(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).

Chilkat .NET Downloads Chilkat .NET Assemblies

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.

$pkey = New-Object Chilkat.PrivateKey

# Load the private key from an RSA PEM file:
$success = $pkey.LoadPkcs8EncryptedFile("raul_privateKey.key","a0123456789")

# Get the private key in XML format:
$pkeyXml = $pkey.GetXml()

$rsa = New-Object Chilkat.Rsa

# Import the private key into the RSA component:
$success = $rsa.ImportPrivateKey($pkeyXml)
if ($success -ne $true) {
    $($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 sha-1 hash algorithm.
# Other valid choices are "md2" and "md5".
$hexSig = $rsa.SignStringENC($strData,"sha-1")

$($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 -ne $true) {
    $($cert.LastErrorText)
    exit
}

$pubKey = $cert.ExportPublicKey()

# Get the private key in XML format:
$pubKeyXml = $pubKey.GetXml()

$rsa2 = New-Object Chilkat.Rsa
$success = $rsa2.ImportPublicKey($pubKeyXml)
if ($success -ne $true) {
    $($rsa2.LastErrorText)
    exit
}

# Verify the signature against the original data:
$rsa2.EncodingMode = "hex"
$success = $rsa2.VerifyStringENC($strData,"sha-1",$hexSig)
if ($success -ne $true) {
    $($rsa2.LastErrorText)
    exit
}

$("Signature verified!")

# Verify with incorrect data:
$success = $rsa2.VerifyStringENC("something else","sha-1",$hexSig)
if ($success -ne $true) {
    $("Signature not verified! (which was expected in this case)")
}
else {
    $("Hmmm... that's not right...")
}