Re: [PATCH v12 04/17] crypto: Add aes-helpers file to support some AES modes

[Ilya Leoshkevich <iii@linux.ibm.com>]

On 7/10/26 17:28, Harald Freudenberger wrote:
> Add a new file crypto/aes-helpers.c with simple functions
> to support some AES modes:
> - AES cbc: AES_cbc_encrypt() AES_cbc_decrypt()
> - AES ctr: AES_ctr_encrypt()
> - AES xts: AES_xts_encrypt() AES_xts_decrypt()
> and some AES related helpers:
> - AES_xor()
> - AES_xts_prep_next_tweak()
> Add header file include/crypto/aes-helpers.h for these functions
> 
> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
> Reviewed-by: Finn Callies <fcallies@linux.ibm.com>
> ---
>   crypto/aes-helpers.c         | 106 ++++++++++++++++++++++++++++++++
>   crypto/meson.build           |   1 +
>   include/crypto/aes-helpers.h | 116 +++++++++++++++++++++++++++++++++++
>   3 files changed, 223 insertions(+)
>   create mode 100644 crypto/aes-helpers.c
>   create mode 100644 include/crypto/aes-helpers.h
> 
> diff --git a/crypto/aes-helpers.c b/crypto/aes-helpers.c
> new file mode 100644
> index 0000000000..ff4aa0a385
> --- /dev/null
> +++ b/crypto/aes-helpers.c

[...]

> +void AES_ctr_encrypt(const unsigned char *in, unsigned char *out,
> +                     const unsigned char *ctr, const AES_KEY *key)
> +{
> +    unsigned char buf[AES_BLOCK_SIZE];
> +
> +    /* encrypt ctr => buf */
> +    AES_encrypt(ctr, buf, key);
> +    /* exor input data with encrypted ctr => out */
> +    AES_xor(in, buf, out);
> +}
> +
> +/*
> + * Tweak calculation for AES XTS.
> + * Multiply tweak by α (x) in GF(2^128) per IEEE 1619-2007. The tweak
> + * is a 128-bit little-endian integer (tweak[0]=LSB, tweak[15]=MSB).
> + * This implementation has been verified on litte and big endian.
> + */

Nit: do we need to have this comment twice?
It's already present in the header.

Also typo: litte -> little (but I'm not sure if we even need to state
that in the code).

[...]

Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>