(PowerShell) JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

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

# Note: This example requires Chilkat v9.5.0.66 or greater.

$plaintext = "Live long and prosper."

$jwe = New-Object Chilkat.Jwe

# First build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256"}
$jweProtHdr = New-Object Chilkat.JsonObject
$jweProtHdr.AppendString("alg","A128KW")
$jweProtHdr.AppendString("enc","A128CBC-HS256")
$jwe.SetProtectedHeader($jweProtHdr)

$("JWE Protected Header: " + $jweProtHdr.Emit())
$("--")

# The example A.3 in RFC 7516 uses the following 128-bit AES key,
# specified in JWK (JSON Web Key) format:
#      {"kty":"oct",
#       "k":"GawgguFyGrWKav7AX4VKUg"
#      }
# This is just a way of saying: The key type ("kty") is 
# a bunch of octets ("k") in base64url encoding.
# We can simply set the AES wrapping key like this:
$aesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
$jwe.SetWrappingKey(0,$aesWrappingKey,"base64url")

# Encrypt and return the JWE:
$strJwe = $jwe.Encrypt($plaintext,"utf-8")
if ($jwe.LastMethodSuccess -ne $true) {
    $($jwe.LastErrorText)
    exit
}

# Show the JWE we just created:
$($strJwe)

# Decrypt the JWE that was just produced.
# 1) Load the JWE.
# 2) Set the AES wrapping key.
# 3) Decrypt.
$jwe2 = New-Object Chilkat.Jwe
$success = $jwe2.LoadJwe($strJwe)
if ($success -ne $true) {
    $($jwe2.LastErrorText)
    exit
}

# Set the AES wrap key.
$jwe2.SetWrappingKey(0,$aesWrappingKey,"base64url")

# Decrypt.
$originalPlaintext = $jwe2.Decrypt(0,"utf-8")
if ($jwe2.LastMethodSuccess -ne $true) {
    $($jwe2.LastErrorText)
    exit
}

$("original text: ")
$($originalPlaintext)

# ---------------------------------------------------------------------------------
# It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
# because it was produced using the same AES Wrap key.

$sbJwe = New-Object Chilkat.StringBuilder
$sbJwe.Append("eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.")
$sbJwe.Append("6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.")
$sbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.")
$sbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.")
$sbJwe.Append("U0m_YmjN04DJvceFICbCVQ")

$success = $jwe2.LoadJweSb($sbJwe)
if ($success -ne $true) {
    $($jwe2.LastErrorText)
    exit
}

$jwe2.SetWrappingKey(0,$aesWrappingKey,"base64url")

# Decrypt.
$originalPlaintext = $jwe2.Decrypt(0,"utf-8")
if ($jwe2.LastMethodSuccess -ne $true) {
    $($jwe2.LastErrorText)
    exit
}

$($originalPlaintext)