(PowerShell) JWE using PBES2 Key Wrapping

Demonstrates how to create and decrypt a JWE that using PBES2 key wrapping.

This example demonstrates PBES2 with HMAC SHA-256 and A128KW wrapping. It is also possible to do the following by simply changing the "alg" parameter:

• PBES2 with HMAC SHA-384 and A192KW wrapping
• PBES2 with HMAC SHA-512 and A256KW wrapping

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..
$jweProtHdr = New-Object Chilkat.JsonObject
$jweProtHdr.AppendString("alg","PBES2-HS256+A128KW")
$jweProtHdr.AppendString("enc","A128GCM")

# PBES2 requires two additional parameters:
# 1) A random salt parameter ("p2s") containing 8 or more bytes in base64url format.
# 2) An iteration count parameter ("p2c").  A minimum count of 1000 is recommended.
#    The iteration count is intended to make the PBES2 computation more expensive (time consuming)
#    to prevent brute-force attacks.
$prng = New-Object Chilkat.Prng
$jweProtHdr.AppendString("p2s",$prng.GenRandom(16,"base64url"))
$jweProtHdr.AppendString("p2c","1000")

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

# Don't forget to actually provide the protected header to the JWE object:
$jwe.SetProtectedHeader($jweProtHdr)

# Set the PBES2 password
$recipientIndex = 0
$jwe.SetPassword($recipientIndex,"top secret")

# 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.
$jwe2 = New-Object Chilkat.Jwe
$success = $jwe2.LoadJwe($strJwe)
if ($success -ne $true) {
    $($jwe2.LastErrorText)
    exit
}

# Set the PBES2 password
$jwe2.SetPassword($recipientIndex,"top secret")

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

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

# Sample output:

# JWE Protected Header: {"alg":"PBES2-HS256+A128KW","enc":"A128GCM","p2s":"z39rTEfRy1T1Yn_D1mZRlg","p2c":"1000"}
# --
# eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4R0NNIiwicDJzIjoiejM5clRFZlJ5MVQxWW5fRDFtWlJsZyIsInAyYyI6IjEwMDAifQ.koYt6PrFmYwcwdcT7ZcvXHA1d-Xez5h4.luGlbvEnZp-7IsBOj42Yhw.YMTcfLf8Qe4zazozGV2OAu3cUdQ8Kg.rWub47ESWkc6IqZJTvSTmg
# original text: 
# Live long and prosper.