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.Dd October 6, 2021
.Dt CRYPTO 7
.Os
.Sh NAME
.Nm crypto
.Nd OpenCrypto algorithms
.Sh 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.
.Ss 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:
.Bl -column "CRYPTO_AES_CCM_CBC_MAC" "XXX" "16, 24, 32" "Digest"
.It Sy Name Ta Sy Nonce Ta Sy Key Sizes Ta Sy Digest Ta Sy Description
.It Dv CRYPTO_AES_CCM_CBC_MAC Ta 12 Ta 16, 24, 32 Ta 16 Ta
Authentication-only mode of AES-CCM
.It Dv CRYPTO_AES_NIST_GMAC Ta 12 Ta 16, 24, 32 Ta 16 Ta
Galois message authentication code
.It Dv CRYPTO_BLAKE2B Ta Ta 0, 64 Ta 64 Ta
Blake2b
.It Dv CRYPTO_BLAKE2S Ta Ta 0, 32 Ta 32 Ta
Blake2s
.It Dv CRYPTO_NULL_HMAC Ta Ta Ta 12 Ta
IPsec NULL HMAC
.It Dv CRYPTO_POLY1305 Ta Ta 32 Ta 16 Ta
Poly1305 authenticator
.It Dv CRYPTO_RIPEMD160 Ta Ta Ta 20 Ta
RIPE Message Digest-160
.It Dv CRYPTO_RIPEMD160_HMAC Ta Ta 64 Ta 20 Ta
RIPE Message Digest-160 HMAC
.It Dv CRYPTO_SHA1 Ta Ta Ta 20 Ta
SHA-1
.It Dv CRYPTO_SHA1_HMAC Ta Ta 64 Ta 20 Ta
SHA-1 HMAC
.It Dv CRYPTO_SHA2_224 Ta Ta Ta 28 Ta
SHA-2 224
.It Dv CRYPTO_SHA2_224_HMAC Ta Ta 64 Ta 28 Ta
SHA-2 224 HMAC
.It Dv CRYPTO_SHA2_256 Ta Ta Ta 32 Ta
SHA-2 256
.It Dv CRYPTO_SHA2_256_HMAC Ta Ta 64 Ta 32 Ta
SHA-2 256 HMAC
.It Dv CRYPTO_SHA2_384 Ta Ta Ta 48 Ta
SHA-2 384
.It Dv CRYPTO_SHA2_384_HMAC Ta Ta 128 Ta 48 Ta
SHA-2 384 HMAC
.It Dv CRYPTO_SHA2_512 Ta Ta Ta 64 Ta
SHA-2 512
.It Dv CRYPTO_SHA2_512_HMAC Ta Ta 128 Ta 64 Ta
SHA-2 512 HMAC
.El
.Ss 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:
.Bl -column "CRYPTO_CAMELLIA_CBC" "IV Size" "Block Size" "16, 24, 32"
.It Sy Name Ta Sy IV Size Ta Sy Block Size Ta Sy Key Sizes Ta Sy Description
.It Dv CRYPTO_AES_CBC Ta 16 Ta 16 Ta 16, 24, 32 Ta
AES-CBC
.It Dv CRYPTO_AES_XTS Ta 8 Ta 16 Ta 32, 64 Ta
AES-XTS
.It Dv CRYPTO_CAMELLIA_CBC Ta 16 Ta 16 Ta 16, 24, 32 Ta
Camellia CBC
.It Dv CRYPTO_NULL_CBC Ta 0 Ta 4 Ta 0-256 Ta
IPsec NULL cipher
.El
.Pp
.Dv 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.
.Pp
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.
.Ss Stream Ciphers
Stream ciphers can operate on messages with arbitrary lengths.
OCF supports the following stream ciphers:
.Bl -column "CRYPTO_CHACHA20" "IV Size" "16, 24, 32"
.It Sy Name Ta Sy IV Size Ta Sy Key Sizes Ta Sy Description
.It Dv CRYPTO_AES_ICM Ta 16 Ta 16, 24, 32 Ta
AES Counter Mode
.It Dv CRYPTO_CHACHA20 Ta 16 Ta 16, 32 Ta
ChaCha20
.El
.Pp
The IV for each request must be provided in
.Fa crp_iv
via the
.Dv CRYPTO_F_IV_SEPARATE
flag.
.Pp
.Dv 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.
.Pp
.Dv 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.
.Ss 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.
.Pp
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
.Fa crp_iv
via the
.Dv CRYPTO_F_IV_SEPARATE
flag.
Some AEAD algorithms support multiple nonce sizes.
The first size listed is the default nonce size.
.Pp
The following AEAD algorithms are supported:
.Bl -column "CRYPTO_AES_NIST_GCM_16" "12, 7-13" "16, 24, 32" "Tag"
.It Sy Name Ta Sy Nonce Ta Sy Key Sizes Ta Sy Tag Ta Sy Description
.It Dv CRYPTO_AES_NIST_GCM_16 Ta 12 Ta 16, 24, 32 Ta 16 Ta
AES Galois/Counter Mode
.It Dv CRYPTO_AES_CCM_16 Ta 12, 7-13 Ta 16, 24, 32 Ta 16 Ta
AES Counter with CBC-MAC
.It Dv CRYPTO_CHACHA20_POLY1305 Ta 12, 8 Ta 32 Ta 16 Ta
ChaCha20-Poly1305
.El
.Sh SEE ALSO
.Xr crypto 4 ,
.Xr crypto 9
.Sh HISTORY
The
.Nm
manual page first appeared in
.Fx 10.1 .