(Go) JWS Using HMAC SHA-256

Creates a JSON Web Signatures (JWS) using HMAC SHA-256.

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    // Note: This example requires Chilkat v9.5.0.66 or greater.

    var success bool

    // First create the JWS Protected Header
    jwsProtHdr := chilkat.NewJsonObject()
    jwsProtHdr.AppendString("typ","JWT")
    jwsProtHdr.AppendString("alg","HS256")
    fmt.Println("JWS Protected Header: ", *jwsProtHdr.Emit())

    // Output:
    // JWS Protected Header: {"typ":"JWT","alg":"HS256"}

    jws := chilkat.NewJws()

    // Set the HMAC key:
    hmacKey := "AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
    signatureIndex := 0
    jws.SetMacKey(signatureIndex,hmacKey,"base64url")

    // Set the protected header:
    jws.SetProtectedHeader(signatureIndex,jwsProtHdr)

    // Set the payload.
    bIncludeBom := false
    payloadStr := "In our village, folks say God crumbles up the old moon into stars."
    jws.SetPayload(payloadStr,"utf-8",bIncludeBom)

    // Create the JWS
    // By default, the compact serialization is used.
    jwsCompact := jws.CreateJws()
    if jws.LastMethodSuccess() != true {
        fmt.Println(jws.LastErrorText())
        jwsProtHdr.DisposeJsonObject()
        jws.DisposeJws()
        return
    }

    fmt.Println("JWS: ", *jwsCompact)

    // sample output:
    // JWS: eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.bsYsi8HJ0N6OqGI1hKQ9QQRNPxxA5qMpcHLtOvXatk8

    // Now load the JWS, validate, and recover the original text.
    jws2 := chilkat.NewJws()

    // Load the JWS.
    success = jws2.LoadJws(*jwsCompact)

    // Set the MAC key used for validation.
    signatureIndex = 0
    jws2.SetMacKey(signatureIndex,hmacKey,"base64url")

    // Validate the 1st (and only) signature at index 0..
    v := jws2.Validate(signatureIndex)
    if v < 0 {
        // Perhaps Chilkat was not unlocked or the trial expired..
        fmt.Println("Method call failed for some other reason.")
        fmt.Println(jws2.LastErrorText())
        jwsProtHdr.DisposeJsonObject()
        jws.DisposeJws()
        jws2.DisposeJws()
        return
    }

    if v == 0 {
        fmt.Println("Invalid signature.  The MAC key was incorrect, the JWS was invalid, or both.")
        jwsProtHdr.DisposeJsonObject()
        jws.DisposeJws()
        jws2.DisposeJws()
        return
    }

    // If we get here, the signature was validated..
    fmt.Println("Signature validated.")

    // Recover the original content:
    fmt.Println(*jws2.GetPayload("utf-8"))

    // Examine the protected header:
    joseHeader := jws2.GetProtectedHeader(signatureIndex)
    if jws2.LastMethodSuccess() != true {
        fmt.Println("No protected header found at the given index.")
        jwsProtHdr.DisposeJsonObject()
        jws.DisposeJws()
        jws2.DisposeJws()
        return
    }

    joseHeader.SetEmitCompact(false)

    fmt.Println("Protected (JOSE) header:")
    fmt.Println(*joseHeader.Emit())
    joseHeader.DisposeJsonObject()

    // Output:

    // 	Signature validated.
    // 	In our village, folks say God crumbles up the old moon into stars.
    // 	Protected (JOSE) header:
    // 	{ 
    // 	  "typ": "JWT",
    // 	  "alg": "HS256"
    // 	} 

    jwsProtHdr.DisposeJsonObject()
    jws.DisposeJws()
    jws2.DisposeJws()