(PowerShell) Validate JWS Using HMAC SHA-256

Validates a JSON Web Signature (JWS) using HMAC SHA-256.

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.

# This example takes a JSON signature in compact serialization format,
# and uses a MAC key to validate and recover the protected header and payload.

$jws = New-Object Chilkat.Jws

# Set the HMAC key:
$hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
$signatureIndex = 0
$jws.SetMacKey($signatureIndex,$hmacKey,"base64url")

# Load the JWS.
$jwsCompact = "eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
$success = $jws.LoadJws($jwsCompact)

# Validate the 1st (and only) signature at index 0..
$v = $jws.Validate($signatureIndex)
if ($v -lt 0) {
    # Perhaps Chilkat was not unlocked or the trial expired..
    $("Method call failed for some other reason.")
    $($jws.LastErrorText)
    exit
}

if ($v -eq 0) {
    $("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.")
    exit
}

# If we get here, the signature was validated..
$("Signature validated.")

# Recover the original content:
$("Recovered content:")
$($jws.GetPayload("utf-8"))

# Examine the protected header:
$joseHeader = $jws.GetProtectedHeader($signatureIndex)
if ($jws.LastMethodSuccess -ne $true) {
    $("No protected header found at the given index.")
    exit
}

$joseHeader.EmitCompact = $false

$("Protected (JOSE) header:")
$($joseHeader.Emit())

# Output:

# 	Signature validated.
# 	Recovered content:
# 	{"iss":"joe",
# 	 "exp":1300819380,
# 	 "http://example.com/is_root":true}
# 	Protected (JOSE) header:
# 	{ 
# 	  "typ": "JWT",
# 	  "alg": "HS256"
# 	}