Swift

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. Swift

func chilkatTest() {
    var success: Bool = 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
    let socket = CkoSocket()!

    // Connect to an NIST time server and read the current date/time
    var maxWaitMs: Int = 8000
    var useTls: Bool = false
    success = socket.connect(hostname: "time-c.nist.gov", port: 37, ssl: useTls, maxWaitMs: maxWaitMs)
    if success != true {
        print("\(socket.lastErrorText!)")
        return
    }

    // 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.
    var bigEndian: Bool = true
    success = socket.receiveInt32(bigEndian: bigEndian)
    if success != true {
        print("\(socket.lastErrorText!)")
        return
    }

    let dt = CkoDateTime()!
    dt.set(fromNtpTime: socket.receivedInt.intValue)

    // Show the current local date/time
    var bLocalTime: Bool = true
    print("Current local date/time: \(dt.get(asRfc822: bLocalTime)!)")

    maxWaitMs = 10
    socket.close(maxWaitMs: 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.
    let fac = CkoFileAccess()!
    var jsonKey: String? = fac.readEntireTextFile(path: "qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", charset: "utf-8")
    if fac.lastMethodSuccess != true {
        print("\(fac.lastErrorText!)")
        return
    }

    // 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"
    // 	}

    let gAuth = CkoAuthGoogle()!
    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.
    var unixTime: Int = dt.get(asUnixTime: false)
    print("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.
    let tlsSock = CkoSocket()!
    success = tlsSock.connect(hostname: "www.googleapis.com", port: 443, ssl: true, maxWaitMs: 5000)
    if success != true {
        print("\(tlsSock.lastErrorText!)")
        return
    }

    // Send the request to obtain the access token.
    success = gAuth.obtainAccessToken(connection: tlsSock)
    if success != true {
        print("\(gAuth.lastErrorText!)")
        return
    }

    // Examine the access token:
    print("Access Token: \(gAuth.accessToken!)")

}