(PowerShell) RSA Encrypt and Decrypt Credit Card Numbers

PowerShell sample code to RSA public-key encrypt and decrypt credit card numbers. The RSA key is loaded from an unencrypted PKCS8 file. Chilkat provides many ways of setting the key -- loading from both encrypted and unencrypted PEM, PKCS8, DER, PVK, etc. Keys may be loaded from files or in-memory representations. (The RSA component also provides the ability to generate RSA keys.)

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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.

$rsa = New-Object Chilkat.Rsa

$key = New-Object Chilkat.PrivateKey

# Load an RSA private key from a file:
$success = $key.LoadAnyFormatFile("rsaPrivateKey.key","")
if ($success -ne $true) {
    $($key.LastErrorText)
    exit
}

# Get the key as XML:

$keyXml = $key.GetXml()

# We'll encrypt with the public key and decrypt with the private
# key.  (It's also possible to do the reverse.)
# Note: An RSA private key is composed of different parts internally: modulus, exponent, P, Q, etc.
# An RSA public-key is a sub-set of the private key.
# Therefore, when you have a private key, you really have
# both public and private keys.
$success = $rsa.ImportPublicKey($keyXml)
if ($success -ne $true) {
    $($rsa.LastErrorText)
    exit
}

# Encrypt a VISA credit card number:
# 1234-5678-0000-9999
$ccNumber = "1234567800009999"

$usePrivateKey = $false
$rsa.EncodingMode = "base64"
$encryptedStr = $rsa.EncryptStringENC($ccNumber,$usePrivateKey)
$("Encrypted:")
$($encryptedStr)

# Now decrypt:
$rsaDecryptor = New-Object Chilkat.Rsa

$rsaDecryptor.EncodingMode = "base64"
$success = $rsaDecryptor.ImportPrivateKey($keyXml)

$usePrivateKey = $true
$decryptedStr = $rsaDecryptor.DecryptStringENC($encryptedStr,$usePrivateKey)

$("Decrypted:")
$($decryptedStr)

# Important: RSA encryption should only be used to encrypt small amounts of data.
# It is typically used for encrypting symmetric encryption
# keys such that a symmetric encryption algorithm, such as 
# AES is then used to encrypt/decrypt bulk data