(PowerShell) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

Note: This example requires Chilkat v11.0.0 or greater.

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

$success = $false

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

$privKey = New-Object Chilkat.PrivateKey

# Load the private key from an RSA PEM file:
$success = $privKey.LoadAnyFormatFile("raul_privateKey.key","a0123456789")
if ($success -eq $false) {
    $($privKey.LastErrorText)
    exit
}

$rsa = New-Object Chilkat.Rsa

# Import the private key into the RSA component:
$success = $rsa.UsePrivateKey($privKey)
if ($success -eq $false) {
    $($rsa.LastErrorText)
    exit
}

# This example will sign a string, and receive the signature
# in a hex-encoded string.  Therefore, set the encoding mode
# to "hex":
$rsa.EncodingMode = "hex"

$strData = "This is the string to be signed."

# Sign the string using the sha256 hash algorithm.
# Other valid choices are sha1, sha384, sha512 and others.
$hexSig = $rsa.SignStringENC($strData,"sha256")
if ($rsa.LastMethodSuccess -eq $false) {
    $($rsa.LastErrorText)
    exit
}

$($hexSig)

# Now verify with the public key.
# This example shows how to use the public key from 
# a digital certificate (.cer file)
$cert = New-Object Chilkat.Cert
$success = $cert.LoadFromFile("raul_publicKey.cer")
if ($success -eq $false) {
    $($cert.LastErrorText)
    exit
}

$pubKey = New-Object Chilkat.PublicKey
$cert.GetPublicKey($pubKey)

$rsa2 = New-Object Chilkat.Rsa
$success = $rsa2.UsePublicKey($pubKey)
if ($success -eq $false) {
    $($rsa2.LastErrorText)
    exit
}

# Verify the signature against the original data:
$rsa2.EncodingMode = "hex"
$success = $rsa2.VerifyStringENC($strData,"sha256",$hexSig)
if ($success -eq $false) {
    $($rsa2.LastErrorText)
    exit
}

$("Signature verified!")

# Verify with incorrect data:
$success = $rsa2.VerifyStringENC("something else","sha256",$hexSig)
if ($success -ne $true) {
    $("Signature not verified! (which was expected in this case)")
}
else {
    $("Hmmm... that's not right...")
}