(Xojo Plugin) 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 Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

// 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.
Dim sbRsaJwk As New Chilkat.StringBuilder
Dim success As Boolean
success = sbRsaJwk.Append("{""kty"":""RSA"",")
success = sbRsaJwk.Append("""n"":""ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx")
success = sbRsaJwk.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
success = sbRsaJwk.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
success = sbRsaJwk.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
success = sbRsaJwk.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
success = sbRsaJwk.Append("NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ"",")
success = sbRsaJwk.Append("""e"":""AQAB""")
success = sbRsaJwk.Append("}")

Dim rsaKey As New Chilkat.PublicKey
Dim success As Boolean
success = rsaKey.LoadFromString(sbRsaJwk.GetAsString())
If (success <> True) Then
    System.DebugLog(rsaKey.LastErrorText)
    Return
End If

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

Dim eccKey As New Chilkat.PublicKey
success = eccKey.LoadFromString(sbEccJwk.GetAsString())
If (success <> True) Then
    System.DebugLog(eccKey.LastErrorText)
    Return
End If

// ---------------------------------------------------
// The HMAC key (in base64url format)
Dim hmacKey As String
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"
//     }
//   ]
// }

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

Dim jws As New Chilkat.Jws

success = jws.LoadJwsSb(sbJws)
If (success <> True) Then
    System.DebugLog(jws.LastErrorText)
    Return
End If

// The payload is easily accessible:
System.DebugLog("Payload: " + jws.GetPayload("utf-8"))

Dim protHeader As Chilkat.JsonObject
Dim sbKeyId As New Chilkat.StringBuilder
Dim bCaseSensitive As Boolean
bCaseSensitive = False

Dim numSignatures As Int32
numSignatures = jws.NumSignatures
Dim i As Int32
i = 0
While i < numSignatures
    protHeader = jws.GetProtectedHeader(i)

    System.DebugLog("--------------------------")
    System.DebugLog(Str(i) + ": ")

    // Get the protected header.
    protHeader.EmitCompact = False
    System.DebugLog(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 
    success = sbKeyId.Append(protHeader.StringOf("kid"))

    // Set the key based on key ID.
    If (sbKeyId.ContentsEqual("myRsaKey",bCaseSensitive) = True) Then
        success = jws.SetPublicKey(i,rsaKey)
    End If

    If (sbKeyId.ContentsEqual("myEcKey",bCaseSensitive) = True) Then
        success = jws.SetPublicKey(i,eccKey)
    End If

    If (sbKeyId.ContentsEqual("myMacKey",bCaseSensitive) = True) Then
        success = jws.SetMacKey(i,hmacKey,"base64url")
    End If

    // Validate this signature.
    Dim v As Int32
    v = jws.Validate(i)
    If (v < 0) Then
        // Perhaps Chilkat was not unlocked or the trial expired..
        System.DebugLog("Validate failed for some other reason.")
        System.DebugLog(jws.LastErrorText)
    Else
        If (v = 0) Then
            System.DebugLog("Invalid signature.  The key was incorrect, the JWS was invalid, or both.")
        Else
            System.DebugLog("Signature validated.")
        End If

    End If

    i = i + 1
Wend

// 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.