tree 3c3df3ce10c877c50b2e2263728fd758e0be17d1
parent e9a3454e0980887a81f7c61dfdd355769296940c
author Gilles Peskine <Gilles.Peskine@arm.com> 1571852376 +0200
committer Gilles Peskine <Gilles.Peskine@arm.com> 1571852825 +0200

CTR_DRBG: define a constant for the default entropy nonce length

The default entropy nonce length is either zero or nonzero depending
on the desired security strength and the entropy length.

The implementation calculates the actual entropy nonce length from the
actual entropy length, and therefore it doesn't need a constant that
indicates the default entropy nonce length. A portable application may
be interested in this constant, however. And our test code could
definitely use it.

Define a constant MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN and use it in
test code. Previously, test_suite_ctr_drbg had knowledge about the
default entropy nonce length built in and test_suite_psa_crypto_init
failed. Now both use MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN.

This change means that the test ctr_drbg_entropy_usage no longer
validates that the default entropy nonce length is sensible. So add a
new test that checks that the default entropy length and the default
entropy nonce length are sufficient to ensure the expected security
strength.