Ubuntu Manpage: cryptsetup-benchmark - benchmarks ciphers and KDF

Provided by: cryptsetup-bin_2.7.0-1ubuntu4.1_amd64

NAME

       cryptsetup-benchmark - benchmarks ciphers and KDF

SYNOPSIS

       cryptsetup benchmark [<options>]

DESCRIPTION

       Benchmarks ciphers and KDF (key derivation function). Without parameters, it tries to
       measure few common configurations.

       To benchmark other ciphers or modes, you need to specify --cipher and --key-size options.

       To benchmark PBKDF you need to specify --pbkdf or --hash with optional cost parameters
       --iter-time, --pbkdf-memory or --pbkdf-parallel.

       NOTE: This benchmark uses memory only and is only informative. You cannot directly predict
       real storage encryption speed from it.

       For testing block ciphers, this benchmark requires kernel userspace crypto API to be
       available (introduced in Linux kernel 2.6.38). If you are configuring kernel yourself,
       enable "User-space interface for symmetric key cipher algorithms" in "Cryptographic API"
       section (CRYPTO_USER_API_SKCIPHER .config option).

       <options> can be [--cipher, --key-size, --hash, --pbkdf, --iter-time, --pbkdf-memory,
       --pbkdf-parallel].

OPTIONS

--hash, -h <hash-spec>
The specified hash is used for PBKDF2 and AF splitter.

--cipher, -c <cipher-spec>
Set the cipher specification string.

--key-size, -s bits
Sets key size in bits. The argument has to be a multiple of 8. The possible key-sizes
are limited by the cipher and mode used.

See /proc/crypto for more information. Note that key-size in /proc/crypto is stated in
bytes.

This option can be used for open --type plain or luksFormat. All other LUKS actions
will use the key-size specified in the LUKS header. Use cryptsetup --help to show the
compiled-in defaults.

--pbkdf <PBKDF spec>
Set Password-Based Key Derivation Function (PBKDF) algorithm for LUKS keyslot. The
PBKDF can be: pbkdf2 (for PBKDF2 according to RFC2898), argon2i for Argon2i or
argon2id for Argon2id (see Argon2 <https://www.cryptolux.org/index.php/Argon2> for
more info).

For LUKS1, only PBKDF2 is accepted (no need to use this option). The default PBKDF for
LUKS2 is set during compilation time and is available in cryptsetup --help output.

A PBKDF is used for increasing dictionary and brute-force attack cost for keyslot
passwords. The parameters can be time, memory and parallel cost.

For PBKDF2, only time cost (number of iterations) applies. For Argon2i/id, there is
also memory cost (memory required during the process of key derivation) and parallel
cost (number of threads that run in parallel during the key derivation.

Note that increasing memory cost also increases time, so the final parameter values
are measured by a benchmark. The benchmark tries to find iteration time (--iter-time)
with required memory cost --pbkdf-memory. If it is not possible, the memory cost is
decreased as well. The parallel cost --pbkdf-parallel is constant and is checked
against available CPU cores.

You can see all PBKDF parameters for particular LUKS2 keyslot with
cryptsetup-luksDump(8) command.

NOTE: If you do not want to use benchmark and want to specify all parameters directly,
use --pbkdf-force-iterations with --pbkdf-memory and --pbkdf-parallel. This will
override the values without benchmarking. Note it can cause extremely long unlocking
time or cause out-of-memory conditions with unconditional process termination. Use
only in specific cases, for example, if you know that the formatted device will be
used on some small embedded system.

MINIMAL AND MAXIMAL PBKDF COSTS: For PBKDF2, the minimum iteration count is 1000 and
maximum is 4294967295 (maximum for 32bit unsigned integer). Memory and parallel costs
are unused for PBKDF2. For Argon2i and Argon2id, minimum iteration count (CPU cost) is
4 and maximum is 4294967295 (maximum for 32bit unsigned integer). Minimum memory cost
is 32 KiB and maximum is 4 GiB. (Limited by addressable memory on some CPU platforms.)
If the memory cost parameter is benchmarked (not specified by a parameter) it is
always in range from 64 MiB to 1 GiB. The parallel cost minimum is 1 and maximum 4 (if
enough CPUs cores are available, otherwise it is decreased).

--iter-time, -i <number of milliseconds>
The number of milliseconds to spend with PBKDF passphrase processing. Specifying 0 as
parameter selects the compiled-in default.

--pbkdf-memory <number>
Set the memory cost for PBKDF (for Argon2i/id the number represents kilobytes). Note
that it is maximal value, PBKDF benchmark or available physical memory can decrease
it. This option is not available for PBKDF2.

--pbkdf-parallel <number>
Set the parallel cost for PBKDF (number of threads, up to 4). Note that it is maximal
value, it is decreased automatically if CPU online count is lower. This option is not
available for PBKDF2.

--batch-mode, -q
Suppresses all confirmation questions. Use with care!

If the --verify-passphrase option is not specified, this option also switches off the
passphrase verification.

--debug or --debug-json
Run in debug mode with full diagnostic logs. Debug output lines are always prefixed by
#.

If --debug-json is used, additional LUKS2 JSON data structures are printed.

--version, -V
Show the program version.

--usage
Show short option help.

--help, -?
Show help text and default parameters.

REPORTING BUGS

       Report bugs at cryptsetup mailing list <cryptsetup@lists.linux.dev> or in Issues project
       section <https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.

       Please attach output of the failed command with --debug option added.

CRYPTSETUP