(*The function occurring in the VST spec of mbedtls' random function ie no additional input*)
Definition mbedtls_generate s I n :=
match mbedtls_HMAC256_DRBG_generate_function s I n []
with ENTROPY.success (bytes, J) ss =>
match J with ((((VV, KK), RC), _), PR) =>
Some (bytes, ss, HMAC256DRBGabs KK VV RC (hmac256drbgabs_entropy_len I) PR
(hmac256drbgabs_reseed_interval I))
end
| _ => None
end.

Lemma GenUpdate_original_core_length: forall n state l m
(G: GenUpdate_original_core state n = (l,m)),
Datatypes.length l = n%nat.