Kiod
Introduction
kiod is a key manager service daemon for storing private keys and signing digital messages. It provides a secure key storage medium for keys to be encrypted at rest in the associated wallet file. kiod also defines a secure enclave for signing transaction created by clio or a third part library.
Installation
kiod is distributed as part of the Wire software suite. To install kiod just visit the Wire software Installation section.
Usage
| For most users, the easiest way to use kiod is to have clio launch it automatically. Wallet files will be created in the default directory (~/sysio-wallet).
Basic operation
When a wallet is unlocked with the corresponding password, clio can request kiod to sign a transaction with the appropriate private keys.
| kiod is intended to be used by Wire developers only.
Launching kiod manually
kiod can be launched manually from the terminal by running:
kiod
By default, kiod creates the folder ~/sysio-wallet and populates it with a basic config.ini file. The location of the config file can be specified on the command line using the --config-dir argument. The configuration file contains the HTTP server endpoint for incoming HTTP connections and other parameters for cross-origin resource sharing.
| The location of the wallet data folder can be specified on the command line with the --data-dir option.
Auto-locking
By default, kiod is set to lock your wallet after 15 minutes of inactivity. This is configurable in the config.ini by setting the timeout seconds in unlock-timeout. Setting it to 0 will cause kiod to always lock your wallet.
Stopping kiod
The most effective way to stop kiod is to find the kiod process and send a SIGTERM signal to it.
pidof kiod
kill -9 <processId>
Other options
For a list of all commands known to kiod, run:
kiod --help
Application Options:
Config Options for sysio::http_plugin:
--unix-socket-path arg (=kiod.sock) The filename (relative to data-dir) to
create a unix socket for HTTP RPC; set
blank to disable.
--http-server-address arg The local IP and port to listen for
incoming http connections; leave blank
to disable.
--access-control-allow-origin arg Specify the Access-Control-Allow-Origin
to be returned on each request.
--access-control-allow-headers arg Specify the Access-Control-Allow-Header
s to be returned on each request.
--access-control-max-age arg Specify the Access-Control-Max-Age to
be returned on each request.
--access-control-allow-credentials Specify if Access-Control-Allow-Credent
ials: true should be returned on each
request.
--max-body-size arg (=1048576) The maximum body size in bytes allowed
for incoming RPC requests
--http-max-bytes-in-flight-mb arg (=500)
Maximum size in megabytes http_plugin
should use for processing http
requests. 503 error response when
exceeded.
--verbose-http-errors Append the error log to HTTP responses
--http-validate-host arg (=1) If set to false, then any incoming
"Host" header is considered valid
--http-alias arg Additionaly acceptable values for the
"Host" header of incoming HTTP
requests, can be specified multiple
times. Includes http/s_server_address
by default.
--http-threads arg (=2) Number of worker threads in http thread
pool
Config Options for sysio::wallet_plugin:
--wallet-dir arg (=".") The path of the wallet files (absolute
path or relative to application data
dir)
--unlock-timeout arg (=900) Timeout for unlocked wallet in seconds
(default 900 (15 minutes))). Wallets
will automatically lock after specified
number of seconds of inactivity.
Activity is defined as any wallet
command e.g. list-wallets.
Application Config Options:
--plugin arg Plugin(s) to enable, may be specified
multiple times
Application Command Line Options:
-h [ --help ] Print this help message and exit.
-v [ --version ] Print version information.
--print-default-config Print default configuration template
-d [ --data-dir ] arg Directory containing program runtime
data
--config-dir arg Directory containing configuration
files such as config.ini
-c [ --config ] arg (=config.ini) Configuration file name relative to
config-dir
-l [ --logconf ] arg (=logging.json) Logging configuration file name/path
for library users
Key Concepts
Key Storage and Encryption
kiod encrypts key pairs under-the-hood before storing them on a wallet file. Depending on the wallet implementation, say Secure Clave or YubiHSM, a specific cryptographic algorithm will be used. When the standard file system of a UNIX-based OS is used, kiod encrypts key pairs using 256-bit AES in CBC mode.
Wallet Locking Mechanism
From a user's perspective, when a wallet is created, it remains in an unlocked state. Depending on the way kiod is launched, it may remain unlocked until the process is restarted. When a wallet is locked (either by timeout or process restart) the password is required to unlock it.
It must be emphasized that kiod has no authentication/authorization mechanism besides locking/unlocking the wallet for storing/retrieving private keys and signing digital messages.
Service Access and Security
The way kiod is accessed has significant security implications:
-
Domain Socket: When accessed via a domain socket, any UNIX user/group that has the rights to write to the socket file on the filesystem can submit transactions and receive signed transactions from kiod using any key in any unlocked wallet. Security Warning: Proper filesystem permissions are crucial to ensure that only trusted users can access the domain socket.
-
TCP Socket on Localhost: If bound to localhost, any local process (regardless of the owner or permissions) can perform the same actions as mentioned above. This includes potentially risky snippets of JavaScript code running in a web browser.
-
TCP Socket on LAN/WAN: Binding kiod to a LAN/WAN address allows any remote actor who can send packets to the machine running kiod to perform these actions.
That present a huge security risk, even if the communication is encrypted or secured via HTTPS.
Troubleshooting
Common errors
Error: Failed to lock access to wallet directory; is another kiod running"?
Since clio may auto-launch an instance of kiod, it is possible to end up with multiple instances of kiod running. That can cause unexpected behavior or the error message above.
To fix this issue, you can terminate all running kiod instances and restart kiod. The following command will find and terminate all instances of kiod running on the system:
pkill kiod