(Swift 3,4,5...) Verify JWT Using HS256, HS384, or HS512

Demonstrates how to verify a JWT that was signed using HS256, HS384, or HS512. (HS256 is JWT's acronym for HMAC-SHA256.)

This example verifies the signature. It also does the following:

• Checks to see if the time constraints ("nbf" and "exp") are valid.
• Recovers the original JOSE header.
• Recovers the original claims JSON.

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // Demonstrates how to verify an HMAC JWT using a shared secret (password).

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

    let jwt = CkoJwt()!

    var token: String? = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

    // First verify the signature.
    // The password used to create this JWT was "secret".
    var sigVerified: Bool = jwt.verifyJwt(token, password: "secret")
    print("with correct password: \(sigVerified)")

    // Now try with a different password:
    sigVerified = jwt.verifyJwt(token, password: "secret2")
    print("with incorrect password \(sigVerified)")

    // Let's see if the time constraints, if any, are valid.
    // The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
    // If the current system time is before the "nbf" time, or after the "exp" time,
    // then IsTimeValid will return false/0.
    // Also, we'll allow a leeway of 60 seconds to account for any clock skew.
    // Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
    var leeway: Int = 60
    var bTimeValid: Bool = jwt.isTimeValid(token, leeway: leeway)
    print("time constraints valid: \(bTimeValid)")

    // Now let's recover the original claims JSON (the payload).
    var payload: String? = jwt.getPayload(token)
    // The payload will likely be in compact form:
    print("\(payload!)")

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    let json = CkoJsonObject()!
    var success: Bool = json.load(payload)
    json.emitCompact = false
    print("\(json.emit()!)")

    // We can recover the original JOSE header in the same way:
    var joseHeader: String? = jwt.getHeader(token)
    // The payload will likely be in compact form:
    print("\(joseHeader!)")

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    success = json.load(joseHeader)
    json.emitCompact = false
    print("\(json.emit()!)")

}