[PATCH v4 7/8] lib: mbedtls: sha256: add support of key derivation

[Philippe REYNES]

Hi Raymond,


Le 13/12/2024 à 17:58, Raymond Mao a écrit :
>
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>
> Hi Philippe,
>
> On Thu, 12 Dec 2024 at 08:37, Philippe Reynes 
> <philippe.reynes at softathome.com> wrote:
>
>     Adds the support of key derivation using the scheme hkdf.
>     This scheme is defined in rfc5869.
>
>     Signed-off-by: Philippe Reynes <philippe.reynes at softathome.com>
>     ---
>      include/u-boot/sha256.h | 20 ++++++++++++++++++++
>      lib/mbedtls/sha256.c    | 22 ++++++++++++++++++++++
>      2 files changed, 42 insertions(+)
>
>     diff --git a/include/u-boot/sha256.h b/include/u-boot/sha256.h
>     index 2f12275b703..f21173305a6 100644
>     --- a/include/u-boot/sha256.h
>     +++ b/include/u-boot/sha256.h
>     @@ -1,6 +1,8 @@
>      #ifndef _SHA256_H
>      #define _SHA256_H
>
>     +#include <linux/compiler_attributes.h>
>     +#include <linux/errno.h>
>      #include <linux/kconfig.h>
>      #include <linux/types.h>
>
>     @@ -49,4 +51,22 @@ void sha256_hmac(const unsigned char *key, int
>     keylen,
>                      const unsigned char *input, unsigned int ilen,
>                      unsigned char *output);
>
>     +#if CONFIG_IS_ENABLED(HKDF_MBEDTLS)
>     +int sha256_hkdf(const unsigned char *salt, int saltlen,
>     +               const unsigned char *ikm, int ikmlen,
>     +               const unsigned char *info, int infolen,
>     +               unsigned char *output, int outputlen);
>     +#else
>     +static inline int sha256_hkdf(const unsigned char __always_unused
>     *salt,
>     +                             int __always_unused saltlen,
>     +                             const unsigned char __always_unused
>     *ikm,
>     +                             int __always_unused ikmlen,
>     +                             const unsigned char __always_unused
>     *info,
>     +                             int __always_unused infolen,
>     +                             unsigned char __always_unused *output,
>     +                             int __always_unused outputlen) {
>     +       return -EOPNOTSUPP;
>     +}
>     +#endif
>     +
>      #endif /* _SHA256_H */
>     diff --git a/lib/mbedtls/sha256.c b/lib/mbedtls/sha256.c
>     index 2128e598834..b8bc43b612e 100644
>     --- a/lib/mbedtls/sha256.c
>     +++ b/lib/mbedtls/sha256.c
>     @@ -10,6 +10,11 @@
>      #endif /* USE_HOSTCC */
>      #include <u-boot/sha256.h>
>
>     +#if CONFIG_IS_ENABLED(HKDF_MBEDTLS)
>     +#include <mbedtls/md.h>
>     +#include <mbedtls/hkdf.h>
>     +#endif
>     +
>      const u8 sha256_der_prefix[SHA256_DER_LEN] = {
>             0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86,
>             0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05,
>     @@ -33,3 +38,20 @@ void sha256_finish(sha256_context *ctx, uint8_t
>     digest[SHA256_SUM_LEN])
>             mbedtls_sha256_finish(ctx, digest);
>             mbedtls_sha256_free(ctx);
>      }
>     +
>     +#if CONFIG_IS_ENABLED(HKDF_MBEDTLS)
>     +int sha256_hkdf(const unsigned char *salt, int saltlen,
>     +               const unsigned char *ikm, int ikmlen,
>     +               const unsigned char *info, int infolen,
>     +               unsigned char *output, int outputlen)
>     +{
>     +       const mbedtls_md_info_t *md;
>     +
>     +       md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA256);
>
>
> Please check if the return is not NULL.


I have added check in v5


>
>     +
>     +       return mbedtls_hkdf(md, salt, saltlen,
>     +                           ikm, ikmlen,
>     +                           info, infolen,
>     +                           output, outputlen);
>     +}
>     +#endif
>     -- 
>     2.25.1
>
>
> Regards,
> Raymond


Regards,
Philippe