(Lianja) 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 Lianja Extension Download Chilkat Lianja Extension

// 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.
loSbRsaJwk = createobject("CkStringBuilder")
loSbRsaJwk.Append('{"kty":"RSA",')
loSbRsaJwk.Append('"n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx')
loSbRsaJwk.Append("HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
loSbRsaJwk.Append("D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
loSbRsaJwk.Append("SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
loSbRsaJwk.Append("MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
loSbRsaJwk.Append('NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ",')
loSbRsaJwk.Append('"e":"AQAB"')
loSbRsaJwk.Append("}")

loRsaKey = createobject("CkPublicKey")
llSuccess = loRsaKey.LoadFromString(loSbRsaJwk.GetAsString())
if (llSuccess <> .T.) then
    ? loRsaKey.LastErrorText
    release loSbRsaJwk
    release loRsaKey
    return
endif

// ---------------------------------------------------
// Use the following ECC public key loaded from JWK format.
loSbEccJwk = createobject("CkStringBuilder")
loSbEccJwk.Append('{"kty":"EC",')
loSbEccJwk.Append('"crv":"P-256",')
loSbEccJwk.Append('"x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",')
loSbEccJwk.Append('"y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0"')
loSbEccJwk.Append("}")

loEccKey = createobject("CkPublicKey")
llSuccess = loEccKey.LoadFromString(loSbEccJwk.GetAsString())
if (llSuccess <> .T.) then
    ? loEccKey.LastErrorText
    release loSbRsaJwk
    release loRsaKey
    release loSbEccJwk
    release loEccKey
    return
endif

// ---------------------------------------------------
// The HMAC key (in base64url format)
lcHmacKey = "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"
//     }
//   ]
// }

loSbJws = createobject("CkStringBuilder")
loSbJws.Append("{ ")
loSbJws.Append('  "payload": "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu",')
loSbJws.Append('  "signatures": [')
loSbJws.Append("    { ")
loSbJws.Append('      "protected": "eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0",')
loSbJws.Append('      "signature": "IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw"')
loSbJws.Append("    },")
loSbJws.Append("    { ")
loSbJws.Append('      "protected": "eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ",')
loSbJws.Append('      "signature": "1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw"')
loSbJws.Append("    },")
loSbJws.Append("    { ")
loSbJws.Append('      "protected": "eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0",')
loSbJws.Append('      "signature": "YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw"')
loSbJws.Append("    }")
loSbJws.Append("  ]")
loSbJws.Append("}")

loJws = createobject("CkJws")

llSuccess = loJws.LoadJwsSb(loSbJws)
if (llSuccess <> .T.) then
    ? loJws.LastErrorText
    release loSbRsaJwk
    release loRsaKey
    release loSbEccJwk
    release loEccKey
    release loSbJws
    release loJws
    return
endif

// The payload is easily accessible:
? "Payload: " + loJws.GetPayload("utf-8")

loSbKeyId = createobject("CkStringBuilder")
llBCaseSensitive = .F.

lnNumSignatures = loJws.NumSignatures
i = 0
do while i < lnNumSignatures
    loProtHeader = loJws.GetProtectedHeader(i)

    ? "--------------------------"
    ? str(i) + ": "

    // Get the protected header.
    loProtHeader.EmitCompact = .F.
    ? loProtHeader.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).

    loSbKeyId.Clear()
    loSbKeyId.Append(loProtHeader.StringOf("kid"))

    // Set the key based on key ID.
    if (loSbKeyId.ContentsEqual("myRsaKey",llBCaseSensitive) = .T.) then
        loJws.SetPublicKey(i,loRsaKey)
    endif

    if (loSbKeyId.ContentsEqual("myEcKey",llBCaseSensitive) = .T.) then
        loJws.SetPublicKey(i,loEccKey)
    endif

    if (loSbKeyId.ContentsEqual("myMacKey",llBCaseSensitive) = .T.) then
        loJws.SetMacKey(i,lcHmacKey,"base64url")
    endif

    // Validate this signature.
    v = loJws.Validate(i)
    if (v < 0) then
        // Perhaps Chilkat was not unlocked or the trial expired..
        ? "Validate failed for some other reason."
        ? loJws.LastErrorText
    else
        if (v = 0) then
            ? "Invalid signature.  The key was incorrect, the JWS was invalid, or both."
        else
            ? "Signature validated."
        endif

    endif

    release loProtHeader
    i = i + 1
enddo

// 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.


release loSbRsaJwk
release loRsaKey
release loSbEccJwk
release loEccKey
release loSbJws
release loJws
release loSbKeyId