[U-Boot] [RFC 2/3] lib: rsa: generate additional parameters for public key

[Simon Glass]

Hi AKASHI,

On Fri, 6 Sep 2019 at 00:05, AKASHI Takahiro <takahiro.akashi at linaro.org> wrote:
>
> In the current implementation of FIT_SIGNATURE, five parameters for
> a RSA public key are required while only two of them are essential.
> (See rsa-mod-exp.h and uImage.FIT/signature.txt)
> This is a result of considering relatively limited computer power
> and resources on embedded systems, while such a assumption may not
> be quite practical for other use cases.
>
> In this patch, added is a function, rsa_gen_key_prop(), which will
> generate additional parameters for other uses, in particular
> UEFI secure boot, on the fly.
>
> Note: the current code uses some "big number" routines from BearSSL
> for the calculation.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
>  include/u-boot/rsa-mod-exp.h |   3 +
>  lib/rsa/Makefile             |   2 +-
>  lib/rsa/rsa-keyprop.c        | 631 +++++++++++++++++++++++++++++++++++
>  3 files changed, 635 insertions(+), 1 deletion(-)
>  create mode 100644 lib/rsa/rsa-keyprop.c
>
> diff --git a/include/u-boot/rsa-mod-exp.h b/include/u-boot/rsa-mod-exp.h
> index 8a428c4b6a1a..ca189292d869 100644
> --- a/include/u-boot/rsa-mod-exp.h
> +++ b/include/u-boot/rsa-mod-exp.h
> @@ -26,6 +26,9 @@ struct key_prop {
>         uint32_t exp_len;       /* Exponent length in number of uint8_t */
>  };
>
> +struct key_prop *rsa_gen_key_prop(const void *key, uint32_t keylen);
> +void rsa_free_key_prop(struct key_prop *prop);
> +
>  /**
>   * rsa_mod_exp_sw() - Perform RSA Modular Exponentiation in sw
>   *
> diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile
> index 226d8f3514a9..d66eef74c514 100644
> --- a/lib/rsa/Makefile
> +++ b/lib/rsa/Makefile
> @@ -5,5 +5,5 @@
>  # (C) Copyright 2000-2007
>  # Wolfgang Denk, DENX Software Engineering, wd at denx.de.
>
> -obj-$(CONFIG_RSA_VERIFY) += rsa-verify.o rsa-checksum.o
> +obj-$(CONFIG_RSA_VERIFY) += rsa-verify.o rsa-checksum.o rsa-keyprop.o

Can this code only be included when needed? It seems a bit large,

>  obj-$(CONFIG_RSA_SOFTWARE_EXP) += rsa-mod-exp.o
> diff --git a/lib/rsa/rsa-keyprop.c b/lib/rsa/rsa-keyprop.c
> new file mode 100644
> index 000000000000..e650a931dff9
> --- /dev/null
> +++ b/lib/rsa/rsa-keyprop.c
> @@ -0,0 +1,631 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + *  RSA library - generate parameters for a public key
> + *
> + *  Copyright (c) 2019 Linaro Limited
> + *  Author: AKASHI Takahiro
> + *
> + *  Big number routines in this file come from BearSSL.
> + *  See the original copyright below.
> + *
> + * Copyright (c) 2016 Thomas Pornin <pornin at bolet.org>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining

Can you use SPDX?

> + * a copy of this software and associated documentation files (the
> + * "Software"), to deal in the Software without restriction, including
> + * without limitation the rights to use, copy, modify, merge, publish,
> + * distribute, sublicense, and/or sell copies of the Software, and to
> + * permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be
> + * included in all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
> + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
> + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
> + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
> + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> + * SOFTWARE.
> + */
> +#include <stdio.h>

Should this include common.h?

> +
> +#include <image.h>
> +#include <malloc.h>
> +#include <crypto/internal/rsa.h>

Hmm this seems to be for running on the host?

Regards,
Simon