CRYPTO(7) FreeBSD Miscellaneous Information Manual CRYPTO(7)
NAME
crypto - OpenCrypto algorithms
DESCRIPTION
The in-kernel OpenCrypto framework supports several different encryption
and authentication algorithms. This document describes the parameters
and requirements of these algorithms. Unless otherwise noted, all sizes
listed below are in bytes.
Authenticators
Authenticators compute a value (also known as a digest, hash, or tag)
over an input of bytes. In-kernel requests can either compute the value
for a given input, or verify if a given tag matches the computed tag for
a given input. The following authentication algorithms are supported:
Name Nonce Key Sizes Digest Description
CRYPTO_AES_CCM_CBC_MAC 12 16, 24, 32 16 Authentication-
only mode of
AES-CCM
CRYPTO_AES_NIST_GMAC 12 16, 24, 32 16 Galois message
authentication
code
CRYPTO_BLAKE2B 0, 64 64 Blake2b
CRYPTO_BLAKE2S 0, 32 32 Blake2s
CRYPTO_NULL_HMAC 12 IPsec NULL HMAC
CRYPTO_POLY1305 32 16 Poly1305
authenticator
CRYPTO_RIPEMD160 20 RIPE Message
Digest-160
CRYPTO_RIPEMD160_HMAC 64 20 RIPE Message
Digest-160 HMAC
CRYPTO_SHA1 20 SHA-1
CRYPTO_SHA1_HMAC 64 20 SHA-1 HMAC
CRYPTO_SHA2_224 28 SHA-2 224
CRYPTO_SHA2_224_HMAC 64 28 SHA-2 224 HMAC
CRYPTO_SHA2_256 32 SHA-2 256
CRYPTO_SHA2_256_HMAC 64 32 SHA-2 256 HMAC
CRYPTO_SHA2_384 48 SHA-2 384
CRYPTO_SHA2_384_HMAC 128 48 SHA-2 384 HMAC
CRYPTO_SHA2_512 64 SHA-2 512
CRYPTO_SHA2_512_HMAC 128 64 SHA-2 512 HMAC
Block Ciphers
Block ciphers in OCF can only operate on messages whose length is an
exact multiple of the cipher's block size. OCF supports the following
block ciphers:
Name IV Size Block Size Key Sizes Description
CRYPTO_AES_CBC 16 16 16, 24, 32 AES-CBC
CRYPTO_AES_XTS 8 16 32, 64 AES-XTS
CRYPTO_CAMELLIA_CBC 16 16 16, 24, 32 Camellia
CBC
CRYPTO_NULL_CBC 0 4 0-256 IPsec NULL
cipher
CRYPTO_AES_XTS implements XEX Tweakable Block Cipher with Ciphertext
Stealing as defined in NIST SP 800-38E. OCF consumers provide the first
8 bytes of the IV. The remaining 8 bytes are defined to be a block
counter beginning at 0.
NOTE: The ciphertext stealing part is not implemented in all backends
which is why this cipher requires input that is a multiple of the block
size.
Stream Ciphers
Stream ciphers can operate on messages with arbitrary lengths. OCF
supports the following stream ciphers:
Name IV Size Key Sizes Description
CRYPTO_AES_ICM 16 16, 24, 32 AES Counter Mode
CRYPTO_CHACHA20 16 16, 32 ChaCha20
The IV for each request must be provided in crp_iv via the
CRYPTO_F_IV_SEPARATE flag.
CRYPTO_AES_ICM uses the entire IV as a 128-bit big endian block counter.
The IV sets the initial counter value for a message. If a consumer
wishes to use an IV whose value is split into separate nonce and counter
fields (e.g., IPsec), the consumer is responsible for splitting requests
to handle counter rollover.
CRYPTO_CHACHA20 accepts a 16 byte IV. The first 8 bytes are used as a
nonce. The last 8 bytes are used as a 64-bit little-endian block
counter.
Authenticated Encryption with Associated Data Algorithms
AEAD algorithms in OCF combine a stream cipher with an authentication
algorithm to provide both secrecy and authentication. AEAD algorithms
accept additional authentication data (AAD) in addition to the ciphertext
or plaintext. AAD is passed to the authentication algorithm as input in
a method defined by the specific AEAD algorithm.
AEAD algorithms in OCF accept a nonce that is combined with an algorithm-
defined counter to construct the IV for the underlying stream cipher.
This nonce must be provided in crp_iv via the CRYPTO_F_IV_SEPARATE flag.
Some AEAD algorithms support multiple nonce sizes. The first size listed
is the default nonce size.
The following AEAD algorithms are supported:
Name Nonce Key Sizes Tag Description
CRYPTO_AES_NIST_GCM_16 12 16, 24, 32 16 AES
Galois/Counter
Mode
CRYPTO_AES_CCM_16 12, 7-13 16, 24, 32 16 AES Counter
with CBC-MAC
CRYPTO_CHACHA20_POLY1305 12, 8 32 16 ChaCha20-Poly1305
SEE ALSO
crypto(4), crypto(9)
HISTORY
The crypto manual page first appeared in FreeBSD 10.1.
FreeBSD 13.1-RELEASE-p6 October 6, 2021 FreeBSD 13.1-RELEASE-p6
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