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Get the SSH Server Host Key Fingerprint

Demonstrates the Chilkat Ssh.GetHostKeyFP method, which returns the connected server's host-key fingerprint. The first argument is the hash algorithm (for example SHA256 or MD5), the second controls whether the key type is included, and the third controls whether the hash name is included. The digest is Base64 without trailing padding.

Background: The host-key fingerprint identifies the server. Comparing it against a known-good value is how a client implements host-key pinning — detecting man-in-the-middle attempts or a changed server key. SHA256 is the modern default; MD5 fingerprints are still seen in older tooling but are weaker.

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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 Ssh.GetHostKeyFP method, which returns the server's host-key fingerprint.
    // The 1st argument is the hash algorithm, the 2nd controls whether the key type is included,
    // and the 3rd controls whether the hash name is included.

    const ssh = try chilkat.Ssh.init();
    defer ssh.deinit();

    // Connect to the SSH server.  Port 22 is the usual SSH port.
    const ssh_port = 22;
    ssh.connect("ssh.example.com", ssh_port) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    // Get the SHA256 fingerprint, including the key type and hash name in the result.
    const include_key_type = true;
    const include_hash_name = true;
    const fingerprint = ssh.getHostKeyFP(alloc, "SHA256", include_key_type, include_hash_name) catch {
        std.debug.print("{s}\n", .{try ssh.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Host key fingerprint: {s}\n", .{fingerprint});

    ssh.disconnect();
}