(Swift 3,4,5...) SSH Tunnel Set Allowed Algorithms

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Demonstrates how to explicitly set the algorithms allowed in the SSH connection protocol for SSH tunneling.

Note: This example requires Chilkat v9.5.0.99 or greater.

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

    var success: Bool
    let ssh_tunnel = CkoSshTunnel()!

    let json = CkoJsonObject()!

    // Here are the algorithms supported by Chilkat at the time this example was written (14-June-2024)

    // ---------------------------
    // SSH Key-Exchange Algorithms
    // ---------------------------
    // curve25519-sha256
    // curve25519-sha256@libssh.org
    // ecdh-sha2-nistp256
    // ecdh-sha2-nistp384
    // ecdh-sha2-nistp521
    // diffie-hellman-group14-sha256
    // diffie-hellman-group16-sha512
    // diffie-hellman-group18-sha512
    // diffie-hellman-group-exchange-sha256
    // diffie-hellman-group1-sha1
    // diffie-hellman-group14-sha1
    // diffie-hellman-group-exchange-sha1

    // ---------------------------
    // SSH Host Key Algorithms
    // ---------------------------
    // ssh-ed25519
    // ecdsa-sha2-nistp256
    // ecdsa-sha2-nistp384
    // ecdsa-sha2-nistp521
    // rsa-sha2-256
    // rsa-sha2-512
    // ssh-rsa
    // ssh-dss

    // ---------------------------
    // SSH Cipher Algorithms
    // ---------------------------
    // chacha20-poly1305@openssh.com
    // aes128-ctr
    // aes256-ctr
    // aes192-ctr
    // aes128-cbc
    // aes256-cbc
    // aes192-cbc
    // aes128-gcm@openssh.com
    // aes256-gcm@openssh.com
    // twofish256-cbc
    // twofish128-cbc
    // blowfish-cbc

    // ---------------------------
    // SSH MAC Algorithms
    // ---------------------------
    // hmac-sha2-256
    // hmac-sha2-512
    // hmac-sha2-256-etm@openssh.com
    // hmac-sha2-512-etm@openssh.com
    // hmac-sha1-etm@openssh.com
    // hmac-sha1
    // hmac-ripemd160
    // hmac-sha1-96
    // hmac-md5

    // Specify the allowed key-exchange, host-key, cipher (i.e. encryption), and mac (i.e. hash) algorithms allowed, in the order of preference.
    // -------------------------------------------------------------------------------------------------------------------------------------------
    // Note: You typically should NOT explicitly set allowed algorithms.
    // By default, Chilkat orders algorithms according to best practices, and pays attention to vulnerabilities such as the "Terrapin Attack".
    // Hard-coding algorthims can make your application brittle and prone to breaking over a long period of time,
    // if a server (at some point in the future) changes its allowed algorithms, or if you connect to a different server,
    // such that the client (Chilkat) and server cannot find a set of mutually agreed-upon algorithms.
    // -------------------------------------------------------------------------------------------------------------------------------------------
    var allowed_kex: String? = "curve25519-sha256@libssh.org,ecdh-sha2-nistp256"
    var allowed_hostKey: String? = "ssh-ed25519,ecdsa-sha2-nistp256"
    var allowed_cipher: String? = "chacha20-poly1305@openssh.com,aes256-ctr"
    var allowed_mac: String? = "hmac-sha2-256,hmac-sha2-512"

    json.update("kex", value: allowed_kex)
    json.update("hostKey", value: allowed_hostKey)
    json.update("cipher", value: allowed_cipher)
    json.update("mac", value: allowed_mac)
    ssh_tunnel.setAllowedAlgorithms(json)

    var port: Int = 22
    success = ssh_tunnel.connect("example.com", port: port)
    if success != true {
        print("\(ssh_tunnel.lastErrorText!)")
        return
    }

    print("Connected.")

    // ....
    // ....

}