Tips to upgrade/migrate OpenSSL lib versions.
[]内は利用可能なversionを示す。
BN_init() [< 1.1.0 removed] -> BN_new() or BN_secure_new()
BN_secure_new() uses secure heap.BN_free() -> BN_clear_free()
BN_clear_free() overwrites the data before BN_free().OPENSSL_secure_clear_free() [>= 1.1.0g]BN_pseudo_rand(), BN_rand() -> BN_priv_rand() [>= 1.1.1] for a secret.BN_pseudo_rand_range(), BN_rand_range() -> BN_priv_rand_range() [>= 1.1.1] for a secret.RAND_pseudo_bytes(), RAND_bytes() -> RAND_priv_bytes() [>= 1.1.1] for a secret.