(Swift 3,4,5...) RSA Sign Binary Data and Verify (Recover the Original Data)

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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

    // Load an RSA private key for signing.
    let privKey = CkoPrivateKey()!
    var success: Bool = privKey.loadEncryptedPemFile("qa_data/pem/rsa_passwd.pem", password: "passwd")
    if success != true {
        print("\(privKey.lastErrorText!)")
        return
    }

    let rsa = CkoRsa()!
    rsa.importPrivateKeyObj(privKey)

    // We have some binary data (in hex) to sign
    var originalData: String? = "0102030405060708090A"
    let bd = CkoBinData()!
    bd.appendEncoded(originalData, encoding: "hex")

    // If successful, the contents of bd are replaced with the RSA signature.
    success = rsa.openSslSignBd(bd)
    if success != true {
        print("\(rsa.lastErrorText!)")
        return
    }

    // Show the RSA signature in base64
    print("\(bd.getEncoded("base64")!)")

    // ------------------------------------------
    // Get the public key from the private key
    var pubKey: CkoPublicKey? = privKey.getPublicKey()

    // Verify the signature and extract the original data.
    let rsa2 = CkoRsa()!
    rsa2.importPublicKeyObj(pubKey)

    var bVerified: Bool = rsa2.openSslVerifyBd(bd)
    print("signature verified: \(bVerified)")

    // Show the original data:
    print("original data: \(bd.getEncoded("hex")!)")

    pubKey = nil

}