(PowerShell) Validate JWS with Multiple Signatures using the General JSON Serialization Format

Validates and recovers data and headers from a JSON Web Signature (JWS) containing 3 signatures.

Note: Chilkat supports all of the following JWS algorithms:

   +--------------+-------------------------------+--------------------+
   | "alg" Param  | Digital Signature or MAC      | Implementation     |
   | Value        | Algorithm                     | Requirements       |
   +--------------+-------------------------------+--------------------+
   | HS256        | HMAC using SHA-256            | Required           |
   | HS384        | HMAC using SHA-384            | Optional           |
   | HS512        | HMAC using SHA-512            | Optional           |
   | RS256        | RSASSA-PKCS1-v1_5 using       | Recommended        |
   |              | SHA-256                       |                    |
   | RS384        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-384                       |                    |
   | RS512        | RSASSA-PKCS1-v1_5 using       | Optional           |
   |              | SHA-512                       |                    |
   | ES256        | ECDSA using P-256 and SHA-256 | Recommended+       |
   | ES384        | ECDSA using P-384 and SHA-384 | Optional           |
   | ES512        | ECDSA using P-521 and SHA-512 | Optional           |
   | PS256        | RSASSA-PSS using SHA-256 and  | Optional           |
   |              | MGF1 with SHA-256             |                    |
   | PS384        | RSASSA-PSS using SHA-384 and  | Optional           |
   |              | MGF1 with SHA-384             |                    |
   | PS512        | RSASSA-PSS using SHA-512 and  | Optional           |
   |              | MGF1 with SHA-512             |                    |
   +--------------+-------------------------------+--------------------+

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.

# First, prepare the public keys that will be needed for each signature.

# ---------------------------------------------------
# Use the following RSA key loaded from JWK format.
$sbRsaJwk = New-Object Chilkat.StringBuilder
$sbRsaJwk.Append("{`"kty`":`"RSA`",")
$sbRsaJwk.Append("`"n`":`"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx")
$sbRsaJwk.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
$sbRsaJwk.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
$sbRsaJwk.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
$sbRsaJwk.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
$sbRsaJwk.Append("NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ`",")
$sbRsaJwk.Append("`"e`":`"AQAB`"")
$sbRsaJwk.Append("}")

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

# ---------------------------------------------------
# Use the following ECC public key loaded from JWK format.
$sbEccJwk = New-Object Chilkat.StringBuilder
$sbEccJwk.Append("{`"kty`":`"EC`",")
$sbEccJwk.Append("`"crv`":`"P-256`",")
$sbEccJwk.Append("`"x`":`"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU`",")
$sbEccJwk.Append("`"y`":`"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0`"")
$sbEccJwk.Append("}")

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

# ---------------------------------------------------
# The HMAC key (in base64url format)
$hmacKey = "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"

# The code below will verify each of the signatures in this JWS:

# { 
#   "payload": "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu",
#   "signatures": [
#     { 
#       "protected": "eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0",
#       "signature": "IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw"
#     },
#     { 
#       "protected": "eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ",
#       "signature": "1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw"
#     },
#     { 
#       "protected": "eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0",
#       "signature": "YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw"
#     }
#   ]
# }

$sbJws = New-Object Chilkat.StringBuilder
$sbJws.Append("{ ")
$sbJws.Append("  `"payload`": `"SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu`",")
$sbJws.Append("  `"signatures`": [")
$sbJws.Append("    { ")
$sbJws.Append("      `"protected`": `"eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0`",")
$sbJws.Append("      `"signature`": `"IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw`"")
$sbJws.Append("    },")
$sbJws.Append("    { ")
$sbJws.Append("      `"protected`": `"eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ`",")
$sbJws.Append("      `"signature`": `"1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw`"")
$sbJws.Append("    },")
$sbJws.Append("    { ")
$sbJws.Append("      `"protected`": `"eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0`",")
$sbJws.Append("      `"signature`": `"YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw`"")
$sbJws.Append("    }")
$sbJws.Append("  ]")
$sbJws.Append("}")

$jws = New-Object Chilkat.Jws

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

# The payload is easily accessible:
$("Payload: " + $jws.GetPayload("utf-8"))

$sbKeyId = New-Object Chilkat.StringBuilder
$bCaseSensitive = $false

$numSignatures = $jws.NumSignatures
$i = 0
while ($i -lt $numSignatures) {
    $protHeader = $jws.GetProtectedHeader($i)

    $("--------------------------")
    $([string]$i + ": ")

    # Get the protected header.
    $protHeader.EmitCompact = $false
    $($protHeader.Emit())

    # Get the key ID ("kid") member.

    # Note: In this example, the "kid" values are contained in the protected headers.
    # They could've just as easily been located in unprotected headers.  In that case,
    # we would've called GetUnprotectedHeader(i) instead of GetProtectedHeader(i).

    $sbKeyId.Clear()
    $sbKeyId.Append($protHeader.StringOf("kid"))

    # Set the key based on key ID.
    if ($sbKeyId.ContentsEqual("myRsaKey",$bCaseSensitive) -eq $true) {
        $jws.SetPublicKey($i,$rsaKey)
    }

    if ($sbKeyId.ContentsEqual("myEcKey",$bCaseSensitive) -eq $true) {
        $jws.SetPublicKey($i,$eccKey)
    }

    if ($sbKeyId.ContentsEqual("myMacKey",$bCaseSensitive) -eq $true) {
        $jws.SetMacKey($i,$hmacKey,"base64url")
    }

    # Validate this signature.
    $v = $jws.Validate($i)
    if ($v -lt 0) {
        # Perhaps Chilkat was not unlocked or the trial expired..
        $("Validate failed for some other reason.")
        $($jws.LastErrorText)
    }
    else {
        if ($v -eq 0) {
            $("Invalid signature.  The key was incorrect, the JWS was invalid, or both.")
        }
        else {
            $("Signature validated.")
        }

    }

    $i = $i + 1
}

# The output of this program is:

# 	Payload: In our village, folks say God crumbles up the old moon into stars.
# 	--------------------------
# 	0: 
# 	{
# 	  "alg": "RS256",
# 	  "kid": "myRsaKey"
# 	}
# 
# 	Signature validated.
# 	--------------------------
# 	1: 
# 	{
# 	  "alg": "ES256",
# 	  "kid": "myEcKey"
# 	}
# 
# 	Signature validated.
# 	--------------------------
# 	2: 
# 	{
# 	  "alg": "HS256",
# 	  "kid": "myMacKey"
# 	}
# 
# 	Signature validated.