(PowerShell) RSA Encrypt String to Encoded Result and Reverse

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Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse.

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

# The RSA public key is used for encryption, and the private key for decryption.

# The public key's role is to make encryption accessible to anyone while ensuring that
# only the private key holder can decrypt the messages.
# The public key is designed to be widely distributed so anyone can use it to encrypt messages
# intended for the owner of the private key.

# Load our 2048-bit RSA public key.
$pubKey = New-Object Chilkat.PublicKey
# In all Chilkat methods expecting a path, you pass either absolute or relative paths.
$success = $pubKey.LoadFromFile("rsaKeys/myTestRsaPublic.pem")
if ($success -eq $false) {
    $($pubKey.LastErrorText)
    exit
}

$rsa = New-Object Chilkat.Rsa

# Tell RSA to use the public key.
$rsa.ImportPublicKeyObj($pubKey)

# RSA encryption is for small amounts of data, on the order of 200 bytes or less.
# The maximum number of bytes that can be RSA encrypted depends
# on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
# For specific limits, see: RSA Encryption Maximum Number of Bytes

# Encrypt the utf-8 byte representation of the string.
$rsa.Charset = "utf-8"
$rsa.EncodingMode = "base64"

# Be Careful when Using non-us-ascii String Literals in Source Code
$encryptedB64 = $rsa.EncryptStringENC("Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux",$false)

# ------------------------------------------------------------------------------------------------------------------------
# Let's decrypt, which requires the matching private key...

# Load the matching 2048-bit RSA private key.
$privKey = New-Object Chilkat.PrivateKey
$password = "secret"
$success = $privKey.LoadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem",$password)
if ($success -eq $false) {
    $($privKey.LastErrorText)
    exit
}

# Tell the RSA object to use the private key.
$rsa.ImportPrivateKeyObj($privKey)

# Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
$rsa.Charset = "utf-8"
$rsa.EncodingMode = "base64"
$originalText = $rsa.DecryptStringENC($encryptedB64,$true)
if ($success -eq $false) {
    $($rsa.LastErrorText)
    exit
}

$("Original text = " + $originalText)
$("Success.")