Xbase++ Requires Chilkat v11.0.0+

Validate a Google ID Token

See more OAuth2 Examples

Demonstrates how to verify the signature of a Google id token. Xbase++

LOCAL nSuccess
LOCAL oHttp
LOCAL cJwkStr
LOCAL oJson
LOCAL oJsonToken
LOCAL oSbIdToken
LOCAL cSig_b64Url
LOCAL cHeaderPlusPayload
LOCAL oRsa
LOCAL oJsonKey
LOCAL oPubKey
LOCAL nNumKeys
LOCAL i
LOCAL nBVerified

nSuccess := 0

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

oHttp := CreateObject("Chilkat.Http")

//  First get the public key we'll be needing..
cJwkStr := oHttp:QuickGetStr("https://www.googleapis.com/oauth2/v3/certs")
IF (oHttp:LastMethodSuccess == 0)
    ? oHttp:LastErrorText
    oHttp:destroy()
    RETURN
ENDIF

//  We have the following:

//      {
//        "keys": [
//  	{
//  	  "kid": "e8732db06287515556213b80acbcfd08cfb302a9",
//  	  "n": "4RIrO30287Wsq3gqXCMkUYMVAeI3H8...w2mbMNEBQ",
//  	  "kty": "RSA",
//  	  "e": "AQAB",
//  	  "alg": "RS256",
//  	  "use": "sig"
//  	},
//  	{
//  	  "kid": "8462a71da4f6d611fc0fecf0fc4ba9c37d65e6cd",
//  	  "e": "AQAB",
//  	  "n": "xT_ngLZNmT5GBtJZeTB...Ft4gK0eoFi0d3l8bcw",
//  	  "alg": "RS256",
//  	  "use": "sig",
//  	  "kty": "RSA"
//  	}
//        ]
//      }

oJson := CreateObject("Chilkat.JsonObject")
nSuccess := oJson:Load(cJwkStr)

//  -------------------------------------------------

//  Load the following..

//   {
//    "access_token": "ya29.a0...0f",
//    "expires_in": 3599,
//    "scope": "openid https://www.googleapis.com/auth/userinfo.email",
//    "token_type": "Bearer",
//    "id_token": "eyJhb...o5nQ"
//  }

oJsonToken := CreateObject("Chilkat.JsonObject")
nSuccess := oJsonToken:LoadFile("qa_data/tokens/google_sample_id_token.json")
IF (nSuccess == 0)
    ? "Failed to load the JSON file..."
    oHttp:destroy()
    oJson:destroy()
    oJsonToken:destroy()
    RETURN
ENDIF

//  Get the id_token;
oSbIdToken := CreateObject("Chilkat.StringBuilder")
nSuccess := oSbIdToken:Append(oJsonToken:StringOf("id_token"))

//  Get the signature in base64url format.
//  The header + payload remains in sbIdToken.
cSig_b64Url := oSbIdToken:GetAfterFinal(".", 1)
cHeaderPlusPayload := oSbIdToken:GetAsString()

? cSig_b64Url
? cHeaderPlusPayload

//  ---------------------------------------------

//  Try validating with each cert's public key.
//  Hopefully one will be the key that verifies.

oRsa := CreateObject("Chilkat.Rsa")
oRsa:EncodingMode := "base64url"

oJsonKey := CreateObject("Chilkat.JsonObject")
oPubKey := CreateObject("Chilkat.PublicKey")

nNumKeys := oJson:SizeOfArray("keys")
i := 0
DO WHILE i < nNumKeys
    oJson:I := i

    oJson:ObjectOf2("keys[i]", oJsonKey)

    nSuccess := oPubKey:LoadFromString(oJsonKey:Emit())
    IF (nSuccess == 0)
        ? oPubKey:LastErrorText
        oHttp:destroy()
        oJson:destroy()
        oJsonToken:destroy()
        oSbIdToken:destroy()
        oRsa:destroy()
        oJsonKey:destroy()
        oPubKey:destroy()
        RETURN
    ENDIF

    ? Str(i)
    ? oPubKey:GetPem(1)

    nSuccess := oRsa:UsePublicKey(oPubKey)

    nBVerified := oRsa:VerifyStringENC(cHeaderPlusPayload, "sha256", cSig_b64Url)
    ? "bVerified = " + Str(nBVerified)

    i := i + 1
ENDDO

//  The output is:

//  0
//  -----BEGIN RSA PUBLIC KEY-----
//  MIIBCgKCAQEA4RIrO30287Wsq3gqXCMkUYMVAeI3H8LVE6IXR1krdFeGnZLiGUPw
//  cbkeVpXf3lmJdsStOg+jijces2DZCfPyIBiQuLYfxxmAZE6ErJ0QJFg1stwli2Pz
//  9ncYhFoqi8pXr7kEzEJBTzX4thuw56ydbGsshSEznPXoerCJOc7UI2+n0wFCWQ4Y
//  LHbh/PrWt4vdadyUUUW/QpQHXQLdD8q/Qwqdj0O9zlJE7R6Elw2E9EqnHyIGu1hm
//  LxhqrTru1M18SUhONYbVskV/BCEdVKs//X96849HorWQDCAgVMWfGsdMVq55FAdJ
//  680N5UmQDRynIZ4+PeNGN4S9iw2mbMNEBQIDAQAB
//  -----END RSA PUBLIC KEY-----
//  
//  bVerified = True
//  1
//  -----BEGIN RSA PUBLIC KEY-----
//  MIIBCgKCAQEAxT/ngLZNmT5GBdkLtJZjNeTB+8B5yWgrq/e5eMZ1hrZhcmLK+dSn
//  IkpOPV8/OekV67EnQ7I4II2rcNJnHGrGKZziXO3XN2gtUHE+mBJC99oULSbX/QwB
//  Kz7gC/IBPq9EuxTt6Oq6fPkVQ9DbRIgWJSEGBF/KRaNl3kyAlIZfpY7XgHyJTTv8
//  E7yAcYKPR+36gzdl+ps0sDLKzUuAtZNq8llK0u80z6AtAUIYwWdkEhM9upy6keKI
//  TasIxcsO7M6kZPINUSbh6t5VAm8FuqRmxpgg+9c9/GQSGd89InVypoVzWLQ+wOGg
//  5G4H6JqIgtj0TRFt4gK0eoFi2U0d3l8bcwIDAQAB
//  -----END RSA PUBLIC KEY-----
//  
//  bVerified = False

oHttp:destroy()
oJson:destroy()
oJsonToken:destroy()
oSbIdToken:destroy()
oRsa:destroy()
oJsonKey:destroy()
oPubKey:destroy()