(DataFlex) 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 ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoJwt
    String sToken
    Boolean iSigVerified
    Integer iLeeway
    Boolean iBTimeValid
    String sPayload
    Handle hoJson
    Boolean iSuccess
    String sJoseHeader
    String sTemp1

    // 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.

    Get Create (RefClass(cComChilkatJwt)) To hoJwt
    If (Not(IsComObjectCreated(hoJwt))) Begin
        Send CreateComObject of hoJwt
    End

    Move "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vZXhhbXBsZS5vcmciLCJzdWIiOiJKb2huIiwiYXVkIjoiaHR0cDovL2V4YW1wbGUuY29tIiwiaWF0IjoxNDYzNDMxODEyLCJuYmYiOjE0NjM0MzE4MTIsImV4cCI6MTQ2MzQzNTQxMn0.SHnMJ11qJH5pbp22YchT_9fL2HIx0koHiUHLG67_foU" To sToken

    // First verify the signature.
    // The password used to create this JWT was "secret".
    Get ComVerifyJwt Of hoJwt sToken "secret" To iSigVerified
    Showln "with correct password: " iSigVerified

    // Now try with a different password:
    Get ComVerifyJwt Of hoJwt sToken "secret2" To iSigVerified
    Showln "with incorrect password " iSigVerified

    // 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.
    Move 60 To iLeeway
    Get ComIsTimeValid Of hoJwt sToken iLeeway To iBTimeValid
    Showln "time constraints valid: " iBTimeValid

    // Now let's recover the original claims JSON (the payload).
    Get ComGetPayload Of hoJwt sToken To sPayload
    // The payload will likely be in compact form:
    Showln sPayload

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJson
    If (Not(IsComObjectCreated(hoJson))) Begin
        Send CreateComObject of hoJson
    End
    Get ComLoad Of hoJson sPayload To iSuccess
    Set ComEmitCompact Of hoJson To False
    Get ComEmit Of hoJson To sTemp1
    Showln sTemp1

    // We can recover the original JOSE header in the same way:
    Get ComGetHeader Of hoJwt sToken To sJoseHeader
    // The payload will likely be in compact form:
    Showln sJoseHeader

    // We can format for human viewing by loading it into Chilkat's JSON object
    // and emit.
    Get ComLoad Of hoJson sJoseHeader To iSuccess
    Set ComEmitCompact Of hoJson To False
    Get ComEmit Of hoJson To sTemp1
    Showln sTemp1


End_Procedure