blob: e41520f46c89393cc44ae3b96b215be29c38d0e7 [file] [log] [blame]
* Fix a security reduction in CTR_DRBG when the initial seeding obtained a
nonce from entropy. Applications were affected if they called
mbedtls_ctr_drbg_set_nonce_len(), if they called
mbedtls_ctr_drbg_set_entropy_len() with a size that was 3/2 times the key
length, or when the entropy module uses SHA-256 and CTR_DRBG uses AES-256.
In such cases, a random nonce was necessary to achieve the advertised
security strength, but the code incorrectly used a constant instead of
entropy from the nonce.
Found by John Stroebel in #3819 and fixed in #3973.