B4X

Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time. B4X

Dim success As Boolean = False

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

'  First, let's get the current date/time from time-c.nist.gov
Dim socket As ChilkatSocket
socket.Initialize("socket")

'  Connect to an NIST time server and read the current date/time
Dim maxWaitMs As Int = 8000
Dim useTls As Boolean = False
success = socket.Connect("time-c.nist.gov", 37, useTls, maxWaitMs)
If success <> True Then
    Log(socket.LastErrorText)
    Return
End If


'  The time server will send a big-endian 32-bit integer representing
'  the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
'  The ReceiveInt32 method will receive a 4-byte integer, but returns
'  True or False to indicate success.  If successful, the integer
'  is obtained via the ReceivedInt property.
Dim bigEndian As Boolean = True
success = socket.ReceiveInt32(bigEndian)
If success <> True Then
    Log(socket.LastErrorText)
    Return
End If


Dim dt As ChilkatDateTime
dt.Initialize
dt.SetFromNtpTime(socket.ReceivedInt)

'  Show the current local date/time
Dim bLocalTime As Boolean = True
Log("Current local date/time: " & dt.GetAsRfc822(bLocalTime))

maxWaitMs = 10
socket.Close(maxWaitMs)

'  ------------------------------------------------------------------------
'  OK, we have the current date/time.  We'll use it to set the IAT property
'  in the code below.

'  First load the JSON key into a string.
Dim fac As ChilkatFileAccess
fac.Initialize
Dim jsonKey As String = fac.ReadEntireTextFile("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", "utf-8")
If fac.LastMethodSuccess <> True Then
    Log(fac.LastErrorText)
    Return
End If


'  A JSON private key should look like this:

'  	{
'  	  "type": "service_account",
'  	  "project_id": "chilkattest-1350",
'  	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
'  	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
'  	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
'  	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
'  	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
'  	  "token_uri": "https://accounts.google.com/o/oauth2/token",
'  	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
'  	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
'  	}

Dim gAuth As ChilkatAuthGoogle
gAuth.Initialize("gAuth")
gAuth.JsonKey = jsonKey

'  Choose a scope.
gAuth.Scope = "https://www.googleapis.com/auth/cloud-platform"

'  Request an access token that is valid for this many seconds.
gAuth.ExpireNumSeconds = 3600

'  If the application is requesting delegated access:
'  The email address of the user for which the application is requesting delegated access,
'  then set the email address here. (Otherwise leave it empty.)
gAuth.SubEmailAddress = ""

'  ------------------------------------------------------------------------
'  Set the IAT using the date/time from the NIST time server.
Dim unixTime As Int = dt.GetAsUnixTime(False)
Log("unixTime = " & unixTime)
gAuth.Iat = unixTime

'  Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
'  The Chilkat socket object is used so that the connection can be established
'  through proxies or an SSH tunnel if desired.
Dim tlsSock As ChilkatSocket
tlsSock.Initialize("tlsSock")
success = tlsSock.Connect("www.googleapis.com", 443, True, 5000)
If success <> True Then
    Log(tlsSock.LastErrorText)
    Return
End If


'  Send the request to obtain the access token.
success = gAuth.ObtainAccessToken(tlsSock)
If success <> True Then
    Log(gAuth.LastErrorText)
    Return
End If


'  Examine the access token:
Log("Access Token: " & gAuth.AccessToken)