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.Dd April 25, 2021
.Dt SUN8ICRYPTO 4
.Os
.Sh NAME
.Nm sun8icrypto
.Nd driver for Allwinner Crypto Engine
.Sh SYNOPSIS
.Cd "sun8icrypto* at fdt?"
.Sh DESCRIPTION
The
.Nm
driver provides support for the cryptographic processors on Allwinner
A64 and H5 systems-on-a-chip.
The Allwinner Crypto Engine is the successor to the earlier
Allwinner Security System.
.Pp
The hardware includes a True Random Number Generator (TRNG) that is
used as an entropy source for the
.Xr rnd 4
system, and implementations of various cryptographic algorithms
that can be used with
.Xr ipsec 4
and
.Xr crypto 4 .
.Pp
The following
.Xr opencrypto 9
algorithms are supported:
.Pp
.Bl -bullet -compact -offset indent
.It
.Dv CRYPTO_AES_CBC
.It
.Dv CRYPTO_AES_CTR
.It
.Dv CRYPTO_AES_ECB
.It
.Dv CRYPTO_AES_XTS
.It
.Dv CRYPTO_DES_CBC
.It
.Dv CRYPTO_DES_ECB
.It
.Dv CRYPTO_3DES_CBC
.It
.Dv CRYPTO_3DES_ECB
.It
.Dv CRYPTO_MD5
.It
.Dv CRYPTO_SHA1
.It
.Dv CRYPTO_SHA224
.It
.Dv CRYPTO_SHA256
.It
.Dv CRYPTO_SHA1_HMAC
.It
.Dv CRYPTO_SHA2_256_HMAC
.El
.Sh SEE ALSO
.Xr crypto 4 ,
.Xr ipsec 4 ,
.Xr rnd 4 ,
.Xr entropy 7 ,
.Xr opencrypto 9
.Sh HISTORY
The
.Nm
device driver first appeared in
.Nx 9.1 .
.Sh CAVEATS
The
.Nm
TRNG's underlying source of randomness is not documented by Allwinner,
so is not trusted as a reliable source of entropy.
Initial tests using NIST's SP800-90B tools showed highly biased
runs of output, suggesting any potential physical source is not
subject to whitening.
.Pp
Cryptographic operations using
.Nm
are generally slower than using the CPU on supported devices, but provide
an advantage in terms of hardware offloading if the CPU is busy.