)
    if ($stream.DataAvailable -eq $true) {
        $cipherText = $stream.ReadBytesENC("hex")
        $($cipherText)
        $success = $eStrings.Append($cipherText)
    }

}

# Tell the background task that the stream has ended.
$success = $stream.WriteClose()

# Let's make sure the background task finished.
# It should already be the case that the task is finished.
while (($task.Finished -ne $true)) {
    $task.SleepMs(20)
}

# Get any remaining data available from the stream.
if ($stream.DataAvailable -eq $true) {
    $cipherText = $stream.ReadBytesENC("hex")
    $($cipherText)
    $success = $eStrings.Append($cipherText)
}

if ($task.TaskSuccess -ne $true) {
    $("async encryption failed:")
    $($task.ResultErrorText)
    $success = $false
}

$("-- encrypt finished --")

# Now decrypt to return the original.

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

# Start a background task that will decrypt a stream.
$task = $crypt.DecryptStreamAsync($stream)
$success = $task.Run()

$n = $eStrings.Count
for ($i = 0; $i -le $n - 1; $i++) {
    $success = $stream.WriteBytesENC($eStrings.GetString($i),"hex")
    if ($stream.DataAvailable -eq $true) {
        $plainText = $stream.ReadString()
        $($plainText)
    }

}

# Tell the background task that the stream has ended.
$success = $stream.WriteClose()

# Let's make sure the background task finished.
# It should already be the case that the task is finished.
while (($task.Finished -ne $true)) {
    $task.SleepMs(20)
}

# Get any remaining data available from the stream.
if ($stream.DataAvailable -eq $true) {
    $plainText = $stream.ReadString()
    $($plainText)
}

if ($task.TaskSuccess -ne $true) {
    $("async decryption failed:")
    $($task.ResultErrorText)
    $success = $false
}

$("-- decrypt finished --")