tree cdcda6cb85958192da759365551e115915866409
parent 64b0623cbbd0b9ee397d5137324376c426b4e8d3
author Hanno Becker <hanno.becker@arm.com> 1567684977 +0100
committer Hanno Becker <hanno.becker@arm.com> 1568018757 +0100

MD: Use no-op for context SHA-256 init() and free()

When MBEDTLS_MD_SINGLE_HASH is set, the underlying digest's
context is embedded into mbedtls_md_context_t, which is
zeroized before the underlying digest's init() function
is called. For those digests where initialization is
zeroization, the init() call can therefore be omitted.

Similarly, when free()-ing an mbedtls_md_context_t, the
entire context is zeroized in the end, hence if the
underlying digest's free() function is zeroization,
it can be omitted.