(PowerShell) Validate JWS Using RSASSA-PKCS1-v1_5 SHA-256

Validates a JSON Web Signature (JWS) that uses RSASSA-PKCS1-v1_5 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 an RSA public key to validate and recover the protected header and payload.

# We only need a public key for signature validation.  This is the RSA public key
# that is used:

#      {"kty":"RSA", 
#       "n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
#            HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
#            D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
#            SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
#            MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
#            NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ", 
#       "e":"AQAB"
#      }

$sbPubKey = New-Object Chilkat.StringBuilder
$sbPubKey.Append("{`"kty`":`"RSA`",")
$sbPubKey.Append("`"n`":`"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx")
$sbPubKey.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
$sbPubKey.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
$sbPubKey.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
$sbPubKey.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
$sbPubKey.Append("NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ`",")
$sbPubKey.Append("`"e`":`"AQAB`"")
$sbPubKey.Append("}")

$pubKey = New-Object Chilkat.PublicKey
$success = $pubKey.LoadFromString($sbPubKey.GetAsString())
if ($success -ne $true) {
    $($pubKey.LastErrorText)
    exit
}

$jws = New-Object Chilkat.Jws

# Set the RSA public key:
$signatureIndex = 0
$jws.SetPublicKey($signatureIndex,$pubKey)

# Load the JWS.
$sbJws = New-Object Chilkat.StringBuilder
$sbJws.Append("eyJhbGciOiJSUzI1NiJ9")
$sbJws.Append(".")
$sbJws.Append("eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt")
$sbJws.Append("cGxlLmNvbS9pc19yb290Ijp0cnVlfQ")
$sbJws.Append(".")
$sbJws.Append("cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7")
$sbJws.Append("AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4")
$sbJws.Append("BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K")
$sbJws.Append("0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv")
$sbJws.Append("hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB")
$sbJws.Append("p0igcN_IoypGlUPQGe77Rw")

$success = $jws.LoadJwsSb($sbJws)
if ($success -ne $true) {
    $($jws.LastErrorText)
    exit
}

# 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 RSA 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:
# 	{ 
# 	  "alg": "RS256"
# 	}