4.13 Managing Key Material Securely
4.13.1 Problem
You
want to minimize the odds of someone getting your raw key material,
particularly if they end up with local access to the machine.
4.13.2 Solution
There are a number of things you can do to reduce these risks:
Securely erase keys as soon as you have finished using them. Use the
spc_memzero( ) function from Recipe 13.2. When you need to store key material, password-protect it, preferably
using a scheme to provide encryption and message integrity so that
you can detect it if the encrypted key file is ever modified. For
example, you can use PBKD2 (see Recipe 4.10) to generate a key from a
password and then use that key to encrypt using a mode that also
provides integrity, such as CWC (see Recipe 5.10). For secret keys in
public key cryptosystems, use PEM-encoding, which affords password
protection (see Recipe 7.17). Store differentiating information with your medium- or long-term
symmetric keys to make sure you don't reuse keys.
(See Recipe 4.11.)
4.13.3 See Also
Recipe 4.10, Recipe 4.11, Recipe 5.10, Recipe 7.17, Recipe 13.2
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