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SFTP Authenticate with a Private Key

Demonstrates the Chilkat SFtp.AuthenticatePk method, which authenticates the connected session using public-key authentication. The first argument is the username and the second is an SshKey private key. The matching public key must already be authorized for the account on the server.

Note: The private-key path is relative to the application's current working directory. Supply the path to your own key file.

Background: Public-key authentication is the standard for unattended SFTP transfers: the private key stays on the client, the server trusts the corresponding public key, and no reusable password crosses the wire. The SshKey object imports keys in several formats — this example loads an OpenSSH private key. For an encrypted key, set its Password property before importing.

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

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

    // Demonstrates the SFtp.AuthenticatePk method, which authenticates the connected session using
    // public-key authentication.  The 1st argument is the username and the 2nd is an SshKey private
    // key.  The matching public key must already be authorized for the account on the server.

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

    // Step 1: Connect the SSH transport.  Port 22 is the usual port.
    const port = 22;
    sftp.connect("sftp.example.com", port) catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    };

    // Load the SSH private key.  LoadText reads the file's text, which is then imported.
    const priv_key = try chilkat.SshKey.init();
    defer priv_key.deinit();
    const key_text = priv_key.loadText(alloc, "qa_data/id_rsa") catch {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    };

    priv_key.fromOpenSshPrivateKey(key_text) catch {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    };

    sftp.authenticatePk("mySshLogin", priv_key) catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    };

    // Step 3: Open the SFTP subsystem.  This must be done after authentication and before any
    // file or directory operations.
    sftp.initializeSftp() catch {
        std.debug.print("{s}\n", .{try sftp.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Authenticated with a private key.\n", .{});

    sftp.disconnect();
}