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PureBasic

Validate JWS with Multiple Signatures using the General JSON Serialization Format

See more JSON Web Signatures (JWS) Examples

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             |                    |
   +--------------+-------------------------------+--------------------+

Chilkat PureBasic Downloads

PureBasic
IncludeFile "CkJws.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkPublicKey.pb"

Procedure ChilkatExample()

    success.i = 0

    ; This requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

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

    ; ---------------------------------------------------
    ; Use the following RSA key loaded from JWK format.
    sbRsaJwk.i = CkStringBuilder::ckCreate()
    If sbRsaJwk.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbRsaJwk,"{" + Chr(34) + "kty" + Chr(34) + ":" + Chr(34) + "RSA" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbRsaJwk,Chr(34) + "n" + Chr(34) + ":" + Chr(34) + "ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx")
    CkStringBuilder::ckAppend(sbRsaJwk,"HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs")
    CkStringBuilder::ckAppend(sbRsaJwk,"D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH")
    CkStringBuilder::ckAppend(sbRsaJwk,"SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV")
    CkStringBuilder::ckAppend(sbRsaJwk,"MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8")
    CkStringBuilder::ckAppend(sbRsaJwk,"NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbRsaJwk,Chr(34) + "e" + Chr(34) + ":" + Chr(34) + "AQAB" + Chr(34))
    CkStringBuilder::ckAppend(sbRsaJwk,"}")

    rsaKey.i = CkPublicKey::ckCreate()
    If rsaKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPublicKey::ckLoadFromString(rsaKey,CkStringBuilder::ckGetAsString(sbRsaJwk))
    If success = 0
        Debug CkPublicKey::ckLastErrorText(rsaKey)
        CkStringBuilder::ckDispose(sbRsaJwk)
        CkPublicKey::ckDispose(rsaKey)
        ProcedureReturn
    EndIf

    ; ---------------------------------------------------
    ; Use the following ECC public key loaded from JWK format.
    sbEccJwk.i = CkStringBuilder::ckCreate()
    If sbEccJwk.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbEccJwk,"{" + Chr(34) + "kty" + Chr(34) + ":" + Chr(34) + "EC" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbEccJwk,Chr(34) + "crv" + Chr(34) + ":" + Chr(34) + "P-256" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbEccJwk,Chr(34) + "x" + Chr(34) + ":" + Chr(34) + "f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbEccJwk,Chr(34) + "y" + Chr(34) + ":" + Chr(34) + "x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0" + Chr(34))
    CkStringBuilder::ckAppend(sbEccJwk,"}")

    eccKey.i = CkPublicKey::ckCreate()
    If eccKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPublicKey::ckLoadFromString(eccKey,CkStringBuilder::ckGetAsString(sbEccJwk))
    If success = 0
        Debug CkPublicKey::ckLastErrorText(eccKey)
        CkStringBuilder::ckDispose(sbRsaJwk)
        CkPublicKey::ckDispose(rsaKey)
        CkStringBuilder::ckDispose(sbEccJwk)
        CkPublicKey::ckDispose(eccKey)
        ProcedureReturn
    EndIf

    ; ---------------------------------------------------
    ; The HMAC key (in base64url format)
    hmacKey.s = "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.i = CkStringBuilder::ckCreate()
    If sbJws.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbJws,"{ ")
    CkStringBuilder::ckAppend(sbJws,"  " + Chr(34) + "payload" + Chr(34) + ": " + Chr(34) + "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJws,"  " + Chr(34) + "signatures" + Chr(34) + ": [")
    CkStringBuilder::ckAppend(sbJws,"    { ")
    CkStringBuilder::ckAppend(sbJws,"      " + Chr(34) + "protected" + Chr(34) + ": " + Chr(34) + "eyJhbGciOiJSUzI1NiIsImtpZCI6Im15UnNhS2V5In0" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJws,"      " + Chr(34) + "signature" + Chr(34) + ": " + Chr(34) + "IPMQ02niTQDwLzsRZSCaEm9VEyAX_AVe3HWjniNt9kW-a8d6ZVbd2k6jGae8s1yIh0cgxDnXQ6-p6_sBI0cnMO0xpuJANhh2vFtNJl5lisad94-H3mB3lSfafRqxeYp5D8bh39BPv7y3PrUNVMQdKEJp_D5oJ0ROPTIYx3EG8eJQOx1HO0KqhcUo401XR6KSsIyFm5joBLNKTVzxZUTT1RRZZtwTdeZkbGevugIOX_9gHAtARpV6WaFA4Vvjnq8X9wPgqjWNCQRupadhTPz0JAsa-wy5vXQjsFlXAn43mDPpMfna5Ab3F5pS4yDwkbX6nRn7XBxH1SnnNJRFholQZw" + Chr(34))
    CkStringBuilder::ckAppend(sbJws,"    },")
    CkStringBuilder::ckAppend(sbJws,"    { ")
    CkStringBuilder::ckAppend(sbJws,"      " + Chr(34) + "protected" + Chr(34) + ": " + Chr(34) + "eyJhbGciOiJFUzI1NiIsImtpZCI6Im15RWNLZXkifQ" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJws,"      " + Chr(34) + "signature" + Chr(34) + ": " + Chr(34) + "1OQtaT3pgZmkDxvlfghvxL_8kX16WIen6u1MadEq1pA4qytA0--_EwZDNk00GDPWFpoJtKznibMZzLOg_UhHIw" + Chr(34))
    CkStringBuilder::ckAppend(sbJws,"    },")
    CkStringBuilder::ckAppend(sbJws,"    { ")
    CkStringBuilder::ckAppend(sbJws,"      " + Chr(34) + "protected" + Chr(34) + ": " + Chr(34) + "eyJhbGciOiJIUzI1NiIsImtpZCI6Im15TWFjS2V5In0" + Chr(34) + ",")
    CkStringBuilder::ckAppend(sbJws,"      " + Chr(34) + "signature" + Chr(34) + ": " + Chr(34) + "YY8yVjmJJfy7YJOn3uUydG8WCY2PEuCvOLil5Ks5lnw" + Chr(34))
    CkStringBuilder::ckAppend(sbJws,"    }")
    CkStringBuilder::ckAppend(sbJws,"  ]")
    CkStringBuilder::ckAppend(sbJws,"}")

