[PATCH v2 1/6] dm: crypto: Define UCLASS API for ECDSA signature verification

[Simon Glass]

Hi Alexandru,

On Tue, 16 Mar 2021 at 13:24, Alexandru Gagniuc <mr.nuke.me at gmail.com> wrote:
>
> Define a UCLASS API for verifying ECDSA signatures. Unlike
> UCLASS_MOD_EXP, which focuses strictly on modular exponentiation,
> the ECDSA class focuses on verification. This is done so that it
> better aligns with mach-specific implementations, such as stm32mp.
>
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me at gmail.com>
> ---
>  include/crypto/ecdsa-uclass.h | 39 +++++++++++++++++++++++++++++++++++
>  include/dm/uclass-id.h        |  1 +
>  2 files changed, 40 insertions(+)
>  create mode 100644 include/crypto/ecdsa-uclass.h
>
> diff --git a/include/crypto/ecdsa-uclass.h b/include/crypto/ecdsa-uclass.h
> new file mode 100644
> index 0000000000..189843820a
> --- /dev/null
> +++ b/include/crypto/ecdsa-uclass.h
> @@ -0,0 +1,39 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright (c) 2020, Alexandru Gagniuc <mr.nuke.me at gmail.com>
> + */
> +
> +#include <dm/device.h>
> +
> +/**
> + * struct ecdsa_public_key - ECDSA public key properties
> + *
> + * The struct has pointers to the (x, y) curve coordinates to an ECDSA public
> + * key, as well as the name of the ECDSA curve. The size of the key is inferred
> + * from the 'curve_name'
> + */
> +struct ecdsa_public_key {
> +       const char *curve_name; /* Name of curve, e.g. "prime256v1" */
> +       const void *x;          /* x coordinate of public key */
> +       const void *y;          /* y coordinate of public key */
> +       unsigned int size_bits; /* key size in bits, derived from curve name */
> +};
> +
> +struct ecdsa_ops {
> +       /**
> +        * Verify signature of hash against given public key
> +        *
> +        * @dev:        ECDSA Device
> +        * @pubkey:     ECDSA public key
> +        * @hash:       Hash of binary image
> +        * @hash_len:   Length of hash in bytes
> +        * @signature:  Signature in a raw (R, S) point pair

What is the format of this? I think a better API would be to have a struct here.

> +        * @sig_len:    Length of signature in bytes
> +        *
> +        * This function verifies that the 'signature' of the given 'hash' was
> +        * signed by the private key corresponding to 'pubkey'.
> +        */
> +       int (*verify)(struct udevice *dev, const struct ecdsa_public_key *pubkey,
> +                     const void *hash, size_t hash_len,
> +                     const void *signature, size_t sig_len);
> +};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index d75de368c5..f335f4e5a4 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -47,6 +47,7 @@ enum uclass_id {
>         UCLASS_DSI_HOST,        /* Display Serial Interface host */
>         UCLASS_DMA,             /* Direct Memory Access */
>         UCLASS_DSA,             /* Distributed (Ethernet) Switch Architecture */
> +       UCLASS_ECDSA,           /* Elliptic curve cryptographic device */
>         UCLASS_EFI,             /* EFI managed devices */
>         UCLASS_ETH,             /* Ethernet device */
>         UCLASS_ETH_PHY,         /* Ethernet PHY device */
> --
> 2.26.2
>

Regards,
Simon