(Lianja) 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 Lianja Extension Download Chilkat Lianja Extension

// 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.

loJwt = createobject("CkJwt")

lcToken = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU"

// First verify the signature.
// The password used to create this JWT was "secret".
llSigVerified = loJwt.VerifyJwt(lcToken,"secret")
? "with correct password: " + str(llSigVerified)

// Now try with a different password:
llSigVerified = loJwt.VerifyJwt(lcToken,"secret2")
? "with incorrect password " + str(llSigVerified)

// 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.
lnLeeway = 60
llBTimeValid = loJwt.IsTimeValid(lcToken,lnLeeway)
? "time constraints valid: " + str(llBTimeValid)

// Now let's recover the original claims JSON (the payload).
lcPayload = loJwt.GetPayload(lcToken)
// The payload will likely be in compact form:
? lcPayload

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
loJson = createobject("CkJsonObject")
llSuccess = loJson.Load(lcPayload)
loJson.EmitCompact = .F.
? loJson.Emit()

// We can recover the original JOSE header in the same way:
lcJoseHeader = loJwt.GetHeader(lcToken)
// The payload will likely be in compact form:
? lcJoseHeader

// We can format for human viewing by loading it into Chilkat's JSON object
// and emit.
llSuccess = loJson.Load(lcJoseHeader)
loJson.EmitCompact = .F.
? loJson.Emit()


release loJwt
release loJson