Get-Encryption

#description: script to encrypt a string using a certificate then decrypt the string as a POC
#language: powershell
#author: Ben Williamson

$string = "My secret string"
$certThumbprint = "My certificate thumbprint"
$cert = Get-ChildItem -Path "Cert:\LocalMachine\My" | Where-Object {$_.Thumbprint -eq $certThumbprint}

# Get the public key from the certificate
$publicKey = $cert.PublicKey.Key

# Encrypt the string using the public key
$rsa = New-Object System.Security.Cryptography.RSACryptoServiceProvider
$rsa.ImportParameters($publicKey.ExportParameters($false))
$encryptedBytes = $rsa.Encrypt([System.Text.Encoding]::UTF8.GetBytes($string), $true)
$encryptedString = [System.Convert]::ToBase64String($encryptedBytes)

# Decrypt the string using the certificate's private key
$privateKey = $cert.PrivateKey
$rsa = New-Object System.Security.Cryptography.RSACryptoServiceProvider
$rsa.ImportParameters($privateKey.ExportParameters($true))
$decryptedBytes = $rsa.Decrypt([System.Convert]::FromBase64String($encryptedString), $true)
$decryptedString = [System.Text.Encoding]::UTF8.GetString($decryptedBytes)

# Output the original string, encrypted string, and decrypted string
Write-Output "Original String: $string"
Write-Output "Encrypted String: $encryptedString"
Write-Output "Decrypted String: $decryptedString"