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Key Generation

Generating keys

Key generation can be used in multiple ways:

  1. Generate a key pair and save in new files .pub and .key:

    tessera -keygen
    This command will require interactive input for passwords. If you wish to generate an unlocked key, /dev/null can be used for stdin to tell the application not to expect any input (version 0.8 only):
    # Version 0.8+
    tessera -keygen < /dev/null
    # Version 0.7.x or before
    printf "\n\n" | tessera -keygen

    The -filename option can be used to specify alternate filepaths. Multiple key pairs can be generated at the same time by providing a comma-separated list of values:

    tessera -keygen -filename /path/to/key1,/path/to/key2

  2. Generate a key pair and save to an Azure Key Vault, with DNS name <url>, as secrets with IDs Pub and Key:

    tessera -keygen -keygenvaulttype AZURE -keygenvaulturl <url>

    The -filename option can be used to specify alternate IDs. Multiple key pairs can be generated at the same time by providing a comma-separated list of values:

    tessera -keygen -keygenvaulttype AZURE -keygenvaulturl <url> -filename id1,id2

    Note: If saving new keys with the same ID as keys that already exist in the vault, the existing keys will be replaced by the newer version.

    Environment variables must be set if using an Azure Key Vault, for more information see Setting up an Azure key vault

  3. Generate a key pair and save to a Hashicorp Vault at the secret path secretEngine/secretName with IDs publicKey and privateKey:

    tessera -keygen -keygenvaulttype HASHICORP -keygenvaulturl <url> \
       -keygenvaultsecretengine secretEngine -filename secretName 
    Options exist for configuring TLS and AppRole authentication (by default the AppRole path is set to approle):
    tessera -keygen -keygenvaulttype HASHICORP -keygenvaulturl <url> \
       -keygenvaultsecretengine <secretEngineName> -filename <secretName> \
       -keygenvaultkeystore <JKS file> -keygenvaulttruststore <JKS file> \
       -keygenvaultapprole <authpath>
    The -filename option can be used to generate and store multiple key pairs at the same time:
    tessera -keygen -keygenvaulttype HASHICORP -keygenvaulturl <url> \
       -keygenvaultsecretengine secretEngine -filename myNode/keypairA,myNode/keypairB 
    Saving a new key pair to an existing secret will overwrite the values stored at that secret. Previous versions of secrets may be retained and be retrievable by Tessera depending on how the K/V secrets engine is configured. See Keys for more information on configuring Tessera for use with Vault.

    Environment variables must be set if using a Hashicorp Vault, and a version 2 K/V secret engine must be enabled. For more information see Setting up a Hashicorp Vault.

  4. Generate a key pair, save to files and then start Tessera using a provided config

    tessera -keygen -configfile /path/to/config.json
    tessera -keygen -filename key1 -configfile /path/to/config.json 
    Tessera loads config.json as usual and includes the newly generated key data before starting.

    An updated .json configfile is printed to the terminal (or to a file if using the -output CLI option). No changes are made to the config.json file itself.

Securing private keys

Generated private keys can be encrypted with a password. This is prompted for on the console during key generation. After generating password-protected keys, the password must be added to your configuration to ensure Tessera can read the keys. The password is not saved anywhere but must be added to the configuration else the key will not be able to be decrypted.

Passwords can be added to the json config either inline using "passwords":[], or stored in an external file that is referenced by "passwordFile": "Path". Note that the number of arguments/file-lines provided must equal the total number of private keys. For example, if there are 3 total keys and the second is not password secured, the 2nd argument/line must be blank or contain dummy data.

Tessera uses Argon2 in the process of encrypting private keys. By default, Argon2 is configured as follows:

    "variant": "id",
    "memory": 1048576,
    "iterations": 10,
    "parallelism": 4
The Argon2 configuration can be altered by using the -keygenconfig option. Any override file must have the same format as the default configuration above and all options must be provided.
tessera -keygen -filename /path/to/key1 -keygenconfig /path/to/argonoptions.json

For more information on Argon2 see the Argon2 Github page.

Updating password protected private keys

The password of a private key stored in a file can be updated. Password update uses the --keys.keyData.privateKeyPath CLI option to get the path to the file.

Password update can be used in multiple ways. Running any of these commands will start a CLI prompt to allow you to set a new password.

  1. Add a password to an unlocked key

    tessera -updatepassword --keys.keyData.privateKeyPath /path/to/.key

  2. Change the password of a locked key. This requires providing the current password for the key (either inline or as a file)

    tessera -updatepassword --keys.keyData.privateKeyPath /path/to/.key --keys.passwords <password>
    tessera -updatepassword --keys.keyData.privateKeyPath /path/to/.key --keys.passwordFile /path/to/pwds

  3. Use different Argon2 options from the defaults when updating the password

    tessera --keys.keyData.privateKeyPath <path to keyfile> <algorithm> <iterations> <memory> <parallelism>
    All options have been overriden here but only the options you wish to alter from their defaults need to be provided.