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SFTP Set Allowed Algorithms

See more SFTP Examples

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

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

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    const sftp = try chilkat.SFtp.init();
    defer sftp.deinit();

    const json = try chilkat.JsonObject.init();
    defer json.deinit();

    // 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.
    // -------------------------------------------------------------------------------------------------------------------------------------------
    const allowed_kex = "curve25519-sha256@libssh.org,ecdh-sha2-nistp256";
    const allowed_host_key = "ssh-ed25519,ecdsa-sha2-nistp256";
    const allowed_cipher = "chacha20-poly1305@openssh.com,aes256-ctr";
    const allowed_mac = "hmac-sha2-256,hmac-sha2-512";

    json.updateString("kex", allowed_kex) catch {};
    json.updateString("hostKey", allowed_host_key) catch {};
    json.updateString("cipher", allowed_cipher) catch {};
    json.updateString("mac", allowed_mac) catch {};
    sftp.setAllowedAlgorithms(json) catch {};

    const port = 22;
    sftp.connect("example.com", port) catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Connected.\n", .{});

    // ....
    // ....
}