    jws.i = CkJws::ckCreate()
    If jws.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJws::ckLoadJwsSb(jws,sbJws)
    If success = 0
        Debug CkJws::ckLastErrorText(jws)
        CkStringBuilder::ckDispose(sbRsaJwk)
        CkPublicKey::ckDispose(rsaKey)
        CkStringBuilder::ckDispose(sbEccJwk)
        CkPublicKey::ckDispose(eccKey)
        CkStringBuilder::ckDispose(sbJws)
        CkJws::ckDispose(jws)
        ProcedureReturn
    EndIf

    ; The payload is easily accessible:
    Debug "Payload: " + CkJws::ckGetPayload(jws,"utf-8")

    sbKeyId.i = CkStringBuilder::ckCreate()
    If sbKeyId.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    bCaseSensitive.i = 0

    protHeader.i = CkJsonObject::ckCreate()
    If protHeader.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    numSignatures.i = CkJws::ckNumSignatures(jws)
    i.i = 0
    While i < numSignatures
        success = CkJws::ckGetProtectedH(jws,i,protHeader)
        If success = 0
            Debug CkJws::ckLastErrorText(jws)
            CkStringBuilder::ckDispose(sbRsaJwk)
            CkPublicKey::ckDispose(rsaKey)
            CkStringBuilder::ckDispose(sbEccJwk)
            CkPublicKey::ckDispose(eccKey)
            CkStringBuilder::ckDispose(sbJws)
            CkJws::ckDispose(jws)
            CkStringBuilder::ckDispose(sbKeyId)
            CkJsonObject::ckDispose(protHeader)
            ProcedureReturn
        EndIf

        Debug "--------------------------"
        Debug Str(i) + ": "

        ; Get the protected header.
        CkJsonObject::setCkEmitCompact(protHeader, 0)
        Debug CkJsonObject::ckEmit(protHeader)

        ; 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 GetUnprotectedH instead of GetProtectedH(i).

        CkStringBuilder::ckClear(sbKeyId)
        CkStringBuilder::ckAppend(sbKeyId,CkJsonObject::ckStringOf(protHeader,"kid"))

        ; Set the key based on key ID.
        If CkStringBuilder::ckContentsEqual(sbKeyId,"myRsaKey",bCaseSensitive) = 1
            CkJws::ckSetPublicKey(jws,i,rsaKey)
        EndIf

        If CkStringBuilder::ckContentsEqual(sbKeyId,"myEcKey",bCaseSensitive) = 1
            CkJws::ckSetPublicKey(jws,i,eccKey)
        EndIf

        If CkStringBuilder::ckContentsEqual(sbKeyId,"myMacKey",bCaseSensitive) = 1
            CkJws::ckSetMacKey(jws,i,hmacKey,"base64url")
        EndIf

        ; Validate this signature.
        v.i = CkJws::ckValidate(jws,i)
        If v < 0
            ; Perhaps Chilkat was not unlocked or the trial expired..
            Debug "Validate failed for some other reason."
            Debug CkJws::ckLastErrorText(jws)
        Else
            If v = 0
                Debug "Invalid signature.  The key was incorrect, the JWS was invalid, or both."
            Else
                Debug "Signature validated."
            EndIf

        EndIf

        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.


    CkStringBuilder::ckDispose(sbRsaJwk)
    CkPublicKey::ckDispose(rsaKey)
    CkStringBuilder::ckDispose(sbEccJwk)
    CkPublicKey::ckDispose(eccKey)
    CkStringBuilder::ckDispose(sbJws)
    CkJws::ckDispose(jws)
    CkStringBuilder::ckDispose(sbKeyId)
    CkJsonObject::ckDispose(protHeader)


    ProcedureReturn
EndProcedure