tor-gencert [-h|--help] [-v] [-r|--reuse] [--create-identity-key] [-i id_file] [-c cert_file] [-m num] [-a address:port]


tor-gencert generates certificates and private keys for use by Tor directory authorities running the v3 Tor directory protocol, as used by Tor 0.2.0 and later. If you are not running a directory authority, you don’t need to use tor-gencert.

Every directory authority has a long term authority identity key (which is distinct from the identity key it uses as a Tor server); this key should be kept offline in a secure location. It is used to certify shorter-lived signing keys, which are kept online and used by the directory authority to sign votes and consensus documents.

After you use this program to generate a signing key and a certificate, copy those files to the keys subdirectory of your Tor process, and send Tor a SIGHUP signal. DO NOT COPY THE IDENTITY KEY.



Display verbose output.

-h or --help

Display help text and exit.

-r or --reuse

Generate a new certificate, but not a new signing key. This can be used to change the address or lifetime associated with a given key.


Generate a new identity key. You should only use this option the first time you run tor-gencert; in the future, you should use the identity key that’s already there.


Read the identity key from the specified file. If the file is not present and --create-identity-key is provided, create the identity key in the specified file. Default: "./authority_identity_key"


Write the signing key to the specified file. Default: "./authority_signing_key"


Write the certificate to the specified file. Default: "./authority_certificate"

-m NUM

Number of months that the certificate should be valid. Default: 12.

--passphrase-fd FILEDES

Filedescriptor to read the file descriptor from. Ends at the first NUL or newline. Default: read from the terminal.

-a address:port

If provided, advertise the address:port combination as this authority’s preferred directory port in its certificate. If the address is a hostname, the hostname is resolved to an IP before it’s published.


This probably doesn’t run on Windows. That’s not a big issue, since we don’t really want authorities to be running on Windows anyway.



See also the "dir-spec.txt" file, distributed with Tor.


Roger Dingledine <>, Nick Mathewson <>.