Lua

Get the SFTP Server Host Key Fingerprint

Demonstrates the Chilkat SFtp.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.

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

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Lua

local chilkat = require("chilkat")

-- Demonstrates the SFtp.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.

local sftp = chilkat.SFtp.new()

-- Step 1: Connect the SSH transport.  Port 22 is the usual port.
local port = 22
local success = sftp:connect("sftp.example.com", port)
if not success then
    print(sftp.last_error_text)
    return
end

-- Get the SHA256 fingerprint, including the key type and hash name.
local includeKeyType = true
local includeHashName = true
local fingerprint = sftp:get_host_key_fp("SHA256", includeKeyType, includeHashName)
if not sftp.last_method_success then
    print(sftp.last_error_text)
    return
end

print("Host key fingerprint: " .. fingerprint)

sftp:disconnect()