tarsnap-keyregen -- generate a key file for use with tarsnap-recrypt(1)
tarsnap-keyregen --keyfile key-file --oldkey old-key-file --user user-name --machine machine-name [--passphrased] [--passphrase-mem maxmem] [--passphrase-time maxtime] tarsnap-keyregen --version
tarsnap-keyregen generates a set of cryptographic keys which are compati- ble with an existing set of cryptographic keys, registers with the tarsnap server, and writes a key file for use with tarsnap-recrypt(1) and tarsnap(1). The term "compatible" here means that it is possible to re- encrypt archives stored with the first set of keys to be stored with the second set of keys. This is required because Tarsnap has some keys which need to stay the same when re-encrypting data; otherwise, existing ar- chives will become unreadable and cannot be used for deduplication. The --keyfile, --user, --machine, and --oldkey parameters are all required. If the --passphrased option is specified, the user will be prompted to enter a passphrase (twice) to be used to encrypt the key file. If the --passphrase-mem maxmem option is specified, a maximum of maxmem bytes of RAM will be used in the scrypt key derivation function to encrypt the key file; it may be necessary to set this option if a key file is being generated on a system with far more RAM than the system on which the key file will be used. If the --passphrase-time maxtime option is specified, a maximum of approximately maxtime seconds will be used in the scrypt key derivation function to encrypt the key file.