(Swift 2) Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Creates and validates a JSON Web Signature (JWS) using the private key associated with a certificate on a smart card.

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func chilkatTest() {
    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Load the certificate from a smart card.
    let cert = CkoCert()
    var success: Bool = cert.LoadFromSmartcard("")
    if success == false {
        print("\(cert.LastErrorText)")
        return
    }

    // Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
    // such as selecting a certificate if the card contains multiple certificates with private keys,
    // or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

    // If the associated private key was present on the smartcard, then you can simply
    // get it from the Chilkat cert object:
    var privKey: CkoPrivateKey? = cert.ExportPrivateKey()
    if cert.LastMethodSuccess == false {
        print("\(cert.LastErrorText)")
        return
    }

    // You can check the key type to make sure it's RSA.
    // This will output "rsa" if the key is RSA.
    print("Key type = \(privKey!.KeyType)")

    // Create the JWS Protected Header
    let jwsProtHdr = CkoJsonObject()
    jwsProtHdr.AppendString("alg", value: "RS256")

    let jws = CkoJws()

    // Set the protected header:
    var signatureIndex: Int = 0
    jws.SetProtectedHeader(signatureIndex, json: jwsProtHdr)

    // Set the RSA key:
    jws.SetPrivateKey(signatureIndex, privKey: privKey)

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

    // Create the JWS
    // By default, the compact serialization is used.
    var jwsCompact: String? = jws.CreateJws()
    if jws.LastMethodSuccess != true {
        print("\(jws.LastErrorText)")
        privKey = nil
        return
    }

    print("JWS: \(jwsCompact!)")

    // sample output:
    // JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

    // Now load the JWS, validate, and recover the original text.
    let jws2 = CkoJws()

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

    var rsaPubKey: CkoPublicKey? = privKey!.GetPublicKey()
    privKey = nil

    // Set the RSA public key used for validation.
    signatureIndex = 0
    jws2.SetPublicKey(signatureIndex, pubKey: rsaPubKey)
    rsaPubKey = nil

    // Validate the 1st (and only) signature at index 0..
    var v: Int = jws2.Validate(signatureIndex).intValue
    if v < 0 {
        // Perhaps Chilkat was not unlocked or the trial expired..
        print("Method call failed for some other reason.")
        print("\(jws2.LastErrorText)")
        return
    }

    if v == 0 {
        print("Invalid signature.  The RSA key was incorrect, the JWS was invalid, or both.")
        return
    }

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

    // Recover the original content:
    print("\(jws2.GetPayload("utf-8"))")

    // Examine the protected header:
    var joseHeader: CkoJsonObject? = jws2.GetProtectedHeader(signatureIndex)
    if jws2.LastMethodSuccess != true {
        print("No protected header found at the given index.")
        return
    }

    joseHeader.EmitCompact = false

    print("Protected (JOSE) header:")
    print("\(joseHeader!.Emit())")
    joseHeader = nil

    // Output:

    // 	Signature validated.
    // 	In our village, folks say God crumbles up the old moon into stars.
    // 	Protected (JOSE) header:
    // 	{ 
    // 	  "alg": "RS256"
    // 	}

}