Isso é basicamente o seu kernel, então " Veja / proc / crypto " é suposto ser "a resposta". A página do manual cryptsetup diz isso:
NOTES ON SUPPORTED CIPHERS, MODES, HASHES AND KEY SIZES
The available combinations of ciphers, modes, hashes and key sizes depend
on kernel support. See /proc/crypto for a list of available options. You
might need to load additional kernel crypto modules in order to get more
options.
For the --hash option, if the crypto backend is libgcrypt, then all algo‐
rithms supported by the gcrypt library are available. For other crypto
backends some algorithms may be missing.
No entanto, meu /proc/crypto
não menciona nenhuma serpente ou xts (aes), então, em vez disso, eu recomendaria ver o que cryptsetup benchmark
reporta (e também mostraria velocidades (ram)). Por exemplo:
$ cryptsetup benchmark
# Tests are approximate using memory only (no storage IO).
PBKDF2-sha1 292752 iterations per second
PBKDF2-sha256 221362 iterations per second
PBKDF2-sha512 142010 iterations per second
PBKDF2-ripemd160 277124 iterations per second
PBKDF2-whirlpool 155727 iterations per second
# Algorithm | Key | Encryption | Decryption
aes-cbc 128b 164.7 MiB/s 164.5 MiB/s
serpent-cbc 128b 119.5 MiB/s 205.0 MiB/s
twofish-cbc 128b 163.5 MiB/s 208.6 MiB/s
aes-cbc 256b 148.4 MiB/s 147.9 MiB/s
serpent-cbc 256b 128.1 MiB/s 205.3 MiB/s
twofish-cbc 256b 202.3 MiB/s 213.1 MiB/s
aes-xts 256b 165.4 MiB/s 145.3 MiB/s
serpent-xts 256b 150.0 MiB/s 194.5 MiB/s
twofish-xts 256b 206.4 MiB/s 206.9 MiB/s
aes-xts 512b 149.4 MiB/s 147.5 MiB/s
serpent-xts 512b 181.7 MiB/s 195.0 MiB/s
twofish-xts 512b 207.1 MiB/s 208.6 MiB/s
Os hashes são as primeiras linhas (sha1, sha256, sha512, ripemd160, whirlpool). As cifras estão no cabeçalho Algoritmo.
Olhando para o que os padrões são, dá uma boa ideia do que é considerado "muito bom" também:
$ cryptsetup --help|tail -n 8
Default compiled-in key and passphrase parameters:
Maximum keyfile size: 8192kB, Maximum interactive passphrase length 512 (characters)
Default PBKDF2 iteration time for LUKS: 1000 (ms)
Default compiled-in device cipher parameters:
loop-AES: aes, Key 256 bits
plain: aes-cbc-essiv:sha256, Key: 256 bits, Password hashing: ripemd160
LUKS1: aes-xts-plain64, Key: 256 bits, LUKS header hashing: sha1, RNG: /dev/urandom
E usar um tamanho de chave maior (com --key-size
) só deve ser mais strong, se for um pouco mais lento.
--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.