(PowerShell) Demonstrate RSA Encrypt/Decrypt using BinData

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Demonstrates how to RSA encrypt and decrypt data contained in a Chilkat BinData object.

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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

# Create some binary data to encrypt.
$bd = New-Object Chilkat.BinData
$i = 0
for ($i = 0; $i -le 49; $i++) {
    $bd.AppendByte($i)
}

# Show the bytes to be encrypted in hex format:
$("To be encrypted: " + $bd.GetEncoded("hex"))

# To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

# RSA encrypt the contents of the bd, replacing the contents with the RSA encrypted data.
$rsa.EncryptBd($bd,$false)

# Now it is encrypted.
$("Encrypted size = " + $bd.NumBytes)
$($bd.GetEncoded("hex"))

# Encrypted size = 256
# 749ED9D0A8767C06C09AD9697F654F86B145F966722F9714902C4175BDBD02E68984ECF111D4D461
# EDB4A8E677D399D19CCA60F35C6DE9972F4262880FE9D77DB75915393E8E7DB80AAB5E383013FAEB
# 60C77D1E6FECC9A7C8426976416C6218FE7DA998EE063CE709E79C240F8625F4A56A0A33AFD63F7A
# BA26F2A692B42E878C53B78602C725FE63FF961A46A2B9D436E5E3D9D64AE3F1D1F5AD5F5B47FCD69
# 447306B77F2FD6D766CCAA1A110A3371586B43DF0D7FFE2220D1B305CF9371AC342F849FB0C90CD99E
# C176928D877FE1C0DE1A7CB6EB824FEC7E1DCF90EF2C6BA9F1DFD3EBFBE89C51AF074DC6AE02E544A78
# 5018C36D3D48B2EF5202AF61AC

# ------------------------------------------------------------------------------------------------------------------------
# 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)

# Decrypt
$success = $rsa.DecryptBd($bd,$true)
if ($success -eq $false) {
    $($rsa.LastErrorText)
    exit
}

# Examine the contents of bd to see if it now contains the unencrypted original data.
$("Decrypted: " + $bd.GetEncoded("hex"))

# Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031