Introduce MD handle type
As has been previously done for ciphersuites, this commit introduces
a zero-cost abstraction layer around the type
mbedtls_md_info const *
whose valid values represent implementations of message digest algorithms.
Access to a particular digest implementation can be requested by name or
digest ID through the API mbedtls_md_info_from_xxx(), which either returns
a valid implementation or NULL, representing failure.
This commit replaces such uses of `mbedtls_md_info const *` by an abstract
type `mbedtls_md_handle_t` whose valid values represent digest implementations,
and which has a designated invalid value MBEDTLS_MD_INVALID_HANDLE.
The purpose of this abstraction layer is to pave the way for builds which
support precisely one digest algorithm. In this case, mbedtls_md_handle_t
can be implemented as a two-valued type, with one value representing the
invalid handle, and the unique valid value representing the unique enabled
digest.
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index f1289cb..ed03854 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -138,7 +138,7 @@
* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED.
*/
int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
- const mbedtls_md_info_t * md_info,
+ mbedtls_md_handle_t md_info,
int (*f_entropy)(void *, unsigned char *, size_t),
void *p_entropy,
const unsigned char *custom,
@@ -158,7 +158,7 @@
* MBEDTLS_ERR_MD_ALLOC_FAILED.
*/
int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
- const mbedtls_md_info_t * md_info,
+ mbedtls_md_handle_t md_info,
const unsigned char *data, size_t data_len );
/**