Xojo Plugin

Verify JWT Using HS256, HS384, or HS512

See more JSON Web Token (JWT) Examples

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.

Xojo Plugin

Dim success As Boolean
success = False

// 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.

Dim jwt As New Chilkat.Jwt

Dim token As String
token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

// First verify the signature.
// The password used to create this JWT was "secret".
Dim sigVerified As Boolean
sigVerified = jwt.VerifyJwt(token,"secret")
System.DebugLog("with correct password: " + Str(sigVerified))

// Now try with a different password:
sigVerified = jwt.VerifyJwt(token,"secret2")
System.DebugLog("with incorrect password " + Str(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.
Dim leeway As Int32
leeway = 60
Dim bTimeValid As Boolean
bTimeValid = jwt.IsTimeValid(token,leeway)
System.DebugLog("time constraints valid: " + Str(bTimeValid))

// Now let's recover the original claims JSON (the payload).
Dim payload As String
payload = jwt.GetPayload(token)
// The payload will likely be in compact form:
System.DebugLog(payload)

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
Dim json As New Chilkat.JsonObject
success = json.Load(payload)
json.EmitCompact = False
System.DebugLog(json.Emit())

// We can recover the original JOSE header in the same way:
Dim joseHeader As String
joseHeader = jwt.GetHeader(token)
// The payload will likely be in compact form:
System.DebugLog(joseHeader)

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
success = json.Load(joseHeader)
json.EmitCompact = False
System.DebugLog(json.Emit())